ASHS Certified Horticulturist (CH) Examination — Questions and Answers

Question 1: Which irrigation system delivers water directly to the root zone with the greatest water-use efficiency?

Drip/micro-irrigation (Correct answer)
Flood irrigation
Sprinkler oscillation system
Overhead sprinkler

Correct answer: Drip/micro-irrigation

Drip irrigation applies water slowly at or below the soil surface directly to the root zone, minimizing evaporation and runoff compared to overhead methods.

Question 2: Which fertilizer application method places nutrients directly in the root zone with minimal surface waste?

Deep root injection (Correct answer)
Top dressing
Foliar spray
Broadcasting

Correct answer: Deep root injection

Deep root injection delivers liquid fertilizer directly into the active root zone, bypassing competition from turf and reducing runoff.

Question 3: Hardwood cuttings of deciduous shrubs are typically taken and propagated during which season?

Mid-summer during active growth
Midsummer after bloom
Early spring at bud swell
Late fall to early winter during dormancy (Correct answer)

Correct answer: Late fall to early winter during dormancy

Hardwood cuttings are made from fully lignified, dormant wood in late fall or winter, then stored or stuck in media where they slowly root during winter and spring.

Question 4: Which of the following is classified as a cool-season turfgrass?

Kentucky bluegrass (Correct answer)
St. Augustinegrass
Bermudagrass
Zoysiagrass

Correct answer: Kentucky bluegrass

Kentucky bluegrass is a cool-season grass that grows best at 60–75°F, unlike the warm-season grasses listed.

Question 5: Which practice BEST helps reduce turf compaction in high-traffic areas over time?

Increasing mowing frequency to keep grass short
Combining core aeration with sand topdressing (Correct answer)
Reducing irrigation to limit root growth
Applying a pre-emergent herbicide to prevent weed competition

Correct answer: Combining core aeration with sand topdressing

Core aeration physically removes soil plugs to immediately relieve compaction, and sand topdressing helps maintain open pores and improve long-term soil structure.

Question 6: Which warm-season turfgrass has the highest shade tolerance?

Centipedegrass
Zoysiagrass
St. Augustinegrass (Correct answer)
Bermudagrass

Correct answer: St. Augustinegrass

St. Augustinegrass has the best shade tolerance among commonly used warm-season grasses, making it suitable for partially shaded lawns in the South.

Question 7: Graywater systems for landscape irrigation in the US typically use water from which household sources?

Swimming pool backwash only
Laundry rinse water, bathroom sinks, and showers (Correct answer)
Kitchen sink and dishwasher water
Toilet flushes only

Correct answer: Laundry rinse water, bathroom sinks, and showers

Graywater is lightly used household water from laundry, sinks, and showers (not toilets or kitchen sinks in most US codes) that can be reused for subsurface landscape irrigation.

Question 8: Which type of pruning saw is most appropriate for removing branches 1–3 inches in diameter in tight spaces?

Bow saw
Curved blade folding pruning saw (Correct answer)
Chainsaw
Two-man crosscut saw

Correct answer: Curved blade folding pruning saw

A curved-blade folding pruning saw cuts on the pull stroke, fits into confined canopy spaces, and is sized for branches up to about 3 inches.

Question 9: Which macronutrient is most often responsible for the yellowing of older leaves (chlorosis) in nitrogen-deficient plants?

Calcium
Potassium
Nitrogen (Correct answer)
Phosphorus

Correct answer: Nitrogen

Nitrogen is a mobile nutrient that moves from older leaves to younger growth, causing older leaves to yellow first when deficient.

Question 10: A fertilizer labeled 10-10-10 contains equal percentages of which three primary nutrients?

Potassium, Boron, Manganese
Nitrogen, Calcium, Magnesium
Phosphorus, Sulfur, Iron
Nitrogen, Phosphorus, Potassium (Correct answer)

Correct answer: Nitrogen, Phosphorus, Potassium

The three numbers on a fertilizer label (N-P-K) represent the percentage by weight of nitrogen, phosphorus (as P2O5), and potassium (as K2O).

Question 11: Overseeding dormant warm-season turf with annual or perennial ryegrass in the fall is primarily done to:

Maintain green color during the winter dormancy period (Correct answer)
Reduce irrigation requirements during winter months
Prevent summer annual weed germination the following spring
Permanently replace the warm-season grass with a cool-season species

Correct answer: Maintain green color during the winter dormancy period

Overseeding dormant warm-season turf with ryegrass provides green winter color while the base warm-season grass is dormant.

Question 12: What is the correct location to make a pruning cut when removing a branch from a tree?

Flush with the trunk
Several inches beyond the collar
At the branch union midpoint
Just outside the branch collar (Correct answer)

Correct answer: Just outside the branch collar

Cuts made just outside the branch collar preserve the wound-compartmentalization tissue that the tree uses to seal the wound and prevent decay.

Question 13: For roses, what is the correct pruning angle and direction to promote healthy new cane growth?

Straight horizontal cut, any direction
45-degree angle cut sloping away from an outward-facing bud (Correct answer)
Vertical cut directly above a bud
45-degree angle cut sloping toward a bud

Correct answer: 45-degree angle cut sloping away from an outward-facing bud

A 45-degree angled cut sloping away from an outward-facing bud sheds water away from the bud eye and directs new cane growth outward for an open, vase-shaped habit.

Question 14: What is the primary sign of powdery mildew infection?

Webbing on plant stems and leaves
White, powdery coating on leaves (Correct answer)
Brown or black leaf spots with yellow halos
Water-soaked lesions on leaves

Correct answer: White, powdery coating on leaves

Powdery mildew is a common fungal disease easily identified by its distinctive appearance on plants. The primary sign of infection is a white or grayish powdery coating that forms on the surface of leaves, stems, and sometimes flowers and fruits. This powdery substance is composed of fungal spores and mycelia, making it a clear diagnostic symptom.

Question 15: A plant community approach to landscape design attempts to mimic natural plant associations because:

Plants adapted to growing together need less supplemental water, fertilizer, and pest management (Correct answer)
It maximizes hardscape use
It always uses exotic ornamentals
It eliminates the need for a design plan

Correct answer: Plants adapted to growing together need less supplemental water, fertilizer, and pest management

Designing with plants that naturally co-exist in the same ecological community creates self-sustaining landscapes that require far less irrigation, fertilization, and intervention.

Question 16: Which type of cutting is taken from the actively growing, soft tip of a stem and roots most quickly but wilts most easily?

Hardwood cutting
Semi-hardwood cutting
Softwood cutting (Correct answer)
Leaf-bud cutting

Correct answer: Softwood cutting

Softwood cuttings taken from new, non-lignified stem tips root rapidly because cells are actively dividing, but require high humidity to prevent wilting before roots form.

Question 17: When staking newly planted trees, current best practice recommends:

Using rigid wire to fix the tree immovably
Staking only when necessary and removing stakes within 1 year (Correct answer)
Staking all trees for 2–3 years
Staking below the first main branch

Correct answer: Staking only when necessary and removing stakes within 1 year

Trees should be staked only when they cannot stand alone, using flexible ties, and stakes should be removed within one growing season to allow trunk taper and strength to develop.

Question 18: What is the ideal pH range for most horticultural crops?

