unit educator, horticulture, University of Illinois
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[June 29, 2012]
It's that time of year again --
90-degree-plus temperatures accompanied by the snap, crackle, pop of
grass under your feet. If you think we get parched in the heat, how
do you think plants feel?
Signs of a thirsty plant are wilting leaves followed by
loss of leaves (the same signs apply to overwatered plants).
Most plants will benefit from 1 inch of water per week to
maintain plant growth.
During the summer months, watering lawns and landscape plants
can account for 40 percent of a typical household's water
consumption. Using water wisely in the landscape begins with the
landscape plan and plant selection, followed by good soil
The key to developing a landscape plan begins with knowing
the sunlight and soil conditions of your yard, and whether
drainage is good or bad. Select plants that are suitable for the
site and with low water needs, such as native plant species.
Group plants with the same watering needs into the same planting
beds. This will prevent overwatering of some plants and
underwatering of other plants. Prior to planting, work the soil
deeply, and if needed, add amendments to loosen. Composted yard
waste or mushroom compost make good soil amendments. A
well-drained, loose soil will allow plant roots to spread deeper
in the soil to obtain water and nutrients.
Some more watering tips include:
Water early in the morning, before 8 a.m., or in the evening,
after 6 p.m., and avoid watering on windy days. As much as 30
percent of water can be lost to evaporation by watering during
the hottest part of the day. Watering in the evening can
increase disease problems.
Most plants, including your lawn, prefer 1 inch of water per
week. Depending on the soil type, 1 inch of water will wet the
top 6 to 8 inches of soil. The frequency and amount of water
applied is determined by weather conditions and soil
A slow, thorough, deep watering is better than several light
sprinklings. Deep watering encourages deeper root growth, which
helps plants survive drier conditions. Lawn sprinklers, soaker
hoses or drip irrigation add water to the ground slowly. Soaker
hoses and drip irrigation systems are generally more efficient
and cause fewer disease problems than sprinklers. Hand watering
generally does not penetrate beyond the top 1 inch of soil;
thus, you waste water and time.
Watering newly planted trees and shrubs should be your top
priority. Flowers are easier to replace than a tree. Don't just
water at the tree trunk; soak the entire area beneath the tree
canopy because that is where the roots are growing.
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Cool season turfgrasses, such as Kentucky bluegrass, can
survive extended periods of drought by going dormant. Leaves
will become brown, but roots and crowns remain alive for four to
six weeks. If you do water your lawn, the best time to start is
at the first sign of water stress: when footprints remain in the
turf instead of leaf blades bouncing back. Once you have started
watering your lawn, you must continue to do so.
To help conserve water use on lawns, mow higher, avoid traffic over
the lawn, avoid pesticide use on drought-stressed lawns and do not
remove more than one-third of the leaf blade at any one mowing. In
the hottest, driest weeks, that means letting the grass get 3 1/2
inches tall before you mow.
Ground covers require less water than turfgrass. Consider
replacing some of your lawn with ground cover.
Use organic mulches around your plants. Shredded hardwood bark,
wood chips, composted shredded leaves and compost will conserve soil
moisture, improve soil structure and moderate soil temperature.
Mulch should be 2 to 4 inches deep and kept away from plant stems.
Reduce competition and stress to plants by keeping weeds, insects
and diseases under control. Stress and competition increase the
water demands of a plant.
For more tips on reducing water usage inside and outside the
home, visit American Water Works Association at
University of Illinois Extension]