Tree establishment irrigation research at the University of Florida

Edward F. Gilman, Professor , Environmental Horticulture

Trees are irrigated up to 21 times each week in some nurseries.
Live oak trees (2.5" trunk diameter) watered regularly 2 to 3 times each week take about 12 months to establish their roots in the landscape. Bigger trees take longer.
For bare minimum survival, 2.5" diameter live oak planted in spring need water twice weekly for about 10 weeks, then no irrigation is needed provided normal rains begin.
You cannot make up for lack of frequency by applying large volumes of water infrequently.
Soil amendments in the backfill soil do not help reduce tree irrigation requirements.
It is better to apply irrigation frequently in the weeks and months immediately after planting trees then to apply the same volume over a longer period.
There is no data demonstrating that native trees or shrubs can get by with less water than non-natives after transplanting to the landscape.
Survival can be improved and water use reduced by using low volume irrigation technology.

Research-based irrigation requirements for trees other than live oak
Irrigation recommendations in extended drought; our studies were all done in more-or-less normal years.
Effect of plant size on irrigation requirements.
Effects of season on irrigation requirements.