5.5–7.0 (Correct answer)
8.0–10.0
3.0–4.5
7.5–9.0

Correct answer: 5.5–7.0

Most horticultural crops thrive in slightly acidic to neutral soil conditions, with an ideal pH range typically falling between 5.5 and 7.0. Within this range, essential plant nutrients are most readily available for uptake by plant roots. Deviations outside this range can lead to nutrient deficiencies or toxicities, hindering plant growth and health.

Question 19: Backflow prevention devices on irrigation systems are required in the US primarily to:

Reduce water hammer in pipes
Filter sediment from emitters
Prevent contaminated irrigation water from entering the potable water supply (Correct answer)
Increase water pressure

Correct answer: Prevent contaminated irrigation water from entering the potable water supply

Backflow preventers protect public drinking water supplies from being contaminated by chemicals, fertilizers, or pathogens that may enter the irrigation system.

Question 20: In planting design, 'accent plants' are used to:

Define the outer boundary of a bed
Form the bulk of ground cover
Create focal points or draw attention to key areas (Correct answer)
Provide the most seasonal color

Correct answer: Create focal points or draw attention to key areas

Accent plants have distinctive form, color, or texture that makes them stand out; they are strategically placed to draw the eye to entrances, focal points, or transitions.

Question 21: Zoysiagrass is best characterized as:

A warm-season grass known for dense, slow-growing, wear-tolerant turf (Correct answer)
A bunch-type grass with no lateral spreading ability
A shade-preferring grass that thrives in northern climates
A cool-season grass with excellent cold hardiness in northern climates

Correct answer: A warm-season grass known for dense, slow-growing, wear-tolerant turf

Zoysiagrass is a warm-season grass prized for its dense, wear-tolerant turf and relatively slow growth rate compared to bermudagrass.

Question 22: A propagation mist system benefits stem cuttings primarily by:

Eliminating the need for rooting hormone
Delivering fertilizer to cuttings
Cooling the rooting medium to 50°F
Maintaining high humidity to reduce transpiration water loss before roots form (Correct answer)

Correct answer: Maintaining high humidity to reduce transpiration water loss before roots form

Intermittent mist keeps cutting foliage wet, reducing stomatal moisture loss and preventing wilting while the cutting is rootless and unable to replace water through uptake.

Question 23: What is 'deadheading' in ornamental horticulture?

Removing basal suckers
Removing spent flowers to promote reblooming (Correct answer)
Removing dead wood from trees
Cutting roots to restrict growth

Correct answer: Removing spent flowers to promote reblooming

Deadheading is the removal of faded or spent flowers to redirect the plant's energy from seed production to continued flowering.

Question 24: The cation exchange capacity (CEC) of a soil influences its ability to:

Control soil temperature
Drain excess water
Support beneficial fungi
Retain and supply positively charged nutrients (Correct answer)

Correct answer: Retain and supply positively charged nutrients

CEC measures how many cations (Ca²⁺, Mg²⁺, K⁺, NH₄⁺) a soil can hold on negatively charged exchange sites, directly affecting nutrient retention.

Question 25: Which of the following is an example of an Integrated Pest Management (IPM) practice?

Eliminating all insects from the environment
Only using organic pesticides
Introducing natural predators to control pests (Correct answer)
Applying chemical pesticides preventively

Correct answer: Introducing natural predators to control pests

Integrated Pest Management (IPM) is a comprehensive approach to pest control that prioritizes long-term prevention and suppression with minimal environmental impact. Introducing natural predators, such as beneficial insects or microorganisms, is a key biological control strategy within IPM. This method targets pests without relying solely on chemical pesticides, aligning with IPM's goal of sustainable pest management.

Question 26: Division as a propagation method is most commonly applied to:

Trees with deep taproots
Tropical woody species
Annual vegetables
Clump-forming perennials and ornamental grasses (Correct answer)

Correct answer: Clump-forming perennials and ornamental grasses

Division splits clump-forming perennials and grasses into multiple rooted sections, rejuvenating crowded plants and quickly producing several new plants identical to the parent.

Question 27: The term 'plant caliper' refers to which tree measurement used in nursery specifications?

Trunk diameter measured at 6 inches above ground (Correct answer)
Root ball diameter
Tree height in feet
Crown spread in feet

Correct answer: Trunk diameter measured at 6 inches above ground

Caliper is the trunk diameter of a nursery tree measured at 6 inches above ground (or 12 inches for trees over 4-inch caliper), used as the standard sizing specification for shade trees.

Question 28: Which planting pattern provides the best canopy coverage for weed suppression in shrub borders?

Single-file border planting
Random scattered placement
Triangular/staggered spacing (offset pattern) (Correct answer)
Row planting in straight lines

Correct answer: Triangular/staggered spacing (offset pattern)

Triangular/staggered spacing offsets plants in adjacent rows, maximizing canopy overlap more efficiently than square or row planting and shading out weeds sooner.

Question 29: Which soil pH range generally maximizes nutrient availability for most landscape plants?

5.5–6.5 (Correct answer)
7.5–8.5
4.0–5.0
8.5–9.5

Correct answer: 5.5–6.5

A pH of 5.5–6.5 keeps most macro- and micronutrients in plant-available forms and is the optimum range for the majority of landscape species.

Question 30: Pleaching is a tree-training technique that results in:

Interwoven branches forming a hedge on stilts or overhead canopy (Correct answer)
Trees grafted onto a single rootstock
Trees pruned into cloud shapes
Compact, low-growing forms through root pruning

Correct answer: Interwoven branches forming a hedge on stilts or overhead canopy

Pleaching weaves or ties together branches of adjacent trees to form a living fence, overhead canopy, or 'hedge on legs' for formal garden structures.

Question 31: Rain sensors on irrigation systems are required by law in some US states because they:

Improve water pressure regulation
Monitor controller battery levels
Detect pipe leaks
Automatically override irrigation during and after sufficient rainfall (Correct answer)

Correct answer: Automatically override irrigation during and after sufficient rainfall

Rain sensors interrupt irrigation cycles during or after adequate rainfall events, preventing wasteful over-irrigation and reducing stormwater runoff, which some states mandate.

Question 32: Which perennial plant is known for its heart-shaped leaves and striking purple flowers?

Bleeding Heart (Dicentra spectabilis)
Columbine (Aquilegia spp.)
Violet (Viola spp.) (Correct answer)
Hosta (Hosta spp.)

Correct answer: Violet (Viola spp.)

Violets (Viola spp.) are well-known perennial plants characterized by their charming heart-shaped leaves and often fragrant, striking purple flowers. They are common in gardens and wild areas, typically blooming in spring. This combination of heart-shaped leaves and purple flowers is a defining characteristic of many violet species.

Question 33: Seasonal color in landscape design refers primarily to:

Permanent hardscape color
Fall foliage only
Paint color of structures
Annual and perennial plants selected for rotating bloom periods (Correct answer)

Correct answer: Annual and perennial plants selected for rotating bloom periods

Seasonal color programs use annuals, bulbs, and perennials strategically rotated or selected to maintain visual interest and bloom through multiple seasons.

Question 34: Stratification of seeds is a pre-germination treatment that involves:

Scarifying the seed coat with acid
Exposing seeds to a period of cold and moist conditions to break dormancy (Correct answer)
Soaking seeds in a gibberellin solution
Drying seeds at high temperature

Correct answer: Exposing seeds to a period of cold and moist conditions to break dormancy

Cold-moist stratification mimics winter conditions, breaking physiological dormancy in many temperate woody plants so they germinate in spring.

