Root pruning container plants

Steve and Val Bradley explain how avoid repotting to ever-larger containers

- Steve and Val Bradley

ROOT pruning trees and shrubs growing in containers is used to reduce the need to keep transferring these plants to ever-larger pots, which would eventually lead to the container being so big it would become unmanageable.

Where a plant is intended to remain in a container for a long time, the usual recommendation is to remove the top 2-3in (5-7cm) of old compost each spring and replace it with fresh bought compost containing a controlled-release fertiliser. This should provide sufficient nutrition for the current growing season. This is an alternative to constantly moving the plant into a larger container.

Roots close to the surface

Removing the old layer of compost does have advantages, including the removal of weeds and weed seeds, along with the eggs and grubs of the dreaded vine weevil. Also, because there needs to be a balance of the plant hormones found in both the roots and top growth of a plant, this minor form of root pruning can be used to check the vigour of a plant and, in some cases, to encourage better flower and fruit production.

The problem occurs when the roots are on, or close to, the surface of the compost, making it very difficult to remove this spent layer of old compost.