Written by Rosalind Creasy, 2015, Seed Savers Exchange
Where and when you water your plants really does make a difference when it comes to plant health and water conservation. Be sure to apply water directly to the soil’s surface. Why? Roots intake water, and plant leaves do not need to be watered. Wet leaves, in fact, only increase the probability that your plants will develop foliar (or leaf) diseases.
Watering in the morning allows leaves to dry quickly (reducing risk of disease) and conserves water.
Watering too shallowly and too frequently are among the most common mistakes gardeners make. Instead, water deeply and thoroughly—doing so encourages roots to push more deeply into the soil, where moisture levels are more consistent. That, of course, means you won’t need to water your plants as often. Remember that newly planted seeds and young seedlings/transplants that have shallow, developing root systems will need to be watered more frequently, whereas established plantings have deeper root systems and require less frequent watering.
Mulching soil around the base of plants reduces moisture loss to evaporation, conserving soil moisture and reducing the time you will spend watering your plants.
Grouping plants with similar watering needs in the garden will both decrease the time you spend watering and increase your ability to allocate water properly. Certain crops (such as onions and lettuce) as well as new plantings need shallow, more-frequent watering, whereas long-season plants like tomatoes need deeper, less-frequent watering.
It’s a good rule of thumb to water your garden when about half the available water in the soil is depleted. But how do you best determine when that is? Try digging down into the soil at least four inches and squeezing a handful of soil into a ball. When compressed in this manner, sandy soil should stick together slightly; loamy soil should form a loose ball; and clay soil should form a ball easily. If this doesn’t happen in each case, it’s time to water your garden.
Many homeowners, especially in arid climates, use more than half their household’s water on landscaping, so the biggest water savings can be made here. Here are some ways to cut down on water use in the garden.
Lack of yearly rainfall is only one factor in our current drought conditions; much of the water we use every day is actually unseen, stored underground in thousands of aquifers. We pump millions of gallons from these hidden stores each day, causing wells to go dry and land to sink, and threatening wild areas.
The United States Geological Association compares aquifers to a bank account: Rainfall is our income, and the level of ground water in an aquifer is the account balance. America, then, is on a seemingly endless spending spree, systematically overdrawing our water supply each year. Click here to learn more.
When we look to the American West the scarcity of water is plainly visible. But what can we do? How can we all use our water more responsibly now to ensure a more secure future? Shrink or eliminate our lawns? Sure. Use drip irrigation? Yes. Recycle water? Of course. Plant more vegetables and fruits? Believe it or not, yes.
According to TreeHugger, a media outlet for sustainability news, the average commercial grower uses 15 gallons of water to raise one pound of lettuce, 22 gallons per pound of tomatoes, and 30 gallons for each pound of potatoes.
John Jeavons, author of the best-selling How to Grow More Vegetables, has determined that using his Biointensive system, the average home gardener can use as little as 12% of the water a commercial grower uses for each pound of vegetables produced.
Many homeowners, especially in arid climates, use more than half their household’s water on landscaping, so the biggest water savings can be made here. Here are some ways to cut down on water use in the garden.
A 3-inch layer of compost turned into your soil at a 6-inch depth (about a shovel blade depth) is estimated to increase the water holding capacity of that soil by 250%. Soils composted in this manner can provide plants with water for up to a week between watering.
The Rodale Institute has a simple equation: 1 pound of carbon (a.k.a. compost) equals 40 pounds of water retention.
Use garden compost, pine needles, aged sawdust, fall leaves, and/or straw to mulch. For annual flowers and vegetables make sure that your compost is well aged or the soil microbes will rob the soil of needed nitrogen.
The looser the material the more you need to watch for slugs and snails that can hide in the mulch. Keep the mulch 6” away from the crown of annuals, shrubs, and tree trunks to prevent diseases.
Surface roots dry out faster than those at least 6” deep. Consider buying an irrigation timer, and set it to water for shorter periods of time and water a second time a few hours later, this way the water will penetrate more deeply. Most irrigation timers can be set to do this.
A great tool to make sure your plants are watered properly is a soil probe. Push the probe into the soil as far as you can, 6” to a foot deep or more, remove it and look at the sample and see if it contains damp or dry soil.
And use the internet to help you identify hydrophobic soil. When soil gets very dry it actually sheds water just like a dry sponge and you need to apply water slowly and let it be absorbed or most of your water will drain away.
Use drip irrigation for shrub borders, fruit trees, flower beds, and vegetable gardens. Drip irrigation is dramatically more efficient than overhead sprinklers (some experts say as much as 50%). Further, it cuts down on weeds, water runoff, and fungal diseases.
But planning is important. A well thought-out drip irrigation system will save many headaches. Drip systems take effort to install and close attention to work effectively. Here are a few tips based on my 30 years of drip irrigation experience:
Deep root-watering large trees is much more efficient than most irrigation techniques as it distributes water a foot or more below the surface. Done properly a few times a summer, it eliminates surface run off and reduces erosion and evaporation.
There are injection tools that attach to the hose and are inserted into the soil in 6 or 8 areas around the drip line of the shrub or tree and are run for a few hours at a time.
Or use an old plastic garbage can with a few holes in the bottom. Move it to the drip line and fill it with water and let it slowly leak into the soil; when it’s empty, move it to another quadrant.
Gray water is defined as relatively clean waste water from showers, baths, sinks, and washing machines. I keep a few plastic gallon buckets near my kitchen and bathroom sinks and put the buckets under the faucet when I’m bringing hot water to the sink or shower, and I use them when I rinse vegetables, my hands, etc.
Gray water is suitable for use in the garden because soil microbes tie up most disease organisms and toxins. When using gray water, avoid laundry soaps that contain sodium, salt compounds, and boron which can damage plants. Look for biodegradable products if you plan on using gray water.
Rain barrels are a natural for rainy climates, but how about in arid climates? I have found my two 75 gallon barrels quite useful. Certainly I collect rain water during our rainy season, but I also use them all year long to store gray water from the house to water my plants.
For a diagram and guidelines on how to best use rainwater see the city of Berkeley’s website for information.