Question 35: Scarification of seeds is performed to:

Apply fungicide treatments
Break or weaken the hard seed coat to allow water imbibition (Correct answer)
Improve seed storage life
Provide cold treatment for dormancy breaking

Correct answer: Break or weaken the hard seed coat to allow water imbibition

Scarification physically or chemically abrades the impermeable seed coat of hard-seeded species, allowing water and oxygen to enter and initiation of germination.

Question 36: Which component of potting media provides aeration and prevents compaction?

Coir
Vermiculite
Peat moss
Sand (Correct answer)

Correct answer: Sand

In potting media, sand is primarily used to provide aeration and improve drainage, which helps prevent compaction. Its relatively large, coarse particles create spaces between them, allowing air to circulate around plant roots and water to drain efficiently. While other components like peat moss retain water, sand's role is crucial for structural integrity and gas exchange.

Question 37: Tensiometers measure soil moisture by indicating:

Tension (suction force) with which the soil holds water (Correct answer)
Volume of water stored in the soil
Depth of the water table
Ion concentration in soil water

Correct answer: Tension (suction force) with which the soil holds water

Tensiometers measure matric potential — the suction force with which soil particles hold water — which indicates how hard plant roots must work to extract moisture.

Question 38: The Landscape Architect Licensure Examination (LARE) is required for professional licensure as a landscape architect, while CH certification is administered by which organization?

American Nursery and Landscape Association (ANLA)
American Society for Horticultural Science (ASHS)
American Society of Landscape Architects (ASLA)
American Horticulture Industry Association (AHIA) / PLANET (Correct answer)

Correct answer: American Horticulture Industry Association (AHIA) / PLANET

The Certified Horticulturist (CH) credential is administered by the National Association of Landscape Professionals (NALP), formerly known as PLANET/AHIA.

Question 39: Which factor most directly affects irrigation precipitation rate (how fast water is applied)?

Pipe material
Nozzle flow rate and spacing (Correct answer)
Soil organic matter content
Controller brand

Correct answer: Nozzle flow rate and spacing

Precipitation rate (inches per hour) is calculated from nozzle flow rate and spacing; mismatched nozzles on the same zone create highly uneven application.

Question 40: The 'Right Plant, Right Place' principle in landscape design primarily considers:

Matching plant cultural requirements to existing site conditions (Correct answer)
Seasonal color sequencing
Plant cost and availability only
Container size at installation

Correct answer: Matching plant cultural requirements to existing site conditions

Right Plant, Right Place matches each plant's light, moisture, soil, climate zone, and space needs to existing site conditions, reducing maintenance and plant failure.

Question 41: Which plant is characterized by its needle-like leaves and is commonly used in drought-tolerant landscaping?

Blue Spruce (Picea pungens)
Lavender (Lavandula spp.)
Juniper (Juniperus spp.) (Correct answer)
Rosemary (Salvia rosmarinus)

Correct answer: Juniper (Juniperus spp.)

Juniper (Juniperus spp.) is a genus of coniferous plants widely recognized for its distinctive needle-like or scale-like leaves. Many juniper species are highly drought-tolerant once established, making them excellent choices for xeriscaping and low-water landscapes. They are also valued for their evergreen foliage and diverse forms, from groundcovers to upright trees.

Question 42: Magnesium is considered a secondary macronutrient and is an essential component of which plant molecule?

Chlorophyll (Correct answer)
Pectin
Lignin
Cellulose

Correct answer: Chlorophyll

Magnesium is the central atom in the chlorophyll molecule, making it critical for photosynthesis and green coloration.

Question 43: What mowing height is generally recommended for Kentucky bluegrass during summer stress periods?

2.5–3.5 inches (Correct answer)
0.5–1 inch
4–5 inches
1–1.5 inches

Correct answer: 2.5–3.5 inches

Kentucky bluegrass is typically maintained at 2.5–3.5 inches in summer to promote deeper roots and improve heat and drought stress tolerance.

Question 44: Which of the following is a fast-growing tree with compound leaves and invasive potential in many regions?

Tree of Heaven (Ailanthus altissima)
Sugar Maple (Acer saccharum)
Northern Red Oak (Quercus rubra)
Tree of Heaven (Ailanthus altissima) (Correct answer)

Correct answer: Tree of Heaven (Ailanthus altissima)

The Tree of Heaven (Ailanthus altissima) is an extremely fast-growing deciduous tree with large, pinnately compound leaves. It is notorious for its invasive potential in many regions, rapidly colonizing disturbed areas and outcompeting native vegetation. Its aggressive growth and prolific seed production make it a significant ecological threat.

Question 45: A landscape design element that provides a transition between tall trees and low ground covers is called a:

Canopy element
Screen planting
Terminus
Understory layer or shrub layer (Correct answer)

Correct answer: Understory layer or shrub layer

The understory or shrub layer bridges the visual and physical gap between tall overstory trees and low ground-level plantings, creating layered depth in a planting design.

Question 46: Hydraulic zoning in irrigation design groups plants together based on:

Root depth only
Plant color and texture
Bloom season
Similar water requirements (hydrozones) (Correct answer)

Correct answer: Similar water requirements (hydrozones)

Hydrozoning groups plants with similar water needs on the same irrigation zone so water can be applied efficiently without over- or under-irrigating any plant.

Question 47: Dollar spot disease in turfgrass is most commonly associated with which conditions?

High soil pH and extended drought stress
Compacted soils and heavy shade throughout the day
High nitrogen fertility and consistently wet soils
Low nitrogen fertility and alternating wet/dry periods with moderate temperatures (Correct answer)

Correct answer: Low nitrogen fertility and alternating wet/dry periods with moderate temperatures

Dollar spot is favored by low nitrogen levels and periods of alternating moisture such as heavy dew or light, frequent irrigation, and can be partly managed with adequate nitrogen fertility.

Question 48: Bottom heat in propagation systems (typically 70–75°F media temperature) is used because:

Warm root zone temperatures accelerate callus formation and root initiation in cuttings (Correct answer)
It mimics cold stratification conditions
It hardens off plants before transplanting
It sterilizes the propagation medium

Correct answer: Warm root zone temperatures accelerate callus formation and root initiation in cuttings

Enzymatic and cell division processes that produce roots are temperature-dependent; warm media (70–75°F) speeds rooting while cooler air temperatures reduce transpiration stress.

Question 49: Iron deficiency interveinal chlorosis on young leaves is most commonly caused by which soil condition?

Low soil temperature
Excessive nitrogen
High soil pH (Correct answer)
Low soil pH

Correct answer: High soil pH

High soil pH (alkaline conditions) causes iron to precipitate into unavailable forms, resulting in interveinal chlorosis on new leaves.

Question 50: Phosphorus in fertilizers is expressed as which chemical compound equivalent on the label?

P
H3PO4
P2O5 (Correct answer)
PO4

Correct answer: P2O5

Federal law requires that phosphorus content on fertilizer labels be expressed as the oxide equivalent P2O5, even though modern soils labs report elemental P.

Question 51: Which practice is most effective in minimizing soil erosion on a sloped area?

