On December 19, Dr. Jim Foret (pictured above), a retired environmental scientist from the University of Louisiana at Lafayette and a horticulturalist, demonstrated “root pruning” using small trees at the Frozard community garden near Arnaudville. Root pruning is a technique used to limit the volume of the root ball and stimulate root growth prior to transplanting. ANPP can use this technique to prepare small in-the-ground trees for potting into containers and later sale.
Root pruning is best done in Fall or during Winter dormancy. Use a sharp shovel to cut straight down (90 degrees to the soil surface) and all around the tree about 8-12 inches from the trunk. If root pruning is done before Winter dormancy, the tree should be watered periodically in the absence of rain to prevent the roots from drying out. Trees root pruned during early Fall or during the growing season can be potted or transplanted about 3 months following root pruning; this will give plants enough time to recover and increase root density. It would be best to move trees root pruned during dormancy the following Winter.
Whether you're digging up trees now or root pruning for next year:
Always use clean, sharp tools to avoid breaking roots; plants will heal better if the shovel cleanly slices through the roots. The blade of the shovel should always be aligned vertically (90 degrees to the soil surface) to make each slice.
Realizing the benefits of root pruning requires time and planning. A plant requires time to respond to pruning (i.e., growing a more dense, compact root system) before it is transplanted. Plan accordingly. For example, if you want to transplant a tree during dormancy (November – February), plan to do root pruning the Winter before. Root pruning in August would give the plant at least three months to increase root density before dormancy sets in, but this would be a stressful time of the year for pruning and less than ideal.
Transplanting bare-root trees or shrubs during Winter dormancy is really easier than root pruning. The success rate of using bare-root plants can be high, as long as the roots are kept moist. An advantage of bare-root plants is their lighter weight than container plants.
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