EECO Farm Gardening Central
Links and information for Organic Gardeners
Keeping Water Where It Belongs — Peter Garnham
When you want a drink of water, you can walk over to the faucet or grab a bottle. Plants don’t have that option - they depend on the water you give them, or what falls as rain. How much water do plants need, and what’s the best way to get it to them?
A general rule of thumb is one inch of water per week. Plants that get an inch a week will certainly survive, and will probably thrive . . . unless it is blazing hot, unless the soil was dry as a bone to start with, and unless the soil is very sandy, so use your judgment.
• In extremely hot weather, soil dries out fast and may stress your plants.
• If the soil was allowed to dry out, an inch of water will hardly reach plant roots, and may just run off on the baked surface of the soil.
• Very sandy soil can’t hold water, so it just sinks down below where roots can reach.
So what’s a gardener to do for thirsty plants? First, get a rain gauge. This is a cheap (about $5) plastic funnel-shaped container with marked inch gradations down the side. Mount it in your garden attached to a stake. Don’t allow anything to get between it and the sky (such as a giant sunflower). When it rains, water collects in the gauge, and you can read how many inches of rain - or what fraction of an inch - fell. Now you know whether your plants need a light watering or a thorough soaking.
Next, work a lot of compost into your soil. Compost helps hold water where plants can reach it. Compost-enriched soil takes longer to dry out, even in hot weather. It also feeds nutrients to your plants, and helps to prevent diseases.
Lastly, but most important, get a drip irrigation system. Plants need water around their roots, but water on their leaves is harmful and can cause diseases. Overhead watering systems, such as sprinklers, waste a lot of water - about 70 percent of sprinkler water is lost to evaporation and never reaches the plant roots.
If you want to get fancy, you can buy a soil moisture meter. Alternatively, you can learn to do what experienced gardeners do - stick your finger down into the soil to see if it is damp below the surface. Damp soil feels cool. If you want to protect your fingernails, use a small trowel to see whether the soil an inch or two under the surface is damp.
With a rain gauge, it is easy to see how much water fell on your garden. Figuring out “an inch of water” with an irrigation system involves a calculation of gallons per hour, drip rate, and the area to be watered. But as a rule of thumb, with the drip irrigation systems EECO Farm made available to gardeners in 2004, it takes two or three hours to deliver an inch of water.
Peter Garnham is an Enterprise Farmer at EECO Farm, growing a variety of culinary herbs, and a Cornell Cooperative Extension Master Gardener. He lives in Amagansett.
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