Adding inorganic fertilizers
Planting ground covers or grasses (Correct answer)
Frequent watering
Removing vegetation

Correct answer: Planting ground covers or grasses

Planting ground covers or grasses is highly effective in minimizing soil erosion on sloped areas. The dense network of roots from these plants binds soil particles together, preventing them from being washed away by rain or blown by wind. Additionally, the foliage helps to intercept rainfall, reducing its impact force on the soil surface and promoting water infiltration.

Question 52: Thatch in a turfgrass stand is best described as:

A fungal disease affecting turfgrass crowns
Dead grass clippings left on the lawn surface
A type of soil amendment used during turf renovation
A layer of living and dead organic matter between the soil surface and green grass (Correct answer)

Correct answer: A layer of living and dead organic matter between the soil surface and green grass

Thatch is the layer of accumulated living and dead organic matter (stems, roots, rhizomes) situated between the soil surface and the actively growing green grass.

Question 53: What is topdressing in turfgrass management?

Adding granular fertilizer on top of a straw mulch layer
Spreading a thin, uniform layer of material such as sand or compost over the turf surface (Correct answer)
Applying a post-emergent herbicide to the surface of the turf
Mowing at a higher height to cover thin or bare spots

Correct answer: Spreading a thin, uniform layer of material such as sand or compost over the turf surface

Topdressing involves spreading a thin, uniform layer of material (sand, compost, or soil mix) to improve surface smoothness, thatch decomposition, and soil physical properties.

Question 54: Coppicing is a historic pruning practice that involves:

Training a single stem to a vertical form
Grafting new growth onto old rootstock
Removing the top third of the canopy each year
Cutting stems to near ground level on a regular cycle to produce multiple young shoots (Correct answer)

Correct answer: Cutting stems to near ground level on a regular cycle to produce multiple young shoots

Coppicing cuts woody shrubs or trees nearly to the ground to stimulate vigorous juvenile regrowth, historically used for producing poles, firewood, and ornamental colored stems.

Question 55: Which condition is an early visible sign of plant water stress (drought stress)?

Leaf yellowing starting from the base
Purple stem coloration
Leaf curl or wilting in the morning (Correct answer)
Sudden drop of fruit

Correct answer: Leaf curl or wilting in the morning

Temporary wilting or leaf rolling/curling during morning hours (before midday heat) indicates significant water deficit and is an early stress indicator in many species.

Question 56: Crossing or rubbing branches should be removed during pruning because they:

Block air movement uniformly
Consume too many nutrients
Compete for sunlight only
Create wounds that invite pathogens and structural weaknesses (Correct answer)

Correct answer: Create wounds that invite pathogens and structural weaknesses

Branches that cross and rub create abrasion wounds that strip bark, exposing the tree to fungal and bacterial pathogens while also creating structural weak points.

Question 57: The primary advantage of vegetative (clonal) propagation over seed propagation for cultivars is:

Offspring are genetically identical to the parent, preserving cultivar traits (Correct answer)
It produces more genetic variation for selection
It is always cheaper per plant
Seeds germinate faster than cuttings root

Correct answer: Offspring are genetically identical to the parent, preserving cultivar traits

Vegetative propagation produces clones, ensuring that named cultivars with specific form, flower color, or disease resistance maintain those traits exactly, which is impossible through cross-pollinated seed.

Question 58: The best time to prune spring-flowering shrubs such as lilac (Syringa spp.) in the US is:

Immediately after flowering (Correct answer)
Mid-summer
Late winter before bloom
Late fall

Correct answer: Immediately after flowering

Spring-flowering shrubs set their flower buds on old wood during summer; pruning right after bloom preserves next year's buds while still shaping the plant.

Question 59: What is cation exchange capacity (CEC) in soil?

The soil’s ability to support root growth
The soil’s organic matter content
The soil’s ability to retain and release water
The soil’s ability to hold and exchange nutrients (Correct answer)

Correct answer: The soil’s ability to hold and exchange nutrients

Cation exchange capacity (CEC) is a fundamental soil property that measures the soil's ability to hold onto positively charged nutrient ions (cations) and then release them to plant roots. Soils with a high CEC, typically those rich in clay and organic matter, are more fertile because they can store and supply more essential nutrients like calcium, magnesium, and potassium to plants.

Question 60: When installing balled-and-burlapped (B&B) trees, the top of the root ball should be placed:

12 inches above grade on a mound
At or slightly above the surrounding grade (Correct answer)
6 inches below grade
Exactly at grade

Correct answer: At or slightly above the surrounding grade

Setting B&B trees at or 1–2 inches above grade accommodates soil settlement and prevents the root flare from being buried, which can cause girdling and decline.

Question 61: Fertilizer burn on plant roots is primarily caused by high concentrations of which factor?

Carbon dioxide
Soluble salts (Correct answer)
Organic matter
Water

Correct answer: Soluble salts

Excessive soluble salts from over-fertilization create a high-osmotic-potential environment that draws water out of root cells, causing burn.

Question 62: What type of pest is controlled using Bacillus thuringiensis (Bt)?

Fungal pathogens
Nematodes
Caterpillars and larvae (Correct answer)
Aphids

Correct answer: Caterpillars and larvae

Bacillus thuringiensis (Bt) is a naturally occurring bacterium widely used as a biological pesticide. It produces protein crystals that are toxic specifically to the larvae of certain insect orders, most notably caterpillars (Lepidoptera) and some beetle larvae, when ingested. Bt is valued for its selective action, as it generally does not harm beneficial insects, humans, or other animals.

Question 63: What is the common name for Quercus alba?

White Oak (Correct answer)
Red Oak
Live Oak
Black Oak

Correct answer: White Oak

Quercus alba is the scientific name for the White Oak, a prominent and long-lived deciduous tree native to eastern and central North America. It is distinguished by its light gray, scaly bark and leaves with rounded lobes, which turn reddish-brown in the fall. The name "White Oak" refers to its pale bark and light-colored wood.

Question 64: In seed propagation, the term 'germination percentage' refers to:

The proportion of seeds in a lot that successfully germinate under optimal conditions (Correct answer)
Moisture content of stored seed
The percent of seeds that produce male flowers
Percentage of seeds treated with fungicide

Correct answer: The proportion of seeds in a lot that successfully germinate under optimal conditions

Germination percentage indicates seed lot viability and is used to calculate seeding rates; a lower percentage means more seeds must be sown to achieve the desired plant stand.

Question 65: What does ADA compliance mean for commercial landscape installations in the US?

Providing adequate wildlife habitat
Meeting specific plant diversity requirements
Ensuring paths and facilities are accessible to people with disabilities (Correct answer)
Using only native plant species

Correct answer: Ensuring paths and facilities are accessible to people with disabilities

The Americans with Disabilities Act (ADA) requires landscape paths, ramps, and facilities on commercial and public properties to meet accessibility standards for wheelchair users and others with disabilities.

Question 66: What is the primary goal of xeriscaping?

Attracting pollinators
Reducing water usage in landscapes (Correct answer)
Increasing biodiversity
Preventing soil erosion

Correct answer: Reducing water usage in landscapes

Xeriscaping is a landscaping approach specifically designed to conserve water, particularly in arid or drought-prone regions. Its primary goal is to create beautiful and functional landscapes that require minimal supplemental irrigation. This is achieved through practices like selecting drought-tolerant plants, using efficient irrigation systems, and incorporating mulches to retain soil moisture.

