Trees constantly lose water to the atmosphere. Water is the single most limiting essential resource for tree survival and growth. Water shortages severely damage young and old trees alike, and set-up healthy trees for other problems. Drought conditions can lead to tree decline, pest problems, and non-recoverable damage. Supplemental watering can greatly assist in maintaining tree health during droughts – both during the growing season or during the dormant season.
Trees can be old and valuable. They are usually considered non-replaceable beyond 10 inches in diameter. Many associated landscape plants are low cost and easily replaceable. If these plants are damaged or lost to drought, the landscape can be corrected quickly and relatively cheaply. Large, drought-killed trees can not be replaced in two human generations. Please emphasize watering trees during droughts.
Ideally, irrigation should automatically begin when soil moisture reaches some critical measure determined by a moisture probe or soil tensiometers. Trees should be zoned apart from turf and other landscape plants. Careful tuning of irrigation systems are needed to prevent over-watering trees.
Manually, the best ways to water trees are by soaker hose or trickle (drip) irrigation which you turn on and off such as the Tree Sprinkler by WaterKingProducts.com. Even a garden hose, moved often, can provide a good soil soaking although can be time consuming. Use a light organic mulch to conserve moisture and apply water over the top of the mulch.
Deep watering a tree with a pipe or wand stuck into the soil 12-24 inches is not as good for trees as surface applications. Most of the tree’s absorbing roots are in the top foot of soil. Applying water deeper than this level misses the active roots and allows water to drain away from the roots, wasting efforts and water. Apply water across the soil surface and let it soak into the soil. Surface soaking allows tree roots more chances to absorb any water, helps maintain soil health, and helps maintain essential element cycling and transformations in the soil. There are many tree watering products on the market by companies like Bosch watering, Grainger, Teknorapex and Water King Tree Sprinkler @ waterkingproducts.com.