How to Water Trees, Shrubs & Groundcovers

Posted on April 12th, 2015 by John Foegley

Providing balanced moisture levels is critical to the establishment of all newly installed plant material and it is the responsibility of the home or business owner, unless Foegley Landscape is specifically contracted to provide this service. The amount and type of supplemental irrigation will depend on several factors including soil type, shade, slope, plant type & amount of natural rainfall.

Monitoring Soil Moisture

Visual inspection of plant material is not an accurate or sufficient method for monitoring the moisture level for planting beds. The visual symptoms of over watering can be very similar to lack of water.

Monitoring soil moisture is the first and most important step when providing supplemental irrigation. Using a hand trowel or shovel, dig down 6-7″ inches to check for moisture. Soil should be moist to the touch, but not muddy. Too much water is just as bad as lack of water, so if muddy or saturated conditions are found, stop supplemental water until the soil has dried out.

Automatic Irrigation Systems

When automatic irrigation zones cover planting beds monitoring for moisture becomes even more important. Planting beds can easily become over watered if an automatic system is set and not adjusted for natural rainfall or lack thereof. It would not be unusual to adjust an automatic system weekly during the first season after a new landscape installation.

When the same zone covers trees, shrubs and groundcovers managing water amounts becomes very difficult. Turf areas typically take more water than ornamental trees, shrubs, groundcovers and perennials. Unfortunately this means when the turf is getting adequate water, trees and shrubs are being over watered. And if the system is set for the trees and shrubs, the turf will probably be underwatered. This problem is exacerbated by poorly draining soils.

Hand Watering

The most effective way to hand water is to simply place a hose at the base of the tree or shrub and let the water trickle at a rate which is absorbed into the ground without run off. The time needed to penetrate will vary depending on the water flow rate, size of tree and dryness level and surrounding soil type. In general, time will vary between 15 minutes and several hours. See Purdue recommendations for monitoring watering amounts using a lawn sprinkler.

Watering Ornamental Trees & Shrubs

(Excerpt from Planting Trees & Shrubs – Purdue University – Michael Dana)
The most important factor in caring for newly planted trees and shrubs is water. You must provide the correct amount of water, because overwatering is just as injurious as underwatering. The soil type and the amount of rainfall will determine the frequency and amount of water needed.

On well drained soil, apply 1 inch of water per week during the summer and fall. On sandy soils, at least 2 inches of water per week are needed, preferably in two applications of 1″ each. Poorly drained, clay soils will require less frequent watering.

Water regularly and supplement normal rainfall. Don’t just sprinkle by using light waterings. A brief rain shower of ½ inch should be supplemented by additional watering. If a heavy rain occurs (2 or more inches), additional watering may still be needed the following week, not in two weeks. Using a lawn sprinkler, place a straight sided can near a tree ir shrub and water until the can contains one inch of water.

For more information on Watering Trees and Shrubs from Clemson University, click HERE.