Question 67: Brown patch disease in turfgrass is caused by which pathogen?

Sclerotinia homoeocarpa
Pythium aphanidermatum
Fusarium graminearum
Rhizoctonia solani (Correct answer)

Correct answer: Rhizoctonia solani

Brown patch is caused by the fungal pathogen Rhizoctonia solani and is favored by hot, humid conditions with high nighttime temperatures and excessive nitrogen.

Question 68: Soil compaction during landscape installation is best prevented by:

Watering soil heavily before equipment use
Rototilling compacted areas after installation
Adding sand to clay soils
Restricting heavy equipment to designated access routes and protecting root zones (Correct answer)

Correct answer: Restricting heavy equipment to designated access routes and protecting root zones

Limiting equipment access to designated lanes and placing matting over root zones prevents compaction of soil pores, preserving aeration and drainage around plants.

Question 69: Which soil texture has the highest water retention capacity?

Loam
Sand
Clay (Correct answer)
Silt

Correct answer: Clay

Clay soil particles are the smallest of the three main soil textures (sand, silt, clay), giving clay soil a very fine texture and tightly packed structure. This small particle size and large surface area allow clay to hold a significant amount of water, giving it the highest water retention capacity among the soil types. While beneficial for water storage, excessive clay can lead to poor drainage and aeration.

Question 70: Irrigation run times should generally be split into shorter 'cycle and soak' cycles for slopes and clay soils to:

Reduce pump wear
Prevent head pop-up failures
Increase water penetration speed
Allow water to infiltrate before runoff occurs (Correct answer)

Correct answer: Allow water to infiltrate before runoff occurs

Cycle-and-soak scheduling runs short irrigation cycles with rest intervals, allowing slow-draining soils or slopes time to absorb water between applications and eliminating runoff.

Question 71: What is the primary benefit of using slow-release nitrogen fertilizers on turfgrass compared to quick-release forms?

They significantly reduce soil pH more effectively than quick-release products
They provide a more consistent nutrient supply over time and reduce the risk of fertilizer burn (Correct answer)
They release nitrogen faster than soluble quick-release fertilizers
They eliminate the need for phosphorus and potassium supplementation

Correct answer: They provide a more consistent nutrient supply over time and reduce the risk of fertilizer burn

Slow-release nitrogen fertilizers release nutrients gradually over weeks or months, providing sustained turf nutrition while minimizing salt burn, leaching, and surge growth.

Question 72: In a propagation context, 'juvenility' in plant tissue refers to:

Rootstock tissue below the graft union
Seeds that have not yet stratified
Tissue from young seedlings only
A physiological state of plant tissue associated with easier rooting and greater plasticity (Correct answer)

Correct answer: A physiological state of plant tissue associated with easier rooting and greater plasticity

Juvenile plant tissue is physiologically younger, often characterized by easier adventitious rooting, different leaf shapes, and greater growth plasticity, making it preferred for cuttings.

Question 73: Soil EC (electrical conductivity) is used in horticulture primarily to measure:

Soil texture
Microbial activity
Total dissolved salts (Correct answer)
Organic matter content

Correct answer: Total dissolved salts

EC meters measure the ability of a solution to conduct electricity, which directly correlates with total dissolved salt concentration in the soil or growing medium.

Question 74: In landscape design, 'negative space' refers to:

Shaded areas beneath dense canopies
Open, unplanted areas that provide visual rest and define planted forms (Correct answer)
Areas with dead plants
Areas with poor soil

Correct answer: Open, unplanted areas that provide visual rest and define planted forms

Negative space — lawn panels, open water, paving — provides visual breathing room that frames and highlights planted areas, a key principle in balanced composition.

Question 75: Pre-emergent herbicides for crabgrass control are most effective when applied:

After crabgrass has fully germinated and plants are actively growing
In fall after the first killing frost to prevent spring germination
When soil temperatures consistently reach 55–60°F at a 4-inch depth in spring (Correct answer)
Before soil temperatures reach 55°F at a 4-inch depth in spring

Correct answer: When soil temperatures consistently reach 55–60°F at a 4-inch depth in spring

Pre-emergent herbicides must be in place before crabgrass seeds germinate, which occurs when soil temperatures at a 4-inch depth reach 55–60°F in spring.

Question 76: Foliar fertilization is most effective for correcting deficiencies of which type of nutrients?

Macronutrients applied at high rates
Mobile nutrients like nitrogen
Immobile micronutrients such as iron and manganese (Correct answer)
Calcium and sulfur

Correct answer: Immobile micronutrients such as iron and manganese

Foliar sprays are particularly effective for immobile micronutrients like iron, manganese, and zinc because they bypass soil chemistry issues that limit uptake.

Question 77: What is the purpose of a buffer zone in environmental stewardship?

To separate agricultural fields from natural water bodies (Correct answer)
To create a windbreak for crops
To enhance pesticide effectiveness
To increase irrigation efficiency

Correct answer: To separate agricultural fields from natural water bodies

A buffer zone in environmental stewardship is typically a strip of vegetation established between agricultural fields and natural water bodies. Its primary purpose is to act as a filter, intercepting and absorbing runoff containing sediments, excess nutrients, and pesticides. This helps prevent these pollutants from entering rivers, lakes, and streams, thereby protecting water quality and aquatic ecosystems.

Question 78: Wound dressings and tree paints applied after pruning cuts are:

Generally not recommended as they can trap moisture and pathogens (Correct answer)
Required for cuts larger than 2 inches
Beneficial for conifers only
Strongly recommended for all cuts

Correct answer: Generally not recommended as they can trap moisture and pathogens

Research has shown wound dressings do not accelerate wound closure and can seal in moisture and pathogens, potentially increasing decay compared to leaving cuts to seal naturally.

Question 79: Evapotranspiration (ET) represents the combined water loss from:

Soil evaporation and plant transpiration (Correct answer)
Rainfall and irrigation
Root uptake and guttation
Deep percolation and runoff

Correct answer: Soil evaporation and plant transpiration

ET combines evaporation from soil surfaces and transpiration from plant leaves, and is used to calculate irrigation replacement needs.

Question 80: Disbudding in chrysanthemum production is done primarily to:

Produce one large terminal flower per stem (Correct answer)
Prevent disease spread
Increase the number of small flowers
Remove diseased tissue

Correct answer: Produce one large terminal flower per stem

Disbudding removes lateral flower buds so that all energy is directed to the single terminal bud, yielding a larger, exhibition-quality bloom.

Question 81: Which pest is most commonly associated with honeydew production on plants?

Aphids (Correct answer)
Caterpillars
Japanese beetles
Spider mites

Correct answer: Aphids

Aphids are small, sap-sucking insects that feed on plant juices, often found in clusters on new growth or the undersides of leaves. As they feed, they excrete a sticky, sugary waste product called honeydew. This honeydew can then lead to the growth of sooty mold, which is a common secondary sign of an aphid infestation.

Question 82: Tissue culture (micropropagation) is preferred for propagating some plant species because it:

Is less expensive than cuttings
Only works with seed propagation
Requires no sterile conditions
Produces large numbers of genetically uniform, disease-free plants rapidly (Correct answer)

Correct answer: Produces large numbers of genetically uniform, disease-free plants rapidly

Tissue culture propagates thousands of identical, pathogen-free plantlets from tiny explants in sterile conditions, enabling rapid large-scale production of superior clones.

