Archive for Sunday, July 15, 2012

Garden Calendar: Help out lawns, landscapes during severe drought

July 15, 2012


You might have trouble hearing them over the hum of the air conditioner, but your trees are out there crying for water. They need your help, and a little tender loving care now can save you a lot of money later.

I have already seen a fair number of dead river birch and red maple trees whose problems likely started last year. Other tree species are showing stress and are more susceptible to insect and disease pests that will only compound the problem.

In some yards, it appears as though fall has already arrived! When trees lose their leaves, they lose the ability to photosynthesize and store energy that is necessary to get them through the rest of the year.

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Shrubs, flowers, and fruit and vegetable plants are also showing stress from the high temperatures and drought. In addition to leaf drop, typical symptoms include yellowing, browning and scorching of leaves and stems.

The rain received in some parts of the county last week helped but was not enough in most cases to alleviate the drought conditions we were already experiencing.

Irrigation systems also help but may not be enough for ornamental plants, depending on specific site conditions.

The most important words to remember when it comes to watering are deep and infrequent. Watering deeply means applying enough water that it can soak into the soil profile rather than just wetting the soil surface. Watering infrequently means allowing soil to dry between applications of water.

Deep and infrequent watering develops strong root systems that can better support plants during periods of moisture stress like the drought we are currently experiencing.

To determine if your plants need water, first check the soil moisture. A long screwdriver or something similar works well in place of a soil probe — just try to push the screwdriver into the ground to a depth of 6 inches to 8 inches. When the soil is dry, the screwdriver will likely be very difficult to push into the ground. This method is somewhat dependent on soil type, but you can get a feel for it by trying it occasionally under different climatic conditions.

If the soil is dry when you check it, apply water deeply and infrequently. Soaker hoses, drip irrigation, deep water wands that apply water below the soil surface, leaky buckets and watering bags are good choices to reduce water loss from wind and evaporation. Watering early in the morning is best for plant health.

For trees and shrubs, I like to turn the water on really low pressure and let it run out over the root zone for a few hours at a time in order to water deeply. I keep a watchful eye on the hose to make sure excess water is not running off the area and again use the screwdriver/probe method to check soil moisture below the surface.

Someone once told me that a good way to visualize the root system of a mature tree was picture a wine glass sitting on a turkey platter — with the glass representing the tree and the platter representing the root system.

When watering trees, apply water over as much of the tree’s root system as possible for best results.

Check the soil moisture again in 5-7 days and continue watering deeply and infrequently as needed. Unless the soil is dry every day below the surface, there is no need to water every day! Too frequent irrigation results in inadequate root systems.

For lawns, it is also important to understand the difference between dead and dormant. Allowing a lawn to go dormant in summer is great, but the grass can completely die in drought conditions like what we are experiencing.

Check some of the individual grass plants for green at the soil surface, and water at least once every few weeks just to keep the grass alive. If the grass is dead now, make plans to re-seed in September.

And as much as I dislike thinking about the cost of water, I know it is less than the cost of removal and replacement of any of these plants.

According to the United States Drought Monitor, current conditions in Lawrence and Douglas County are classified as severe drought.

— Jennifer Smith is the Horticulture Extension Agent for K-State Research and Extension in Douglas County. Contact her or an Extension Master Gardener with your gardening questions at 843-7058 or


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