Smarter Living: Yard & Garden
Garden Better With Less Water
It takes nearly sixteen gallons of water to grow just one head of lettuce, 18.5 for an apple. Multiply those numbers by the abundance of fresh food growing in a typical backyard garden, and it’s easy to imagine why over 40 percent of freshwater used in the United States goes into growing food.
Photo: Hint of Plu/Flickr
Fortunately, when you live in a wet climate, the majority of a crop’s water needs—and then some—are met with rainfall. But even in the Pacific Northwest, when the summer sun finally sets in, weeks can pass back-to-back without a drop. To keep your garden sufficiently moist, the three vegetable beds, multiple pots and occasional inedible plants and flowers growing around the yard require between twenty and twenty-five gallons of water every two days during a heat wave—or as much as 375 gallons in a month with no rain.
Here’s how to keep your vegetables growing without draining the water supply:
Step 1: Water in the morning or in the evening.
This limits evaporation from the hot sun and water loss, allowing the moisture to penetrate deeper, and avoid watering when it’s windy, which carries moisture away from where you apply it and where it’s needed.
Step 2: Mulch! ...to slow moisture evaporation.
Apply a layer of organic material, such as bark, grass clippings, or hay, on top of the soil around the base of plants and trees. The material slows moisture evaporation, while suppressing weed growth and adding beneficial nutrients to the soil as it breaks down.
Step 3: Retire the sprinkler.
Even when positioned properly (so that the water arch falls mostly on the garden and not on the sidewalk, the house, or the barbecue) sprinklers are inefficient, jetting water into the air where sizable fractions are lost to evaporation and impermeable surfaces. On a hot or windy day, the percentage of water that lands where it’s needed is reduced even more. Instead water by hand or lay soaker hoses. Remember when using a watering can or a hose use a variable spray nozzle to ensure targeted streams and minimize water loss.
Step 4: Lay down soaker hoses in garden beds.
Soaker hoses release water through the sides and, when laid in the garden, directly into the soil where moisture is needed. To maximize efficiency, lay them down on level ground an inch or two away from plant bases. Connect them to the faucet with a regular garden hose to keep water from seeping out where it’s not needed. Cover soaker hoses with mulch to retain moisture and always locate the hose before digging or weeding with sharp tools.
Remember to check for leaks in watering equipment. Run through your watering hardware (hoses, faucets, etc.) periodically to check for leaks. A single leaky spigot dripping at a rate of one drop per second can waste more than 3,000 gallons of water per year.
Step 5: Install rain barrels and rain catchers.
Rain barrels are connected to the home’s downspout and collect rain as it runs off the roof. Most can hold about 50 gallons and will fill to the brim with just half an inch of rain. Because rooftops can collect bacteria as well as water and because some roofing materials contain hazardous chemicals like heavy metals, it is generally recommended to avoid watering edible plants with water from a rain barrel. Use it instead to water flowers, shrubs and lawns, and use a rain catcher for the rest. Rain catchers are free-standing containers that collect water directly from the sky, rather than from a dripping surface. Hoses can be connected directly to rain barrels and catchers, or watering cans can be filled from the spigot.
Choose systems with debris screens and keep the container tightly covered to prevent mosquitoes from breeding. Before the first winter frost, disconnect rain barrels from the downspout and wash out and empty containers. Store the container upside down until the last frost has passed. The more containers you have, the more water is collected and the farther your stored water will take you through a dry spell.
Enjoy your vegetables!
Growing your own allows you to see first-hand the resources that go into producing each leaf of lettuce and each broccoli head—not the least of which being your precious time and energy. Harvesting plants as they mature frees up water and nutrients for younger plants that need those resources to grow, and many vegetables, like leafy greens, are especially yummy when young. So pick early and pick often.
last revised 4/26/2011