Your
YARD AND GARDEN

Dave Robson

July and August are usually scorchers. Those lazy, hazy, crazy days of summer tend to promote some laziness on most gardeners' part. It gets so hot that everyone soon wishes for the coolness of winter. Isn't it interesting that during winter we wish for summer's warmth? Most of us are hard to please, I guess.

The landscaping takes a beating during the hot summer months. More plants die during the summer than any other time of the year. Heat and lack of water are the two main culprits.

Heat is a double-edged sword for plants. High temperatures cause the leaves to lose a tremendous amount of water in order to stay cool and carry out the growing functions of the plant. A tree with an 80-foot spread may lose more than 80 gallons of water per DAY when the temperatures are in the 90s. That's the amount of water that can go through two to four cycles of a washing machine. Again, that's per day.

Fortunately, the soil holds lots of water and roots are adept at extracting it. We seldom see large trees wilt since roots are deeper and able to get to water. Remember, though, that roughly 80 to 95 percent of tree roots are within the top 15 inches of the soil surface.

The top inch or so of soil dries the fastest. Warm, dry spells early in the season encourage deep root growth in search of moisture. Cool, wet weather like many of us have experienced this year and to some extent last year, tends to keep the roots near the surface. When the temperatures increase, roots don't have the time to search out water (go deeper) and plants wilt quickly.

Heat is also detrimental to root growth. Cool temperatures in the 40s, 50s, or 60s are ideal for most plants. Soil temperatures in the 80s and 90s essentially stop root growth. This is one of the main things to consider when transplanting trees and shrubs during the hot part of summer. You may want to avoid transplanting then.

Watering isn't always practical or economic in the landscape. Many rural landscapes may have to depend on well-water, which could be a valuable commodity. Hauling water may not be efficient. Plants are left on their own to survive or perish.

Many homeowners will ration water to specific areas. Annual flowers and vegetable gardens tend to be the main recipients, though at times, this may seem wrong. Shouldn't you give your limited resources to something that is perennial, whether it's trees, shrubs or some perennial flowers? Trees and shrubs are more expensive and difficult to replace than a tomato plant or some petunias next year.

There are some things to do to minimize the stress on your plants, as well as limit your water use.

Mulch. Mulches keep moisture from evaporating into the air. They also keep the weeds down so less water is lost to another plant. Cooler soils are also a benefit.

Trees and shrubs should be mulched with 3 to 5 inches of organic material, such as wood chips or hardwood bark. Shallow mulches could be beneficial but usually will not control weeds as effectively; some water loss will occur.

Deeper mulches tend to restrict air movement and make it more difficult for rain to penetrate into the soil. The mulch itself will absorb some of the water before the roots do.

KEEP THE MULCH AWAY FROM THE TREE'S TRUNK. Leave an inch or two gap around the base of the trunk. Crown rots and animal injury may result if mulch is piled around the trunk of the tree.

Mulches should be something dry and partially decomposed. Wood chips, hardwood bark, leaf mold and compost are good. Grass clipping, once they're dried, are also O.K. If using sawdust, you may need to scatter some fertilizer on it to help prevent nitrogen loss in the soil.

Water in the early morning. Between 6 and 9 a.m. is ideal. You may lose more than 1/3 of the water to evaporation by turning the sprinkler on during the afternoon. Evening waterings may get the plant's foliage wet and increase the chances of diseases.

Water slowly. Allow water to soak in and not run off.

Soaker hoses are a good investment. It may take longer for the soil to get wet, but less water is lost to evaporation. You can also position the hoses around the plants and not worry about watering rows or aisles. Water where the plants are, but remember that roots often extend out.

Water at the dripline of trees and shrubs where the feeder roots are. Watering at the trunk of the tree serves little or no purpose.

"Gray water" can be used, with some discretion. Gray water is the water from washing machines, dishwashers, bathtubs, etc. As long as no harsh detergents or soaps were used in the water, it should be safe to use for plants. Some soaps specifically state that they are bio-degradable and can be used on plants. Toilet water should never be used.

Catch water from gutters into the rain barrel — an old-fashioned concept that's still worth something today. Use that water to supplement nature's.

David Robson is an Extension Educator, Horticulture, at the Springfield Extension Center, Cooperative Extension Service, University of Illinois. You can write to Robson in care of Illinois Country Living, P.O. Box 3787, Springfield, IL 62708. Telephone: 217-782-6515. E-Mail: robsond@idea. ag.uiuc.edu

16 ILLINOIS COUNTRY LIVING • JULY 1996