Regina P. Bracy, Owings, Allen D., Orr, Paul R. | 12/2/2008 2:09:02 AM
When transplanting field-grown and container trees into the landscape, a much smaller root system (to accommodate movement and transport) is being planted than a tree of that same size would naturally have. A significant amount of time is required to establish these newly planted trees in the landscape. Tree establishment refers to the point a newly transplanted tree has grown enough roots into the surrounding soil to keep it alive without supplemental irrigation.
Trees in Louisiana that are regularly irrigated after planting require approximately three months per inch of trunk diameter to fully establish roots in the landscape soil. Trees that are under-irrigated during this establishment period are likely to require additional time to establish because roots grow more slowly. Since most root growth occurs in summer, be sure soil moisture is appropriate during this crucial season.
Irrigation volume requirements are best summarized as 1 to 3 gallons per caliper inch of tree size per irrigation. Based on these recommendations, a 3-inch-caliper tree should receive 3 to 9 gallons of water per application and should be irrigated during the approximately 9-month establishment period. Using the same recommendation, a 10-inch-caliper tree (yes, live oaks this large are sometimes transplanted) should receive 10 to 30 gallons of water per application and will require irrigation for three to four years until established.
Successful establishment of landscape trees is best accomplished with low-volume irrigation on a separate zone so that trees can be irrigated independently from shrubs and turf. Experience has shown that the minimal investment required to install a low-volume system is far outweighed by the transplanting success of trees planted with a drip or bubbler irrigation system. Additionally, low-volume irrigation systems with drip or bubbler heads are often exempt from watering restrictions.
The above information is based on research conducted at the University of Florida. It was originally written by Michael Marshall (Marshall’s Tree Farm) and published in Ornamental Outlook’s email update.
The LSU AgCenter and the LSU College of Agriculture