Summer has an intriguing way of luring in longer days, sunnier skies, and vibrant landscapes. For many, summer is a calming retreat after enduring what felt like an endless winter. Naturally, with heat waves we feel inclined to water our trees regularly, but it’s easy to get carried away and over-water. While we have suffered through drought conditions here in the Heartland, other areas have had to deal with heavy rainfall, even flooding. The following are a few rules of thumb to keep in mind when watering your trees.
With differing climates and varying landscapes, it’s hard to quantify how much water trees need because irrigation will vary from one species to the next. Young trees and those transplanted will call for more water because they’re burning lots of energy establishing their roots in the soil.
For young trees we encourage a deep-watering by running the hose over the root zone for about 30 seconds. The idea is to reach the full root depth and keep the soil damp, not soggy. Mature trees are best left to nature; unless you’re suffering from severe drought conditions, let your rainfall do the watering. Be cautious not to overwater, as it can drown the tree roots. If a puddle remains after watering then take it as a sign of too much watering. Other signs to look for include yellow leaves, usually starting on the lower branches, wilting, brittle green leaves, or fungus growing on soil surface. If your soil is wet and you notice any of these changes, you may be overwatering your trees.
A soil probe is helpful in learning how dry or saturated your soil is and can set the tone for watering frequency.You can also test soil moisture by hand. If a planting site is properly hydrated you should be able to compress the soil into a ball that will crumble when gently rolled between the palms of your hands. No need to dig deep, one to two and a half inches below ground level is sufficient in testing the moisture content.
Ooze tubes—an automated drip irrigation system— are another great method for controlling water time and ensuring your trees are receiving adequate water.
Mulching is a great practice to implement in tree care, especially if you’re dealing with drought conditions. Mulch retains water, helping to keep roots moist. Another tip to avoid drying out soil during times of drought is to stay away from commercial potting soils and fertilizers. Salts and other additives in fertilizers such as Miracle-Gro can cause root burn, adding additional stress to trees. Proper tree pruning improves limb stability and structure, and removes dead branches, which decreases tree tension and allows water to move where needed most in the tree. Also, avoid digging holes in the ground as an effort to water deeply; it will only dry out the roots even more.
With your help, the season of sun can work in favor of your trees. You can read up on other great ways to save water in our How to Landscape to Save Water Tree City USA bulletin. What other tips do you practice in keeping trees appropriately watered during the summer season?