Question 83: Which micronutrient deficiency causes 'little leaf' or 'rosette' symptoms in fruit trees and ornamentals?

Copper
Manganese
Boron
Zinc (Correct answer)

Correct answer: Zinc

Zinc deficiency causes shortened internodes and clustered small leaves ('little leaf' or 'rosette') because zinc is required for auxin synthesis.

Question 84: Renewal pruning of overgrown deciduous shrubs typically involves removing approximately how much of the oldest canes each year over several years?

All canes at once
Exactly half each year
One-third of the oldest canes annually (Correct answer)
Only tip growth each season

Correct answer: One-third of the oldest canes annually

The one-third renewal method gradually replaces old, unproductive canes with vigorous new growth over three years without shocking the plant.

Question 85: In landscape design, the principle of 'unity' is achieved by:

Repeating compatible elements to create a cohesive, harmonious composition (Correct answer)
Maximizing color contrast throughout the landscape
Using as many different plant species as possible
Mixing all design styles in one space

Correct answer: Repeating compatible elements to create a cohesive, harmonious composition

Unity is created through repetition of plants, colors, textures, or forms that ties the design together into a visually coherent whole.

Question 86: Over-irrigation of landscape plants most commonly leads to which root problem?

Excessive root hair growth
Salt burn
Nutrient toxicity
Anaerobic conditions promoting root rot pathogens (Correct answer)

Correct answer: Anaerobic conditions promoting root rot pathogens

Waterlogged soils become oxygen-depleted (anaerobic), promoting Phytophthora, Pythium, and other water mold pathogens that cause root rot.

Question 87: Which turfgrass spreads primarily by stolons (above-ground runners)?

Bermudagrass (Correct answer)
Tall fescue
Perennial ryegrass
Kentucky bluegrass

Correct answer: Bermudagrass

Bermudagrass spreads aggressively by both stolons (above-ground) and rhizomes (below-ground), contributing to its rapid lateral spreading habit.

Question 88: Mulching around plants reduces irrigation needs primarily by:

Adding nutrients to the soil
Increasing soil compaction
Lowering soil pH
Reducing soil surface evaporation (Correct answer)

Correct answer: Reducing soil surface evaporation

A 2–4 inch mulch layer insulates the soil surface from solar radiation, dramatically reducing evaporation and keeping soil moisture available longer between irrigations.

Question 89: Lion-tailing, an improper pruning practice, refers to:

Over-thinning interior branches so foliage only remains at branch tips (Correct answer)
Removing the central leader
Removing only the tips of all branches
Cutting all branches flush with the trunk

Correct answer: Over-thinning interior branches so foliage only remains at branch tips

Lion-tailing strips interior foliage leaving tufts only at branch ends, which reduces photosynthetic area, increases wind-sail leverage, and leads to branch failure.

Question 90: Topping a tree (indiscriminate cutting of main branches) is considered harmful primarily because it:

Prevents fruit production for one season
Reduces tree height permanently
Eliminates all flower buds
Creates large wounds that decay and stimulates vigorous watersprouts (Correct answer)

Correct answer: Creates large wounds that decay and stimulates vigorous watersprouts

Topping leaves large, poorly sealed wounds prone to rot and triggers rapid, weakly attached watersprout regrowth that creates long-term structural hazards.

Question 91: Proper head-to-head coverage in a sprinkler design means:

Each head's throw radius reaches the adjacent head (Correct answer)
Heads overlap by 75% of their radius
Each head sprays double the distance between heads
Each head covers exactly its rated square footage

Correct answer: Each head's throw radius reaches the adjacent head

Head-to-head coverage ensures each sprinkler's spray reaches the next head, providing uniform overlap and preventing dry spots between heads.

Question 92: The 'one-third rule' in turfgrass mowing states that you should never remove more than one-third of the:

Total root mass in a single season
Annual fertilizer budget at once
Lawn area in one mowing session
Leaf blade height in a single mowing (Correct answer)

Correct answer: Leaf blade height in a single mowing

The one-third rule states that no more than one-third of the leaf blade should be removed in a single mowing to minimize plant stress and protect photosynthetic capacity.

Question 93: Which of the following is considered a best management practice (BMP) for reducing stormwater runoff pollution?

Overwatering landscapes
Installing rain gardens (Correct answer)
Applying synthetic pesticides frequently
Using impervious pavement

Correct answer: Installing rain gardens

Installing rain gardens is considered a best management practice (BMP) for reducing stormwater runoff pollution. Rain gardens are specially designed depressions planted with native vegetation that collect and absorb stormwater from impervious surfaces. This allows water to infiltrate the soil, filtering out pollutants and reducing the volume and velocity of runoff that enters natural waterways.

Question 94: What is the primary purpose of core aeration in turfgrass management?

To introduce new grass seed
To reduce thatch accumulation
To increase soil pH
To relieve soil compaction and improve air, water, and nutrient movement (Correct answer)

Correct answer: To relieve soil compaction and improve air, water, and nutrient movement

Core aeration removes plugs of soil to relieve compaction and improve the movement of air, water, and nutrients to the root zone.

Question 95: Which ANSI standard provides guidelines for tree pruning practices used by professional arborists and horticulturists in the US?

ANSI C57
ANSI A300 (Correct answer)
ANSI Z133
ANSI B18

Correct answer: ANSI A300

ANSI A300 is the industry standard for tree care operations, including pruning specifications, while ANSI Z133 covers safety requirements for arboricultural operations.

Question 96: Espalier is a plant training technique that involves:

Training plants flat against a wall or fence in a two-dimensional pattern (Correct answer)
Removing lower branches to expose the trunk
Pruning to create a spherical canopy
Growing plants on trellises in three-dimensional forms

Correct answer: Training plants flat against a wall or fence in a two-dimensional pattern

Espalier trains woody plants flat in horizontal, fan, or geometric patterns against a support, saving space and often enhancing fruit production through improved light exposure.

Question 97: A soil test reports low potassium. Which symptom would you most likely observe on affected plants?

Stunted root growth only
Pale green color of entire plant
Brown scorching along leaf margins of older leaves (Correct answer)
Purple discoloration of young leaves

Correct answer: Brown scorching along leaf margins of older leaves

Potassium deficiency typically causes marginal scorch (brown edges) on older, lower leaves because potassium is mobile and redistributed to younger tissue.

Question 98: Which soil amendment is best for increasing drainage in heavy clay soil?

Compost
Perlite (Correct answer)
Peat moss
Vermiculite

Correct answer: Perlite

Perlite is a lightweight, porous volcanic glass commonly used as a soil amendment to improve drainage and aeration, especially in heavy clay soils. Its irregular shape and porous structure create air pockets, preventing compaction and allowing water to move more freely through the soil. This helps mitigate the poor drainage issues often associated with clay.

Question 99: Which fertilization practice is recommended to reduce nutrient runoff into waterways in the US?

Use split applications and slow-release products (Correct answer)
Apply only foliar sprays
Double the rate to reduce frequency
Apply fertilizer before heavy rain

Correct answer: Use split applications and slow-release products

Split applications and slow-release products reduce nutrient loading in runoff by limiting the amount of soluble nutrients present in the soil at any one time.

