This gardening season, with climate change causing higher temperatures and desperate droughts in multiple regions, many of us will experience weeks or even months in which sparse rainfall won’t keep pace with the sun’s hot rays. To keep your crops’ thirst quenched, try some options outlined in this roundup of water-wise gardening strategies, from familiar garden watering systems — such as soaker and drip hoses — to a lesser-known system called “partial root-zone drying.”
The best watering methods will depend at least partly on planting arrangement and crop type. Planting leafy greens, onions and other shallow-rooted plants in blocks rather than rows will simplify watering, especially if you water by hand. With crops that occupy more time and space in the garden, such as beans, peppers, sweet corn and tomatoes, better options include using soaker hoses, drip irrigation or carefully managed ditches. Even with regular rainfall, crops that require a relatively large amount of water to thrive, such as beans and sweet corn, will almost always need supplemental irrigation.
Weeding and Mulching Boost Watering Efficiency
A water-wise garden is no place for weeds. According to research from Michigan State University, a combo of good weed control and adequate mulch can conserve up to 1 inch of water per week during toasty summer months. Left uncontrolled, however, some weeds, such as crab grass and lamb’s-quarters, will slurp up more than 80 gallons of water to produce just 1 pound of plant tissue.
Fundamental organic gardening practices that improve soil and limit weeds will set the stage for efficient garden-watering systems. If you add compost or rotted manure to the soil each time you plant, as well as use biodegradable mulches that break down into organic matter, your soil will retain moisture better. In general, the more grass clippings, leaves, coffee grounds and other organic materials you add to your soil, the less likely your crops will be to suffer from moisture stress. Another reason to be mad for mulch: Even before it breaks down into organic matter, a thick layer of mulch applied around plants will help by cooling and shading the soil, thus keeping your garden from drying out quickly after a watering or rain shower.
Soaker Hoses and Drip Irrigation Systems
I have long been an advocate of the 25-foot soaker hose, which weeps water evenly along its length, as if it were sweating. Soaker hoses work especially well for closely spaced crops and intensively planted beds. You can make your own soaker hoses by collecting old or leaky garden hoses from your friends and drilling small holes into them every few inches. Just cap or clamp off the male end of the hose.
Drip irrigation systems distribute water at regular intervals through a network of hoses or tapes with slits, pores, emitters or drippers. They work well for rows of crops spaced at varying intervals (you can set the emitters at wider spacing if you’re watering a crop planted farther apart), and perform best on relatively level ground, because pressure changes caused by sloping ground would result in uneven watering. If you have a large garden, look for systems that use inexpensive drip tape (brands include Aqua-Traxx, Chapin and T-Tape). The tiny holes in some emitters and drippers can become clogged with soil particles rather easily, so at least one filter needs to be screwed into the water line between the faucet (or reservoir) and the distribution lines of most drip irrigation systems.
Typical soaker hoses require at least the level of pressure from a faucet, but some drip emitter systems can use gravity alone to gradually distribute water from high cisterns or raised rain barrels to thirsty plants. For example, growers at New Mexico State University had great success raising 50-gallon water barrels head-high on a frame or platform and attaching several drip lines that fed out to a large garden plot.
To achieve deep watering from soaker hoses or drip systems, let the water run for several hours, turn off the water for an hour or so to allow the moisture to penetrate, and then water some more. Especially in clay soil, water from soaker hoses or drip irrigation can be slow to move to the subsoil, so these systems are best used often so the soil never dries out. I recommend using a timer to keep track of when to turn your soaker hoses on and off. Another memory aid: Put a rubber band around your wrist. If you’re getting ready for bed and you find the rubber band still there, it means you forgot to turn off the water.
While drip systems work well for crops planted in rows, crops grown in wide beds may do better when planted around a buried reservoir designed to deliver water to the plants’ root zones, about 4 to 8 inches below the soil’s surface for many crops. Plus, gravity-fed systems and buried reservoirs would free you of any worries about whether you remembered to turn the water off. One ancient technique is to bury porous terra cotta jugs, called ollas, leaving just the mouths of the jugs aboveground. Fill them up, and they’ll then slowly seep water to plants’ roots. Handmade ollas aren’t widely available, but you can order them online at specialty stores like Dripping Springs Ollas and Growing Awareness Urban Farm.
