When plant problems occur in the landscape, gardeners often blame insects or diseases. While some plants are more susceptible to pest problems than others, many issues arise when plants are planted too deeply.
In September, I wrote about minding your roots when planting trees and shrubs. Properly grown plants are healthier with fewer problems. Unfortunately, many trees and shrubs are not planted correctly. Even ‘professional’ landscapers are often guilty of improper planting methods due to poor training or education.
The symptoms of deep planting can take 3 to 5 years to appear in the landscape, with problems in extreme cases occurring within a year after planting. Poor planting practices that cause girdling roots may take longer to appear. See A Routine Check-up of Trees Saves Lives and Property for more information about girdling roots.
Symptoms caused by deep planting include chlorotic (yellowing) foliage, poor growth, a thinning canopy, early-onset seasonal color, and slow, general plant decline. Additionally, pest insect infestations or diseases, such as leaf spots, cankers, and dieback, may occur.
The gardenia to the right is chlorotic and has thinning growth because it is planted too deeply.
N. Jordan Franklin, ©2021 HGIC, Clemson Extension
Upon closer inspection, it is apparent the plant is planted too deeply. It needs to be dug up and replanted at the correct depth with the topmost roots at or just below the soil surface.
N. Jordan Franklin, ©2021 HGIC, Clemson Extension
Inspect trees and shrubs to determine if they are planted at the correct depth by following the steps below.
- Pull the mulch away from the trunk to expose the soil. Never leave mulch piled up on the plant. A tree’s root flare should be visible above the ground and mulch. A shrub’s root flare is a little harder to identify.
- If the root flare is not visible, carefully dig the soil away from the trunk to locate the topmost roots. The plant is too deep if the top roots are an inch or more below the soil surface.
- If the plant is too deep, gently pull the soil away from the top of the roots. If roots are more than a few inches below the soil surface, it may be necessary to dig up the plant and replant it at the correct depth. For information about transplanting existing shrubs, visit HGIC 1005 Transplanting Established Trees and Shrubs.