Question 100: What is a primary cultural practice to reduce the risk of root rot in plants?

Watering heavily every day
Avoiding overhead irrigation
Planting in poorly drained soils
Ensuring proper drainage in soil or containers (Correct answer)

Correct answer: Ensuring proper drainage in soil or containers

Root rot is a destructive plant disease caused by fungi or oomycetes that thrive in waterlogged, oxygen-deprived soil conditions. Ensuring proper drainage in soil or containers is crucial because it prevents excess water from accumulating around the roots. This allows roots to access necessary oxygen and reduces the anaerobic environment favored by root rot pathogens, thereby promoting healthy root development.

Question 101: When making a three-cut method for removing large tree limbs, what is the purpose of the first undercut?

To seal the wound immediately
To stimulate callus formation
To remove interior deadwood first
To prevent bark from tearing when the limb falls (Correct answer)

Correct answer: To prevent bark from tearing when the limb falls

The first undercut (from below, about one-third through the branch) prevents the weight of the falling limb from stripping bark down the trunk.

Question 102: When is the BEST time to apply granular fertilizer to established deciduous trees in the US?

During drought stress
Immediately after heavy pruning
Late fall after leaf drop or early spring before bud break (Correct answer)
Mid-summer during peak heat

Correct answer: Late fall after leaf drop or early spring before bud break

Late fall or early spring applications allow nutrients to become available as roots resume active growth without stimulating lush growth that can be damaged by late frosts.

Question 103: A smart irrigation controller adjusts run times automatically based on:

Manual input from the homeowner daily
The age of the irrigation system
Number of plants in each zone
Local weather data such as temperature, wind, and ET (Correct answer)

Correct answer: Local weather data such as temperature, wind, and ET

Smart (weather-based or ET) controllers use local climate data to calculate actual plant water needs and adjust schedules daily without manual changes.

Question 104: Which statement about turfgrass dormancy is correct?

Cool-season grasses can go dormant in summer heat; warm-season grasses go dormant in cool winters (Correct answer)
Dormancy only occurs in warm-season grasses, never in cool-season species
Dormant turf should be heavily irrigated to force it out of dormancy quickly
Dormancy always indicates permanent turf death and requires reseeding

Correct answer: Cool-season grasses can go dormant in summer heat; warm-season grasses go dormant in cool winters

Cool-season grasses can enter summer dormancy during heat and drought stress, while warm-season grasses turn brown and go dormant when temperatures drop in fall and winter.

Question 105: Which soil pH range is generally considered optimal for most turfgrasses?

8.5–9.5
4.5–5.5
7.5–8.5
6.0–7.0 (Correct answer)

Correct answer: 6.0–7.0

Most turfgrasses perform best at a soil pH of 6.0–7.0, which optimizes nutrient availability and supports beneficial soil microbial activity.

Question 106: Which grafting method is commonly used for top-working (reworking) established fruit trees with new scion wood?

Cleft grafting (Correct answer)
Approach grafting
Splice grafting
Budding (T-budding)

Correct answer: Cleft grafting

Cleft grafting is used to graft scion wood onto large-diameter stubs of established trees, making it the standard method for top-working fruit trees to new varieties.

Question 107: The practice of pinching herbaceous annuals and perennials promotes:

Earlier dormancy
Deeper root growth
Bushier habits and more branching (Correct answer)
Taller, faster growth

Correct answer: Bushier habits and more branching

Removing the growing tip (pinching) breaks apical dominance, stimulating lateral bud development and producing a fuller, more compact plant with more flowers.

Question 108: Identify the plant known for its trifoliate leaves and seasonal color change.

Japanese Maple (Acer palmatum)
Poison Ivy (Toxicodendron radicans) (Correct answer)
Virginia Creeper (Parthenocissus quinquefolia)
Red Clover (Trifolium pratense)

Correct answer: Poison Ivy (Toxicodendron radicans)

Poison Ivy (Toxicodendron radicans) is famously identified by its trifoliate leaves, meaning each leaf consists of three leaflets. While it's known for causing an itchy rash, it also exhibits a distinct seasonal color change, turning vibrant shades of red, orange, or yellow in the fall before dropping its leaves. This combination of three leaves and fall color is a key identifier.

Question 109: Air layering is a propagation method best suited for:

Separating bulb offsets
Producing seedlings under grow lights
Rooting a stem while still attached to the parent plant (Correct answer)
Propagating fine-rooted annual species

Correct answer: Rooting a stem while still attached to the parent plant

Air layering wounds a stem on the parent plant, packs the wound with moist sphagnum, and wraps it to encourage roots to form before the new plant is severed.

Question 110: Which pruning cut removes a branch back to a lateral branch or bud, encouraging outward growth?

Pollarding cut
Thinning cut (Correct answer)
Deadheading cut
Heading cut

Correct answer: Thinning cut

A thinning cut removes a branch to its point of origin at a larger branch or trunk, maintaining natural form and redirecting growth without stimulating dense regrowth.

Question 111: Which soil texture typically requires the most frequent irrigation due to its low water-holding capacity?

Clay
Silt loam
Sandy (Correct answer)
Silty clay loam

Correct answer: Sandy

Sandy soils have large pore spaces that drain rapidly, holding little plant-available water between irrigations and requiring more frequent but smaller applications.

Question 112: Grafting is a vegetative propagation technique primarily used to:

Produce plants from seed quickly
Combine desirable scion traits with rootstock vigor, disease resistance, or adaptability (Correct answer)
Induce polyploidy in ornamentals
Eliminate the need for pruning

Correct answer: Combine desirable scion traits with rootstock vigor, disease resistance, or adaptability

Grafting unites a scion (desired cultivar) with a rootstock chosen for vigor, soil adaptation, pest resistance, or size-controlling properties, combining the best traits of each.

Question 113: Compost is valued as a soil amendment partly because it improves nutrient retention. This is mainly due to its contribution of:

Cation exchange capacity via humus (Correct answer)
Rapid nitrogen release
Inorganic minerals
High phosphorus content

Correct answer: Cation exchange capacity via humus

The humic substances in finished compost carry significant negative charge, increasing CEC and the soil's ability to hold cations against leaching.

Question 114: When is the best time to seed cool-season grasses in the northern United States?

Midwinter (December–January)
Late summer to early fall (August–September) (Correct answer)
Early spring (March–April)
Midsummer (June–July)

Correct answer: Late summer to early fall (August–September)

Late summer to early fall provides optimal soil temperatures for cool-season grass germination and allows establishment before the onset of winter.

Question 115: A hardiness zone map (such as the USDA Plant Hardiness Zone Map) is based primarily on:

Average annual minimum winter temperatures (Correct answer)
Annual rainfall averages
Frost-free days per year
Elevation above sea level

Correct answer: Average annual minimum winter temperatures

The USDA Plant Hardiness Zone Map divides North America into zones based on the average annual extreme minimum temperature, used to predict which plants can survive winter.

Question 116: Slow-release fertilizers benefit landscape plants primarily because they:

Increase salt index immediately
Reduce leaching and provide sustained nutrition (Correct answer)
Lower soil pH rapidly
Eliminate the need for micronutrients

Correct answer: Reduce leaching and provide sustained nutrition

Slow-release fertilizers break down gradually, reducing nutrient leaching and providing a steady supply of nutrients over weeks or months.