After noticing that hard-shelled gourds often survive intact for more than a year in my compost pile, I plan to try using them as biodegradable ollas this summer. I’ll drill some tiny holes, cut off their necks, fish out the seeds, and — voilà! — gourd ollas!
Try the humble plastic milk jug or kitty litter container for more immediate olla alternatives. Fill jugs two-thirds full of water and freeze them. When frozen solid, take them outside and make lots of little holes in them using a drill or nail, covering all sides with holes up to the jugs’ shoulders. (Freezing first will keep the sides stable for easy drilling.) Bury your jugs in early spring, before you plant crops. Place such reservoirs where a tipi of beans will go, or in the center of where you’ll plant a trio of peppers, filling them as needed.
If you have some black plastic nursery pots, you can turn these into water reservoirs, too. Line the bottoms with a double layer of newspaper, fill the pots with small rocks or stones, and then sink them into the soil up to their rims and fill with water as needed.
Simple Irrigation Ditches
In extreme summer climates, where plants are screaming for water at the end of hot days with drying winds, old-fashioned irrigation ditches are quite practical when closely monitored. Your garden should be relatively level and laid out in rows for ditches to work efficiently. When crops are still small and you’re hoeing to control weeds, cut shallow trenches along at least one side of each row. Then, when plants need to wet their whistles, simply drop the hose in one end of the ditch, continue with other chores for a bit, and then remove the hose after the ditch has filled.
MOTHER’s Editor-in-Chief, Cheryl Long, likes to use irrigation ditches for most of her crops. “I choose soaker hoses for my perennials, such as strawberries and asparagus, but for annuals, I find it’s easier to use a hoe to shape irrigation ditches right after planting,” she says. This method won’t require any extra equipment, and it will direct water to plants’ root zones and keep you from watering paths and other unintended areas.
What About Watering with Sprinklers?
Popular and affordable, sprinklers will save time when you need to keep newly planted seed beds constantly moist, and periodic use of sprinklers can help dissolve salts that accumulate at the soil’s surface in some regions. Overhead irrigation via sprinklers may also be a good option if you have a large planting of crops with wide root zones, such as winter squash, the roots of which can reach up to 25 feet in diameter in just 11 weeks.
The main downside to sprinklers is that they can be wasteful — they water walkways and other unplanted areas, and a significant amount of water is lost to evaporation and wind. Plus, especially in humid conditions, leaves dampened by sprinklers may stay moist and become a hotbed for diseases. Watering sweet corn, staked tomatoes and other tall plants with a sprinkler can also prove challenging unless you elevate the sprinkler head to a height taller than the crops. In most situations, other garden-watering methods will be more efficient.
One way to store rainwater is to direct runoff from your roof out into your garden. Most soils can hold a great deal of water in the root zone, and roof runoff can help you keep your soil’s moisture levels high. We explain this approach in-depth in A Better Rainwater-Harvesting System. Many gardeners capture roof runoff in rain barrels for use in the garden. Routing stored water from barrel to garden will be easy if the rain barrel sits more than a foot higher than your garden, because gravity or siphon action will move the water effortlessly to your crops.
But what if your house is lower than your garden? The highest beds in my terraced hillside garden are more than 10 feet above the nearest rain barrel. A garden at a higher elevation than its water source is not a rare situation. At an off-grid organic farm near me, farmers use a solar pump to carry water from a spring to the highest part of the farm, where it’s stored in a tank or an aboveground cistern. From there, the water goes into gravity-fed drip irrigation lines — an elegantly simple system that can be replicated in a home garden by employing the kind of pump intended to move water in decorative fountains. On a sunny day, this type of inexpensive solar pump could easily be put to more practical use moving water uphill from your barrel to a waiting reservoir.
For an aboveground water-holding cistern, you can fill additional barrels, build a pond with a plastic liner, or find recycled, 275-gallon food-grade IBCs (Intermediate Bulk Containers), available online. A metal stock tank from a farm store would also fit the bill. Such a tank can perform multiple functions and will last for decades. In summer, the tank can be placed at the highest part of the garden as a water reservoir and produce-washing station. In spring and fall, use it for soaking shiitake mushroom logs, washing dogs, or other messy, wet tasks.
Sometimes, carrying water by hand is the only way to get it to where you need it, but water is heavy. Most watering cans hold 2 to 2-1/2 gallons, which will weigh about 20 pounds when full (water weighs about 8 pounds per gallon). When I must carry water, I prefer hefting two partially filled watering cans rather than one that’s brimming. I spill less this way, and this method is easier on my back. Better yet is to use a carrying pole, also called a “yoke,” that fits across your shoulders, making it possible to evenly balance two buckets using the strength of more body parts.
