C27 LICENSE Cheat Sheet 2026

The 30 highest-yield C27 LICENSE facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is the purpose of a rain sensor or weather-based controller in an irrigation system? → To automatically shut off irrigation during or after rainfall
2. When performing a 'rejuvenation pruning' on a severely overgrown, multi-stemmed deciduous shrub, what is the recommended practice? → Cut all stems down to about 6-12 inches from the ground in late winter or early spring.
3. What is the primary visual indicator of powdery mildew on landscape plants? → White to grayish powdery coating on leaf surfaces and stems
4. Does the $500 project value limit include both labor and materials? → Yes, both labor and materials are included in the total project value.
5. What is the primary purpose of applying a 3-inch layer of organic mulch to all exposed soil surfaces in a newly planted landscape bed? → To retain soil moisture, suppress weeds, and regulate soil temperature.
6. When installing a perforated pipe for a French drain, what is the correct orientation for the drainage holes? → Facing downward, to allow collected water to exit and be carried away.
7. Which insect vector is primarily responsible for spreading citrus greening disease (Huanglongbing) to citrus trees? → Asian citrus psyllid (Diaphorina citri)
8. Who benefits from the contractor’s bond? → The client, for financial recovery.
9. Under California law, which document must a landscaping contractor possess before applying restricted-use pesticides (RUPs)? → A Qualified Applicator License (QAL) or certificate from the CDFA
10. What does 'water budget' mean in the context of California landscape water regulations? → The maximum annual water allowance for a landscape based on local ET data
11. What is required for the contractor’s bond in the C-27 application process? → A bond amount typically set at $15,000.
12. During a grading operation on a windy day, what is the contractor's primary responsibility regarding airborne particles? → Post signs warning of the dusty conditions.
13. Which plants are most appropriate for drought-tolerant landscaping in California's climate? → Native and Mediterranean-climate plants
14. What should a contractor do if they do not have employees? → Skip the workers' compensation insurance requirement.
15. If an automatic irrigation valve fails to shut off after a watering cycle, what is the most common component to investigate first? → A faulty solenoid or debris in the valve diaphragm.
16. Under California pesticide regulations, how long must pesticide application records be retained by a licensed applicator? → 3 years from the date of application
17. Which irrigation method provides the greatest water conservation in a drought-tolerant landscape? → Drip irrigation
18. Is continuing education required for maintaining a C-27 Landscaping Contractor License? → No, there is no continuing education requirement.
19. Which type of mulch is most effective for conserving soil moisture in drought-tolerant landscapes? → Organic wood chip mulch
20. What is the first step in the application process for a C-27 Landscaping Contractor License? → Submit an application to the Contractors State License Board (CSLB).
21. What additional step must be completed if the applicant has employees? → Submit proof of workers' compensation insurance.
22. What is the legal consequence of contracting in California without a valid license for work valued over $500? → It is a misdemeanor and the contractor loses the right to sue to collect payment
23. What is required to renew a C-27 Landscaping Contractor License? → Submit a renewal application and pay the renewal fee.
24. A landscaping crew is using a wood chipper to dispose of tree trimmings. Which of the following is a critical safety practice required by OSHA? → Using a lockout/tagout system to de-energize the machine before clearing a jam.
25. Which of the following factors is the PRIMARY determinant of friction loss in an irrigation pipe? → The velocity and volume of water flow.
26. Which document must a California contractor provide to a homeowner before starting a home improvement project? → A written contract that includes a three-day right to cancel notice
27. When grading a landscape to ensure proper surface drainage away from a building's foundation, what is the generally accepted minimum slope? → 2% (1/4 inch per foot)
28. Which of the following is an example of a biological control method for managing aphid populations in a landscape? → Releasing or encouraging populations of ladybugs (Coccinellidae)
29. Which California agency is responsible for setting statewide outdoor water use restrictions that affect landscaping contractors? → State Water Resources Control Board
30. What is the primary goal of xeriscaping in residential landscaping? → Reducing water usage through drought-tolerant design