I purposely did not go back and count how many times this season I have discussed water. Either we are getting too much, it is interfering with planting, or we are in absolute need of water. Recent weather patterns have brought much needed rain to some of us, but others were left dry.
Master Gardener Help Desks continue to get visitors and calls about failing plants. Large evergreens and older shade trees have issues since the drought of 2012 and continue to show signs of stress, long-term decline and eventual death. Homeowners can see this visually in the rates of annual growth and the size of foliage on the trees. It will show up in the spring as terminal branch and twig dieback too. Some deciduous trees will manage water loss by allowing some of the foliage to yellow and fall to the ground. Birch trees are a good example of this. They also will drop damaged leaves from the Japanese beetle, so both are happening right now. If a tree has been lost, you can likely see the decline by looking at the annual rings after the tree is down. More recent rings are closer together compared to those pre-2012. Shade trees, shrubs and evergreens do not show water stress like other plants and that's' why it is easy to think they are OK.
Perennials in the beds will show stress by wilting during the day and recovering by morning, only to wilt again if water is not supplied. Blooms will not last as long and will not have the quality you expect. Full sun perennials will wilt before plants in the shade, but eventually those perennials, including ground covers, will wilt.
If the lawn is the problem, the best time to renovate between August 15 and the first week in September. This puts the renovation in a timeframe when the weather will only be getting better for lawns as we move to cooler and better moisture conditions. If weed control is going to be part of the renovation, even the weeds need to be actively growing for control products to work well. Fall weed control can be done into October, if necessary. Water will be key for the revival of dormant grass plants and the germination of seed if over-seeding or reseeding selected spots.
Related to the drought is the fact that while Japanese beetles are moving from the feeding portion of their life cycle to one of egg laying, the very hard dry soil will limit egg laying and for those eggs that do hatch, the ability to acquire enough food to survive the winter. If there has not been a history of grub damage, the rule of thumb is it takes more than 12 grubs per square foot before real damage is done to the lawn.
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.