Beat the Heat: Conservation-Based Garden Watering Systems
In a perfect growing season, an inch of gentle rain falls each week. Gardeners dream of such a season, but native plants know better than to expect perfect weather. In response to dry conditions, they close their stomata (the thousands of “breathing” pores on both sides of their leaves) to limit moisture loss, and send roots deeper in search of water.
Although many native plants possess these admirable talents, most food-garden plants are, by comparison, amateurs at adapting to your local rainfall patterns; they need help. Delivering water wisely means minimizing wasted water and wasted time. In more practical terms, it means anticipating your garden’s needs and setting priorities, having a conservation-based garden watering system in place, preserving water through mulching, and finding innovative ways to work out the kinks in your garden’s water supply.
Which Ones Want the Water?
When figuring out your watering priorities, start with newly planted seeds, transplants of any kind and plants grown in containers. All of these almost always need supplemental water, which is usually best done with hoses and watering cans. To help maintain continuous surface moisture in newly seeded beds, cover them with burlap blankets or thrift store curtains on sunny days until the seeds start to sprout.
The next-priority plants are crops that can suffer permanent damage due to inconsistent soil moisture. Lettuce and other salad crops lose their flavor when the soil gets warm and dry, and tomatoes often split when dry conditions give way to a soaking rain. Mulches are the easiest way to avoid fluctuating soil-moisture levels when growing these and other sensitive plants. Biodegradable mulches (such as leaves, compost or clean grass clippings) block surface evaporation while suppressing weeds and making important contributions to the soil’s supply of organic matter. You can even double-mulch by covering a sheet-type mulch (of newspaper or cardboard) with grass clippings or another biodegradable mulch.
Different Soils Need Different Techniques
Although mulching will help even out soil moisture levels, unless your climate gets the absolute ideal amount of precipitation, you will be watering your garden plants. When doing so, your goal is to simulate drenching rain that replenishes moisture throughout plants’ root zones. When and how you water should be tailored to your soil’s natural tendencies. For example, water percolates slowly through tight clay soil, so a slow, deep soaking once a week works well. Sandy soil has plenty of open spaces that help water move downward quickly, so concentrated drenches twice a week are a better strategy. Site is a factor, too: High, sunny spots always dry out faster than low, shady ones.
The most efficient way to provide consistent moisture to garden plants is with soaker hoses (porous hoses that slowly weep water into the soil) or drip lines (which emit water in tiny trickles). Both distribute water exactly where it’s supposed to go, with little or no waste. You can put a simple system together as you plant your garden, and change the location of the soaker hoses or drip lines as crops come and go. For maximum versatility, limit the length of soaker or drip hoses to less than 50 feet, and install pop-in connectors to the female ends of each hose.
To supply water to plants outside your drip lines or soaker hose network, punch a few small holes into the sides of milk jugs or kitty-litter jugs an inch from the bottom, fill them with water, and let them drip into the root zones of thirsty plants. The water that remains in the bottom of the jugs, below the holes, will keep them from blowing away.
Sprinklers are fun, but they lose up to half their water to evaporation and runoff. Occasionally there are good reasons to use a sprinkler: If dry weather hits as tomatoes are in full bloom, a late afternoon sprinkling will increase overnight humidity levels and enhance pollination by making it easier for pollen grains to fuse with waiting ovaries. Sprinklers also are great for providing moisture for seeds planted in broad blocks, such as a cover crop of buckwheat. Watering by hand is more efficient, but doing it right eats up hours of time.
Rain Water Harvesting
If you’re looking to reduce supplemental water use in your garden, make the best use of the rain that falls on it for free. Of course, you can buy or create a rain barrel to collect rain from your roof (read more about it in Conserve Water by Harvesting Rainwater: How to Make a Rain Barrel), but harvesting rain for garden use can begin in the garden. Use a hoe to create shallow furrows along planted rows to detain rain that would otherwise flow into paths. In similar fashion, you can make raised rims around beds to create a basin effect. Should you get too much rain, one decisive swipe with a hoe or spade will open the earthen floodgates.
You also can collect rain in containers stationed near the garden. Last summer when my neighbors downsized their herd of cows, I was the lucky recipient of a 50-gallon stock tank, which partially refills itself with each shower. The sun-warmed water is great for rinsing dirty hands or washing pots, or for dipping out to pour on parched plants. Maintenance is limited to adding mosquito-killing Bt (Bacillus thuringiensis, an organic pesticide) doughnuts to the water. If you’re a serious water conservationist, you might also consider setting up a graywater system, which uses slightly dirty water from showers, tubs and washing machines to irrigate plants. Learn more about them in Pipe Dreams: The Basics of Graywater Systems.
Use Water-Smart Hardware
• Good watering hardware can save hours of time—and hundreds of gallons of water—in the course of a growing season.
• Outfit outdoor faucets with splitters so you can attach two hoses to each one.
• When using a sprinkler, soaker or drip system, use a timer so you won’t have to remember to turn the water off.
• Buy high-quality hoses that are not prone to kinking. If you keep numerous containers on your deck or patio, consider getting a springy coil hose that can be stashed in a corner between uses.
• Replace washers as needed to make sure hoses and faucets connect tightly.
• Keep a supply of couplers on hand to repair cracks and leaks in hoses, or to splice together pieces of soaker hose.
Build the Best Beds & Paths
Every garden will benefit from using permanent beds and paths rather than tilling the entire garden every year. Permanent beds allow you to concentrate water and fertilizers where they are needed and keep paths drier and mulched to prevent weeds. Perhaps most importantly, by never walking on the beds you avoid compacting the soil. Use dense planting in beds as a hedge against water loss in dry weather—a good cover of leaves shading the soil cuts surface evaporation by more than half.
If you live in a climate with very high rainfall or dense clay soil, use raised beds to improve soil drainage. Drainage is critical for most food crops—roots in waterlogged soil are deprived of oxygen. Raised beds also allow soil to warm up earlier in spring.
Live where rain seldom falls? Make use of sunken beds. This ancient Zuni Indian method is sometimes known as waffle gardening. By planting in slightly recessed beds, when rain does fall, it will flow toward the plants’ roots. Between rains, young plants will be protected from drying winds.
Contributing editor Barbara Pleasant gardens in southwest Virginia, where she grows vegetables, herbs, fruits, flowers and a few lucky chickens. Contact Barbara by visiting her website or finding her on Google+.
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