One last factor: How should you apply water? Drip irrigation? A sprinkler? Your choice affects how much water you need to put on the garden. Drip irrigation is more efficient—about 85 percent of the water goes directly to the plants' root zone; overhead watering is about 70 percent efficient. Be sure to add more water to compensate for these inefficiencies. And no matter how you apply the water, remember to water slowly to minimize runoff.
Other Water-Wise Tips
Conserving water can be just as important as adding water to your garden especially during dry spells. Here are some hints to help ensure your garden loses as little water as possible.
Mulch, mulch, and mulch some more.
Mulching can save almost one-third of the water you put on your garden, according to researchers. Mulch will also help keep soil cooler and protect tender roots. And it will keep down your biggest competitor for garden moisture—weeds.
Apply up to 3 inches of compost, wood chips, grass clippings, or any other organic mulch. (If you mulch on top of a drip-irrigation system, you may have to cut back on the amount of water you apply because mulch makes drip irrigation superefficient.) Just don't use plastic mulch with overhead sprinklers—the water won't get through to the soil.
Plan ahead to conserve water.
First, try to do as much of your planting as early as possible in the spring and late in the fall. In these cooler times of year, a minimal amount of water is needed to get plants going strong (and strong plants are better able to tolerate droughts later on). Be aware, however, that cool-season crops generally have shallow root systems and require more frequent watering.
Garden in raised beds.
The deeply loosened soil in a raised bed absorbs water better than the soil in a standard garden will.
Space plants closely.
Reducing spaces between plants in beds and between rows will make mature plants into a living mulch—much of the soil will be shaded by their leaves.
Group crops that have similar water needs.
Plant your heavy water users, such as beets and broccoli at one end of the garden, light users like beans and squash at the other. Then water the two areas separately.
Cut down on cultivation.
Working your soil quickly dries out the upper few inches. Instead of hoeing to keep down weeds, smother them with moisture-conserving mulch.
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