Question 117: What is the primary advantage of sodding over seeding when establishing a new lawn?

Sodding provides instant, erosion-resistant coverage while seeding takes weeks to months to establish (Correct answer)
Sodding uses exclusively warm-season grasses while seeding uses cool-season types
Seeding is always more expensive per square foot than sodding
Sod cannot be used on slopes greater than 3:1

Correct answer: Sodding provides instant, erosion-resistant coverage while seeding takes weeks to months to establish

Sodding provides immediate ground cover and erosion control, while seeding requires significantly more time for germination and establishment.

Question 118: The purpose of a grading plan in landscape installation is to:

Indicate lighting fixture locations
Define finished elevations and direct surface water drainage (Correct answer)
Show plant species selection
Specify irrigation head placement

Correct answer: Define finished elevations and direct surface water drainage

A grading plan establishes finished grades, slopes, and drainage patterns to ensure water moves away from structures and toward appropriate drainage features.

Question 119: Irrigation scheduling based on soil moisture sensors is preferred over calendar-based scheduling because it:

Eliminates the need for a controller
Works without any maintenance
Is always less expensive to install
Applies water only when plants actually need it, reducing overwatering (Correct answer)

Correct answer: Applies water only when plants actually need it, reducing overwatering

Soil moisture sensors measure actual water content in the root zone, allowing irrigation to trigger only when plants need water rather than on a fixed schedule regardless of conditions.

Question 120: Proper irrigation timing for turfgrass is generally recommended during which part of the day?

Midafternoon when evaporation rates are at their highest
Late evening after sunset to maximize overnight soil moisture
Early morning to minimize evaporation and reduce fungal disease risk (Correct answer)
Midday to cool the grass canopy during peak temperature stress

Correct answer: Early morning to minimize evaporation and reduce fungal disease risk

Early morning irrigation minimizes evaporative loss, allows foliage to dry during the day to reduce disease pressure, and delivers water when plant demand is increasing.

Question 121: What is the primary advantage of using reclaimed (recycled) water for landscape irrigation in the US?

Higher pathogen load benefits soil biology
Eliminates need for fertilization
Provides higher water pressure
Conservation of potable drinking water supplies (Correct answer)

Correct answer: Conservation of potable drinking water supplies

Reclaimed water is treated wastewater that would otherwise be discharged; using it for irrigation reduces demand on potable water supplies and can supplement plant nutrients.

Question 122: The union between rootstock and scion in a successful graft is formed by the activity of which tissue?

Cambium (Correct answer)
Phloem only
Xylem only
Epidermis

Correct answer: Cambium

The vascular cambium layers of rootstock and scion must be aligned so that callus tissue and new vascular connections form, creating a functional graft union.

Question 123: Which nutrient application timing is most appropriate for promoting flower and fruit development?

High phosphorus prior to flowering (Correct answer)
High nitrogen during fruiting
High nitrogen in early spring
High calcium after harvest

Correct answer: High phosphorus prior to flowering

Phosphorus supports energy transfer (ATP) and promotes flower initiation and fruit set, making pre-bloom application the optimal timing.

Question 124: A landscape contractor following best management practices (BMPs) for erosion control on a new installation should first:

Install perimeter erosion controls (silt fencing, wattles) before grading begins (Correct answer)
Plant grass seed over the entire site
Apply herbicides to clear existing vegetation
Compact the soil to prevent movement

Correct answer: Install perimeter erosion controls (silt fencing, wattles) before grading begins

Perimeter erosion controls must be installed before any soil-disturbing activities to capture sediment before it can leave the site and enter waterways.

Question 125: Auxin (IBA or NAA) is applied to stem cuttings to:

Harden off the cutting before transplanting
Promote adventitious root formation (Correct answer)
Prevent fungal infection
Speed shoot growth after rooting

Correct answer: Promote adventitious root formation

Indole-3-butyric acid (IBA) and naphthaleneacetic acid (NAA) are synthetic auxins that stimulate the formation of adventitious roots at the base of cuttings.

Question 126: What is a significant advantage of using compost in sustainable horticulture?

Requires heavy machinery for application
Decreases soil organic matter
Increases water runoff
Reduces the need for synthetic fertilizers (Correct answer)

Correct answer: Reduces the need for synthetic fertilizers

Compost is a rich organic material that significantly enhances soil fertility and structure in sustainable horticulture. By providing a slow-release source of essential nutrients and improving the soil's water retention and microbial activity, compost reduces the need for synthetic chemical fertilizers. This promotes healthier plant growth while minimizing the environmental impacts associated with chemical inputs.

Question 127: What does the term 'transition zone' refer to in turfgrass management?

A strip of turf that is currently undergoing a renovation from one species to another
The boundary between a Kentucky bluegrass stand and a tall fescue planting
A geographic region of the mid-United States where neither cool-season nor warm-season grasses are fully adapted (Correct answer)
The grassy border area between a lawn and an adjacent garden bed

Correct answer: A geographic region of the mid-United States where neither cool-season nor warm-season grasses are fully adapted

The transition zone is a geographic band across the middle United States where summer heat stresses cool-season grasses and winter cold damages warm-season grasses, creating difficult management conditions.

Question 128: Which landscape feature is most effective for managing stormwater runoff on residential properties?

Raised decking over lawn
Expanded concrete driveways
Rain gardens (bioretention areas) (Correct answer)
Conventional turf with underground drainage

Correct answer: Rain gardens (bioretention areas)

Rain gardens are shallow, planted depressions that capture and infiltrate stormwater runoff, reducing peak flow, filtering pollutants, and recharging groundwater.

Question 129: A distribution uniformity (DU) test for a sprinkler system measures:

Water pressure at each head
How evenly water is applied across the irrigated area (Correct answer)
Soil moisture at various depths
Flow rate from each emitter

Correct answer: How evenly water is applied across the irrigated area

DU compares catch-can volumes across the irrigated zone to determine how uniformly water is distributed; low DU indicates dry spots requiring over-irrigation elsewhere.

Question 130: Runners (stolons) are a natural vegetative propagation structure found in which common landscape plant?

Strawberries and many lawn grasses (Correct answer)
Hostas
Ornamental cabbages
Tulips

Correct answer: Strawberries and many lawn grasses

Strawberries and turfgrasses such as bermudagrass and St. Augustinegrass produce stolons — horizontal above-ground stems that root at nodes, naturally propagating the plant.

Question 131: Photoperiod manipulation in propagation greenhouses is used to control:

Rooting hormone effectiveness
Nutrient uptake rates
Seed stratification
Flowering time of long-day and short-day plants (Correct answer)

Correct answer: Flowering time of long-day and short-day plants

Artificially extending or interrupting the night length with supplemental lighting or black cloth allows growers to trigger or delay flowering in photoperiod-sensitive species year-round.

ASHS Certified Horticulturist (CH) Examination

The ASHS Certified Horticulturist (CH) exam tests competency across seven horticultural domains including landscape design, plant production, propagation, pest management, and business practices. Administered by the American Society for Horticultural Science, it validates professional-level knowledge for practicing horticulturists.

200

Questions

240 min

Time Limit

70%

To Pass

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