David Robson Extension Educator, Springfield Extension Center, University of Illinois
Yard & Garden
Watering that works
How to give your plants a proper drink of water
Right now, we could be in the midst of a drought, or keeping our waders by the backdoor. The past two years have been more than kind in their amounts of rainfall, to the point that we sometimes wished someone would turn off the sky faucet.
On the other hand, rain is great for most garden plants, and even more fantastic for the wallet. Not having to pay for water is one of a gardener’s little life pleasures.
But forecasters are essentially higher class fortune tellers, who can determine with relative foresight what the weather conditions will be for the next day or two, but have a harder time delivering what will occur over the next several weeks or months.
That means it’s up to us to be prepared as Boy Scouts to keep our plants actively growing if and when Mother Nature decides to plug the clouds.
So, let’s look at a few facts about watering plants, including which ones to water.
First, if push comes to shove with time, energy and water availability, forego the lawn. It sucks up water faster than a sponge and then wants more. If we’re lucky, the lawn will go dormant and stay that way until cooler temperatures and more rainfall shows up in September and October.
If not, and the lawn does die, it can be replaced with seed or sod. Within six weeks, you’d have a hard time knowing that it was gone.
That’s not to say that lawns aren’t important. But in the grand scheme of it all, mature trees and shrubs are much more important. They can’t be replaced that quickly. As the foundation to your landscape, it’s more important to keep them actively growing.
I’ll go out on a limb and say that the trees and shrubs are even more important than your vegetable garden if you have one. While we like to think our tomatoes and peppers are valuable, they really don’t have much monetary value. On the other hand, they are worth more than the lawn and our annual flowers.
To water most plants properly, you need to provide them with an inch of water when plants are growing and the temperatures are less than 85-90 degrees. Over that temperature, you may need to double the amount of water.
The point of the inch of water is to penetrate the ground at least 8 to 12 inches. While you may not have many roots down that deep, you want to drive them deeper. That way, they stay cooler, and develop a more extensive root system in search of water.
Next, if you have to water, water so that it actually benefits the plant.
So many folks think that turning the sprinkler on for 20 minutes is good enough. It’s not. You need to keep the water flowing through a sprinkler for at least 90 to 120 minutes to supply that inch of water.
Wetting just the top few inches keeps the roots up close, where they are exposed to the warmer temperatures that dry out the soil. In other words, the plant will wilt faster and more often.
Trickle and drip irrigation hoses are a little more difficult to figure out. While you can turn them on and walk away, it’s harder to gauge when they’ve wet the soil 8 to 12 inches deep. Typically, and it’s not a guarantee, you may have to leave them on for at least 6 to 8 hours. However, some ooze water faster while others are just the opposite. Your best bet is to start with four hours, and then see how deep the soil is wet beneath the hose by insert a trowel or steel rod.
The advantage with slow irrigations is the fact that you can water by the plants, and not in the areas where there isn’t any growth. However, you may not be forcing roots to spread out, especially if you place the irrigation hose right next to the plant.
Don’t water any faster than the soil can absorb the water. It’s terrible to watch all the water pool around plants, or even worse, to run down the hill taking some of your soil with it. You may have to adjust your water pressure from your faucet or choose another type of sprinkler.
And finally, don’t forget to mulch. It’s always the best way to cut down on water loss. Two to four inches is ideal for just about all plants.
David Robson is an Extension Educator, Horticulture, at the Springfield Extension Center, University of Illinois Extension, P.O. Box 8199, Springfield, IL 62791. Telephone: 217-782-6515.
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