CSLB C-27 Landscaping ContractorPlanting and LandscapingMedium
A landscape contractor is installing a new tree in a compacted urban soil environment. To maximize the tree's long-term health and establishment, which planting technique is most appropriate for addressing the compacted soil?
- AAmending the entire planting hole with 50% organic matter and 50% native soil.
- BCreating a wide planting hole, loosening the sides, and planting slightly high with a root flare exposed.
- CDigging a narrow, deep planting hole to encourage deep root growth.
- DPlanting the tree at the same depth as it was in the nursery container, backfilling with native soil.
Show answer & explanationAnswer & explanation
Correct answer: B. Creating a wide planting hole, loosening the sides, and planting slightly high with a root flare exposed.
In compacted soils, a wide planting hole with loosened sides allows roots to spread more easily. Planting slightly high with the root flare exposed prevents stem rot and encourages roots to grow outwards into better-drained, aerated soil, which is critical for long-term health in poor soil conditions.
Why the other options are wrong
- A. Amending only the planting hole can create a 'bathtub effect' where water collects, and roots are reluctant to leave the amended soil, circling within the hole.
- C. A narrow, deep hole restricts lateral root growth, which is essential for tree stability and nutrient uptake, especially in compacted soil.
- D. Planting at the same depth in compacted soil can lead to poor drainage and suffocated roots; the root flare should be exposed.
Tree Planting in Compacted Soil
Techniques used to ensure healthy tree establishment in soils with poor aeration and drainage, often involving wider planting holes and careful attention to root flare exposure.
- Compacted soil restricts root growth and water infiltration.
- Wide planting holes encourage lateral root spread.
- Root flare (where roots meet the trunk) must be at or slightly above grade.
- Avoid excessive amendment of only the planting hole to prevent 'bathtub effect'.
Memory trick: Wide, Loose, High: Give roots room, break the walls, show the flare!