An unofficial windshield survey shows an alarming level wilting foliage on ornamental and shade trees planted in the last two to three years, along with trees planted this spring. It takes an extended dry period to have tree foliage wilting. It is obvious when flowers, vegetables and our lawns need water, much less obvious for larger wood plants as they do not show wilting until it gets so bad we see off colored wilting leaves.
In all these cases, recovery from being transplanted is not yet complete and the development of an adequate root system to support the tree is lacking. A good rule of thumb is it takes at least one year of recovery and good care per inch of trunk diameter to get that tree "back on its feet" where the root system is able to support the foliage canopy.
The remedy is properly watering those woody trees so they rehydrate and provide additional soil moisture for future uptake. While sprinklers work pretty well for watering the lawn and flowerbeds, larger amounts of water will be needed for our ornamental and shade trees. On new or recently transplanted woody plants, making sure the water gets to the limited root system is key. Watering berms, using watering bags or leaving the hose going at a slow rate of flow near the trunk are all good strategies. Those bags will be empty in about 24 hours so they will need to be refilled at least once a week or more, depending on rainfall, soil types and the size of transplanted tree.
Needled evergreen trees can be seen in all stages of decline, from just beginning to lose needles on lower limbs to those in advanced stages, leading to death. The need in the home landscape is to focus on younger seemingly healthy needled evergreens, as it is too late for the others. The needed watering routine is the same as deciduous trees with one addition for evergreens – a late to very late fall watering should be done to help insure plenty of soil moisture during the winter months.
A final point about water. Even if you have established shade and evergreen trees that appear healthy, you want to keep them that way. Watering berms and watering bags are impractical, using the open garden hose at a good rate of flow to provide lots of water and at the same time not run off to other areas of the yard or the curb does work well. Put that water in the drip zone at the edge of the tree's canopy. Watering once a month is not out of the question.
About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.