Harvest the rain for your summer garden
Where rainfall and irrigation water are commonly in short supply – here in the Sonoma Valley and in most of California – dry-gardening is a partial longterm solution for those who love to garden. Dry-gardening is a technique used by gardeners in regions around the world where 20 inches of rain or less fall each year.
Dry-gardening is not gardening with no water; it’s gardening with limited water and making the most of the water you have.
Want to give dry-gardening a try this year? Here are four goals you can set:
• Store annual rainfall in the soil for later use.
• Grow plants and crops suitable for growth under arid or drought conditions.
• Plant ornamentals and crops further apart than you would where there is ample water.
• Prevent direct evaporation of soil moisture during the growing season.
Dry gardening techniques
Here are simple practices to accomplish these goals and become a successful dry gardener:
• Add organic matter to your garden now. Add aged compost and aged manure; the more the better. Add at least one to two inches of compost to your garden twice a year in late winter or spring and again in autumn. Organic matter will improve all soils and will help your soil retain water.
• Mulch around plants to retain soil moisture, block weeds, and promote a steady soil temperature. Apply mulch around established plants now and early in the summer to slow evaporation. Use aged compost, leaves, grass clippings, straw, pine needles, even newspaper. Be careful not to apply compost directly next to plants stems; this could cause the stems to rot. Mulch a few inches back from established and new plants; this will protect the soil from drying winds and the sun next summer.
• Do not allow weeds to grow in your garden. Weeds complete with plants and vegetables for water, nutrients, and light. Handpick weeds when they are just two or three inches tall. Or lightly cultivate weeds exposing their roots to drying wind and sun. Never allow weeds to set seed in your garden and multiply.
• Cultivate your garden to capture rainwater. Before an expected rain, cultivate lightly in your garden. Cultivation will break up soil crusting caused by rainfall and irrigation and allow new rainfall to seep into the soil. Surface cultivation just an inch or two deep will help capture up to 70 percent of each rainfall. Cultivate lightly after every rainfall to break soil crusting. (Be careful not to cultivate too soon after a rain – walking on very wet soil can cause soil to compact.)
• Reduce the number of plants in your garden and space them further apart than normal; this is a basic dry gardening concept. Set plants at least 1 times or greater than the spacing distance recommended in garden books or on seed packets. When fewer plants are in the garden, there will be more water to go around. For example in your vegetable garden, bush tomatoes that might normally be planted on three-foot centers should be planted on four to six foot centers. (If you are a vegetable gardener, it is important to note that seeds must germinate under normal conditions; that is they must receive moisture to begin life and grow. Give seeds and seedlings all the water they need until they are established.)
• Capture rainwater from rain gutters (not rooftops) in a large garbage can placed under a rainspout. This water can be used to water the garden next summer and to make compost tea. Compost tea is a rich natural plant food. You can make compost tea by combining equal parts water and aged compost. Compost tea delivers nutrients directly to the plant roots in soluble form. Remember, plants “drink” their food.
• Water plants deeply but infrequently once the winter rains pass. Plant roots follow the moisture. Next summer, water deeply by watering at a trickle allowing water to seep slowly down into the soil. Water at night at the base of plants, or water in morning if you expect irrigation will hit plant leaves (this will allow leaves to dry before nightfall and avoid disease).
• Use drip irrigation or a soaker hose if you irrigate. Set drip irrigation at the base of plants where the water will go quickly to roots. Cover drip irrigation with a light mulch of compost to slow soil surface evaporation. Place your irrigation on a timer.
• Windbreaks. Protect your garden soil and plants from drying winds with a windbreak. Locate your garden away from prevailing winds behind a hedge or fence. Protect your vegetable garden with sunflowers which can be grown as natural windbreaks.
• Plant early maturing cultivars in the vegetable garden. Grow vegetable cultivars or varieties that are quicker-maturing than others. This strategy uses soil moisture early in the season while it is still available. Grow plants that require more water early in the season and allow vegetables that require less water to grow through the dry period.
• Harvest your crops on time. Take crops at their peak of growth and flavor. Don’t leave plants in the garden too long; flavor will not be enhanced and crops will deteriorate.
• Double-dig your garden to loosen the soil. When you are establishing new planting beds or reviving old ones, double dig. Double digging can help turn your soil into a sponge. Double-digging involves turning the soil a spade’s length deep (about 12 inches) and loosening the next 12 inches of soil with a spading fork. Thus the soil is turned or loosened to a depth of 24 inches. This can be hard work but a long-term investment in your garden. Double digging will loosen soil and allow water to seep deeper into your garden where it can remain until plant roots need it. Loose soil also allows plant roots to grow deeper and stronger, more readily able to withstand drought. But do not dig the soil after a rainfall (this will damage the soil) or when it is too dry; wait until it is just barely moist. A good time to double dig your garden is in the fall.
Steve Albert is the author of The Kitchen Garden Grower’s Guide available at Amazon.com. He teaches in the landscape design program at the U.C. Berkeley Extension. He lives in Oakmont.