Key Features
- Roots growing tout of stems
- Decline of annual or perennial
- Common drought symptoms
Symptoms
This problem may be simply identified by observing any roots pushing out of the bottom of the pot. Prior to purchase, hold the pot upside down and remove the pot from the plant to examine roots. If a tremendous number of roots are visible, the plant may be rootbound. To encourage new, healthy root growth, the bound roots must be broken up. Certain vigorous annuals and perennials are often potbound when purchased late in the season.
Biology
Severely potbound plants often "strangle" themselves during the process of vigorous growth. Affected roots grow in a circular, dysfunctional pattern which causes stem compression, basically cutting off its own ability to transport nutrients and water. Often these girdling roots are the results of improper planting techniques and poor root formation in the nursery or greenhouse. This, in turn, predisposes the plant to opportunistic pathogens and insects, and can prevent good establishment in the landscape.
Management Recommendations
There are several approaches to dealing with potbound annuals and perennials. Although plants with rotting roots and severely potbound plants should be avoided, few people can pass up a bargain plant at the end of the season! First, soak the plant in water for several hours to soften the roots, and deeply water the plant (and prepare it for the stress to come). If possible, remove the plant from the pot, "untangle" the roots and spread them out. Rub fingers across the surface of the roots to loosen and untangle the binding of the roots. Remove the bottom inch of roots with a sharp knife, razor blade or box cutter. If the plant is severely potbound, use a box cutter or razor blade and score the root ball every few inches to break up the root clump. The depth and frequency of the cutting is related to how potbound the plant is (more potbound, more cutting). Then use fingers to loosen roots. Remove any dead or discolored roots. Examine the remaining roots and evaluate the above-ground portion to the roots. Cut back the above-ground portion to make the amount of roots comparable to the amount of shoots. Don't worry--they will recover! Make sure plants are well watered to establish.
Effective Pesticides
Pesticides are neither available nor recommended for managing this condition.
Resources
- Not satisfied with ID? Contact the Purdue Plant and Pest Diagnostic Lab
- Sign Up for the Purdue Landscape Report
