Despite the Wet Spring, Don’t Forget To Water

I am sure you would agree that Mother Nature has been dealing us some foul weather in the last 12 or so months. First there was the late spring freeze in 2007, then there was the drought in the summer of 2007 and according to Pat Guinan, the Missouri State Climatologist, “preliminary numbers indicate that for Climate Division 6 (the Missouri Bootheel), the period January thru May 2008 ranks as the 10^th wettest on record since recording began in 1895”. Don’t take for granted how much stress all these weather extremes can put on your plants.

Well established trees, shrubs and landscape plants can usually withstand a year of drought conditions and abuse by what the plant considers too little water. That type of care does cause stress. Stress can reveal itself up to three years later as early leave drop, dead limbs after the spring flush or an overall appearance of drooping. Heat stress in lawns is more immediate, appearing as purple-blue wilting leaves, noticed most easily by purple tinged areas, or footprints that do not disappear when you walk through your yard. At this point it is not too late to water and save lawns from hot, dry conditions. Signs further develop as lawns go dormant. This dormancy may become permanent death if grasses do not receive water for an extended period of time, as can occur during drought. Gardens can suffer from the heat and wind as observed by wilting, droopy leaves and finally death of actively growing stems and leaves. A garden can look great one day and, after a windy, dry day look extremely neglected. Decorative pots can be the hardest hit and may only be able to withstand a day without water during very hot and windy conditions.

Proper watering begins with a good forward thinking plan. Each area can be treated separately as they have different water requirements. Remember that the first defense against heat and drought is to have a healthy root system and healthy plants.

Grass should be kept as tall as possible for the species and mowed with a properly sharpened blade to produce a dense cover with a deep root system. A deeper root system draws moisture from a larger volume of soil and results in less need for irrigation. Grass height should never be less than 2-1/2 inches after mowing and clippings should be around 1 to 1-1/2 inches long. A lawn mowed at heights of 3 to 3-1/2 inches will have a better chance of surviving prolonged drought and water restrictions. Apply nitrogen fertilizer to cool-season grasses (Kentucky bluegrass, tall fescue and perennial ryegrass) primarily in the fall.

When signs of heat stress appear in your lawn it indicates the need for a thorough watering if grasses are to remain green and actively growing. The best time to water a lawn is from 6 to 8 a.m. During this time the water pressure is highest, disruption of the water pattern from wind is low, and water lost to the atmosphere by evaporation is negligible. Watering early in the morning also has the advantage of reducing the chance of turf diseases that require extended periods of leaf moisture. Avoid irrigation during mid-day and windy conditions.

A newly seeded or sodded lawn should be watered daily and may need as many as four light applications in a single day for seed and up to two times a day for sod. Keep seedbeds moist, but not saturated, to a depth of 1 to 2 inches until germination occurs. Keep sod strips wet as well as the top inch of soil below the sod. Apply straw (one bail per 1,000 square feet) at the time of seeding to help shade the ground and prevent rapid drying of the soil surface. As seedlings reach 2 inches in height, gradually reduce the frequency of watering and water more deeply. As sod becomes established and roots penetrate and grow in the soil, gradually reduce the frequency of watering but wet the soil deeper.

Approximate lawn water requirements are as follows: Perennial ryegrass - 1.5 inches of water per week for green turf and 1.0 inches of water per week for dormant turf. Kentucky bluegrass - 1.2 inches of water per week for green turf and 0.7 inches of water per week for dormant turf. Tall fescue - 0.8 inches of water per week for green turf and 0.5 inches of water per week for dormant turf. Zoysia or Bermuda - 0.5 inches of water per week for green turf and 0.2 inches of water per week for dormant turf. Buffalograss - 0.3 inches of water per week for green turf and 0.2 inches of water per week

A good rule of thumb for trees is to saturate at least 20 percent of the root zone of the plant at least one foot deep. This can be done by rotating your irrigation around the tree base each time you water. Test the depth of water in soil by pushing a steel rod into the ground. The rod will be difficult to move when it hits dry soil. Usually two or three irrigations during an extended drought will greatly reduce drought stress of trees and keep established plants in good condition. Newly planted trees should be watered every few days with a gallon or two of water until they can grow roots out into the soil, this may take a season. Irrigate established landscape beds at least once every two weeks during hot, dry periods. A sandy soil will require more frequent irrigation with smaller quantities of water.

When gauging the water requirements for a garden use the simple rule, when the plants are dry, water thoroughly. One of the worst mistakes people make in their gardens is trying to 'sprinkle' them each day by using their thumb and the end of a running hose. Most gardeners just don’t have the patience to stand in one spot long enough for deep water penetration. Most plants should be watered in the morning. Watering in the evening increases the likelihood of disease invasion, as the majority of diseases develop most rapidly in cool, moist conditions. Avoid hard, high pressure streams of water as these can affect the fruit set and blooms on your garden plants. If you have automatic sprinklers in your garden water smaller areas at a time with low pressure and even drop placement. The best automatic irrigation would be trickle or drip as this will keep water off your leaves and prevent evaporation by wind.

Decorative pots should be repotted if the plant roots become too big for the pot or if roots are plugging the drainage holes. Roots should be white in color and have plenty of space to grow and room for oxygen to penetrate. A good mix of organic matter in your potting media helps with nutrition as well as a slow release fertilizer applied each spring. Generally, the larger the container, the less attention will be required to care for the plants. Decorative pots can be watered by hand each day or by trickle irrigation directly in the pot. Regardless of the method you may need to water twice each day for some plants during normal weather and for all plants when it remains dry and windy. Make sure to check plants daily even if you use trickle irrigation as lines can become dislodged or stopped up, causing plants to go without water. Because the soil in hanging baskets dries faster than the soil in the garden or in larger containers, more frequent watering is necessary. Ideally, hanging baskets and other containers should never dry enough for the root mass to pull away from the sides of the container. When this occurs, containers should be set in a pan of fairly deep water to allow the mass to rewet and expand. Thorough soaking may take 15 to 30 minutes.

There are not enough good things that can be said about properly mulching your plants. It can be used around trees, landscape plants and in the garden. It keeps the soil cool, conserves moisture and provides a more favorable environment for root growth. Mulch also reduces mower damage and eliminates competition from grass roots. A three inch thick layer of bark mulch is sufficient for trees and landscape beds. In the garden you might try composted leaves, straw or peat moss.

Helpful Information: Check your gardens for aphids, cucumber beetle, squash bugs and mites. They are out and about.

Helpful Publication: Missouri Environment and Garden, College of Agriculture, Food, and Natural Resources, News for Missouri's Gardens, Yards, and Resources, May 9, 1996. Vol. 2, No. 4; MU Guide Sheet G6720, Home Lawn Watering Guide.

The Extension office is located in Kennett, Missouri at 101 South Main Street (the old bank) on the 2^nd floor. Open Monday – Friday or you can call 573-888-4722 if you have a question. University of Missouri Extension programs are open to all.

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Sarah Denkler, Horticulture Educator
University of Missouri Extension
P.O. Box 160, Kennett, MO 63857
573-888-4722 Denklers@missouri.edu