CSLB C-27 Landscaping ContractorPlanting and LandscapingMedium
A landscape contractor is preparing to plant several 15-gallon trees on a new construction site. The soil analysis indicates compacted clay with poor drainage. What is the most effective planting technique to ensure the long-term health and stability of these trees?
- ADigging a planting hole only slightly larger than the root ball to maintain soil structure around the roots.
- BDigging a planting hole twice the width of the root ball and amending the backfill with 50% organic matter.
- CCreating a raised planting mound with well-draining soil, ensuring the root collar remains above grade.
- DInstalling a subsurface drainage system around each tree and backfilling with native clay soil.
Show answer & explanationAnswer & explanation
Correct answer: C. Creating a raised planting mound with well-draining soil, ensuring the root collar remains above grade.
Compacted clay with poor drainage is detrimental to tree roots. Creating a raised planting mound with well-draining soil elevates the root ball, improving drainage and aeration, which is crucial for tree establishment in such conditions. Ensuring the root collar is above grade prevents rot.
Why the other options are wrong
- A. A hole only slightly larger than the root ball does not adequately address severe compaction and poor drainage, restricting root growth.
- B. While beneficial for width, amending backfill in a clay 'bathtub' can create drainage issues where water pools around the roots. The ratio of organic matter might be too high.
- D. Installing subsurface drainage can be complex and expensive; a raised mound is a more practical and often more effective solution for individual trees in severe clay.
Raised Mound Planting
A planting technique where trees or shrubs are planted on an elevated mound of soil to improve drainage and aeration, especially in heavy clay or waterlogged areas.
- Prevents root rot.
- Improves oxygen availability to roots.
- Commonly used in poorly drained soils.
Memory trick: When clay is a 'bathtub,' build a 'hill' for roots.