Garden Know-How: Wise Watering

Organic mulches and the right watering equipment will keep your crops healthy and your yields abundant.

| June/July 2007

In a perfect growing season, 1 inch of gentle rain falls each week. Gardeners dream of such a season, but plants know better than to expect perfect weather. In response to dry conditions, they close their stomata (the thousands of “breathing” pores located on both sides of the leaves) to limit moisture loss, and send roots deeper in search of water. Roots change their growth pattern to accommodate wet conditions, too, often staying close to the surface where they have better access to oxygen.

These are admirable talents, but few plants are water-handling acrobats. Compared to your area’s native plants, most food-garden plants are amateurs at adapting to your local rainfall patterns, so 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 watering system in place, preserving water through mulching and finding innovative ways to work out the kinks in your garden’s water supply.

Newly planted seeds, transplants of any kind and plants grown in containers almost always need supplemental water. Plan ahead to provide water in these situations, which can usually be 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. Use upturned flowerpots or other shade covers to make sure the soil around newly planted seedlings stays moist, and to reduce overall transplanting trauma. Remove the covers after a few days.

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 (leaves, compost, clean grass clippings, etc.) 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 and Types Need Different Techniques

Mulching cannot do it all. To enhance the flavor, nutrition and productivity of your garden plants, sooner or later you will have to supply water. Your goal is to simulate drenching rain that replenishes moisture throughout your plants’ root zones. Any soil will accept and retain water better if it contains plenty of organic matter, but 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.

Sprinklers are fun to use, but depending on weather conditions, half the water that runs through them can be lost to evaporation and runoff. Occasionally there are good reasons to use a garden sprinkler. If very dry weather hits just as corn shows its silks and tassels, or when tomatoes are in full bloom, a late afternoon sprinkling session 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, a cover crop of buckwheat, for example. Watering by hand is more efficient than sprinklers, but doing it right eats up hours of time.

7/15/2011 4:04:59 PM

There is an ancient method of watering (from both Mexico & China) which uses clay pots. They are called Ollas. They are terracotta pots with narrow necks. You bury the pot in the ground up to the neck and fill with water. The water gradually seeps through the unglazed terracotta and there is almost no water evaporation. Cover the top of the neck with a stone of the appropriate size to keep bugs out. Ollas come in sizes from a quart to a gallon and a half. The pots work wonders, especially in places like California, Arizona, and New Mexico. They work in most soils except heavy clay. They are available from at least 2 online sources: Peddler's Wagon & East Central Ministries. They are sustainable and will last forever, given good care. They are great with tomatoes & squash especially. I keep getting more each year. -- Eloise in San Jose, CA

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