I’ve been a landscape designer for nearly 40 years and this is my third major drought here in California, and this year it’s a “doozy.” I would like to share with you some of my experiences and how can we all use our water more wisely for now and in the future. First, we must cut down or eliminate our lawns, that’s for sure. We should all use drip more and recycle water when we can. That would help local water districts in many ways. What is not as obvious is that we all need to plant lots of vegetables and fruits, Yes!! According to www.Treehugger.com growing the average pound of lettuce commercially uses 15 gallons of water, tomatoes 22 gallons, and a pound of potatoes 30 gallons. Years ago, John Jeavons, author of the best selling How to Grow More Vegetables, concluded that the home gardener, using organic techniques to grow edibles, uses between one quarter and an eighth as much water as does the farmer. Efficient home gardeners can save this entire country plenty of water and eat much better to boot. (BTW, the price of produce is going to sky rocket this year as more than half of this nations produce is grown in CA and many farmers must leave their land fallow.)
When grown using organic techniques and drip irrigation, home-grown tomatoes, peppers, squash, basil, and onions not only taste better, compared to agriculture, they use less than half the water.
Before we discuss edibles let’s first look at the ways you can globally save water. In the house, if you have not already done so: install efficient toilets and washing machines, take shorter showers, and try not to pre-rinse dishes for the dishwasher. For more global ways to save water in the house, go to the websites for Santa Clara Valley Water District www.valleywater.org and Environmental Protection Agency www.epa.gov/.
Saving water in the landscape – Californians use more than half their household’s water on landscaping, so the biggest water savings can be made here. Below are some ways to cut down on water use in the garden.
- Incorporate organic matter in your soil – 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 2.5 times more than it would normally hold. 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 (aka compost) equals 40 pounds of water retention.
Annual vegetables like peppers and zucchini use far less water when generous amounts of organic matter is incorporated into the soil and a 3 or 4” mulch of well-aged compost or other organic matter is used to cover the soil. Add drip irrigation and vegetables can be grown using far less water than the farmer.
- Mulch heavily – 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 earwigs that can hide in the mulch. To prevent diseases, keep the mulch 6” away from the crown of annuals, shrubs, and tree trunks.
- Water deeply and infrequently – Surface roots dry out faster than those at least 6” deep. Set your irrigation timer 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. You can also use a spade it’s just that the probe is less work. 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.
- Install a drip system – Use drip 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. That said, a well-thought out system will save many headaches. To be realistic, drip takes effort to install and attention to keep it running well. Hints: 1. Avoid cheap irrigation “kits.” They can be unreliable. It is hard to find replacement parts for repairs and cheap plastic tubing can expand in hot weather forcing the emitters to pop off. 2. Instead, use professional grade in-line emitters that drip water from holes in the line rather than a solid tubing system with installed emitters. 3. Choose “shrubblers” and micro-sprayers for annuals in containers; look for flow control so you can adjust the water pattern for changing individual plants. 4. Install a good filter and change it every few months. 5. Cover the tubing with mulch, not only because it looks better, but because it protects the plastic from ultraviolet light so it lasts longer. 6. Run the system every few weeks to make sure that there are no leaks or clogs.
You can have an irrigation specialist install your system or for DIY, seek out information on line. The Urban Farmer Store in San Francisco (www.theurbanfarmerstore.com) , Harmony Farms Supply in Sebastopol, CA (www.harmonyfarm.com/ ) and/or Peaceful Valley Farm Supply in Grass Valley, CA (www.groworganic.com) all have web sites with extensive information for installing drip, watering schedules, and lots of equipment options.
Deep water trees and shrubs – 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. Use an old plastic 5 gallon pail or garbage can. If it doesn’t have a few holes in the bottom make them, you want the water to leak out slowly. Move it to the drip line of the plant and fill it with water, grey water from your house or water from the hose and let it slowly leak into the soil, when it is empty move it to another quadrant.
Use gray water when possible – 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 as soil microbes tie up most disease organisms and toxins. Care must be used when watering edible plants. I only use clean potable water. Avoid laundry soaps that contain sodium, salt compounds and boron which can damage plants. Look for products such as Dr. Bronners for the kitchen and bathroom sink and Oasis for your laundry. For much more information on gray water and soap brands consult www.greywateraction.org.
Install rain barrels – What you say? Why have rain barrels in a drought when we are getting so little rain? Yes, I use two 75 gallon barrels all year long to store gray water to water my plants. For a diagram and guidelines on how to best use rainwater see the city of Berkeley’s website under: Rain Water Harvesting for information; and Gardeners Supply, www.gardeners.com/ and the Urban Farmer Store for rain barrels and how to set them up.
All my favorite culinary herbs can be grown in a few recycled wine barrels. Notice that one is a smaller one nested on top of a large one. Here Thai basil, chives, savory, tarragon, sage, French sorrel, and thyme are grouped together and watered by drip irrigation on an automatic timer that comes on twice a day for 3 minutes all summer. A bonus container of strawberries is on the same system.
If you have any other ideas let me know in the comments section below!
Rosalind Creasy – Landscape Designer and author of Edible Landscaping, Sierra Club Books, 2010