On the Casey Tree Farm, a new project of ours in Clarke County, Virginia, we are planting thousands of trees that will one day find a home on the streets of D.C. As a part of planting and cultivation efforts, we are working on innovative ways to prepare healthy and long-lasting trees. One method our staff is working with is drip irrigation to keep acres of trees watered. Drip irrigation conserves water by eliminating run-off and generates a lower rate of evaporation. Since the number of trees on the farm more than doubled this spring, so did the amount of tubing to keep them irrigated. In one hour, 0.42 gallons of water gets pumped through 24,000 feet of tubing to drip into 3,600 total trees.
The irrigation system at the Casey Tree Farm uses local well water. Even though it is cleaner water, it still has to be filtered to remove sediments that could clog the irrigation tubes. After flowing through the filter, the water goes through a pressure regulator to keep pressure constant. We use it at scale on the farm, but homeowners in an urban environment can incorporate drip irrigation into their landscaping plans at a reasonable cost. We employ a similar drip irrigation system to care for the bioretention planter at our headquarters in D.C.
Aside from the drip-irrigated acres of trees, we are also testing a system for growing bare-root trees – these trees are different from the balled and burlapped trees you may be familiar with from Casey Trees plantings because they do not have a root ball surrounding the roots. The root system is exposed which allows for more portable trees that are less likely to have problematic root systems that we sometimes encounter with balled and burlapped or containerized trees. We grow these bare-root trees in a Missouri Gravel Bed. Created by Professor Chris Starbuck at the University of Missouri in 1985, this method consists of dormant, bare-root trees that are planted in the spring with their roots in an irrigated planter box filled with gravel and held for up to a year before planting.
We are currently growing 70 trees in a 30 x 30 feet, 16 inch deep Missouri Gravel Bed, which are watered twice daily for fifteen minutes with a sprinkler system. When the summer heat sets in, the trees will be watered four times a day for a shorter period of time. Since the trees are set in porous gravel and not soil, the water is not retained and needs to be replenished. However, the gravel is rich in minerals and nutrients, and the farm staff is eager to see how the trees do once transplanted.
Learn more about our tree growing efforts at the Casey Tree Farm nursery.