Sunken Beds and Planting Pits
In chronically dry climates with poor soils, such as the Southwestern United States and Western Africa, vegetable yields skyrocket when crops are grown in sunken beds that capture and retain scant supplies of rainwater. The Zuni Pueblo tribe of New Mexico has long sculpted its gardens into a series of 2- to 3-foot-wide squares, with the excavated soil piled into ridges around each square to create a waffle-like design. The ridges channel rain into the beds and provide a bit of shade and wind protection for the crops.
Popular in the small African country of Burkina Faso, the Zai pit method involves digging a series of holes — roughly 8 inches wide — and then refilling them partway with compost and manure. The excavated soil then gets piled into berms that shade and channel water to double rows of these permanent planting holes, which are refreshed with manure and compost each year. The Zai pit method at least tripled the productivity of millet in dry desert climates, and it has also worked miracles in the degraded soils of Ethiopia, increasing potato production five-fold, tripling the productivity of beans, and boosting overall water efficiency by 500 percent on average, according to a 2011 report published by Cambridge University Press.
Shade Covers and Windbreaks
In dire situations where hot sun and wind threaten to desiccate gardens, you can turn down the heat with shade covers or windbreaks placed alongside plants, or by planting shelter crops. For example, old window screens or pieces of lightweight cloth attached to stakes on the south side of your tomatoes can serve this purpose. In much of Texas, where drying winds necessitate water-wise gardening every season, green windbreaks of fall-planted grains, such as wheat, rye, sorghum or oats, shield winter onions and spring vegetables, and switchgrass, tall sunflowers or corn serve as shelter crops in summer. Ideally, the shelter crop will be well-established along the garden’s perimeter before regular garden crops go in.
Snow fencing makes a wonderful windbreak that’s easy to install by attaching it to metal stakes. Growers in hot, dry climates use this technique to shade the root zones of tomatoes and peppers while leaving the plants’ canopies open to the sun. Windbreaks can be quite small, too — place a wood shingle upright in the soil next to transplanted seedlings to block prevailing winds and harsh summer sun.
Partial Root-Zone Drying
In studies of the novel irrigation method known as “partial root-zone drying,” completed in 2009 at the University of Copenhagen, scientists grew tomatoes in partitioned pots so that only half the roots could be watered at a time. When half the roots were allowed to dry out, the plants launched defensive maneuvers. Leaf stomata remained partially closed to reduce moisture loss, and roots foraged more efficiently for nitrogen. Meanwhile, new growth and fruit development continued, because the plants’ watered sides received ample water and nutrients. Today, farmers are successfully using the partial root-zone drying irrigation method on corn, grapes, peppers, potatoes and other crops.
Here’s how to put it to work in your garden: Grow crop plants normally for the first six weeks, or until they are well-established. After that, employ soaker hoses, drip lines or irrigation trenches to provide water to one side of the plants at a time. When the plants need watering again, irrigate the opposite side. Partial root-zone drying will reduce yields slightly, but won’t affect fruit quality, and that small loss will be offset monetarily by saved water. When combined with soaker hoses or drip irrigation, the partial root-zone drying method will significantly improve watering efficiency.
Encourage Deep-Reaching Roots
Vegetable crops’ roots can reach surprising depths. This 10-week-old spinach plant and this nearly mature pepper plant have already hit 4 feet. Whichever watering systems you use, as your crops begin to mature, water deeply and less frequently so roots grow strong and reach down farther, rather than watering often but shallowly.
When a drought has you in its grip, you desperately want to know when it will end. Here are some tools to help you find out when it will be right as rain again.
U.S. Drought Portal: One of the best drought-monitoring tools available. Searchable by ZIP code, and includes early drought warnings.
U.S. Drought Monitor: Hosted by the University of Nebraska in collaboration with several federal agencies. Updated weekly with a written summary and reports from nine geographical regions.
Climate Prediction Center: Hosted by the National Weather Service, and provides daily updates on drought-related weather data and predictions.
Some plants can take the heat better than others can. Choosing drought-tolerant crops and varieties is one savvy strategy of water-wise gardeners. Browse a chart of our top recommendations.
Contributing editorBarbara 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+.