Gardening For a Long Dry Summer
Posted by Grange Co-op on 1st Jun 2012
Note: This article was written for a drought year but the advice is relevant for any summer...
The winter has been drier than usual here in the Pacific Northwest, so there is not as much moisture stored in the soil. Watering may be limited in some places because of this year's drought. Aside from these considerations, the summer we are facing is much like any other summer. The Pacific Northwest has a Mediterranean climate, with very little rain from June to October. This year's drought is a good reason to practice doing what it is always good to do: conserve water. In the U.S, half of household water is used for irrigation, and according to some estimates, half of the irrigation water is wasted. Not only this year but also every year, water is too precious to waste.
Making the best use of water involves rethinking gardening a bit. One important concept is watering zones: a small oasis zone, probably near the house, with plants that have higher water needs, every week or even more often, and perhaps a pond; a middle zone, with plants that grow best with summer water, but less often; an outer zone for drought-tolerant plants that require no summer water once established.
Not only does this save water, it saves time! Less time watering means more time to relax and to do other work in the garden. Ideal plants for the outer zone are native plants, adapted to winter rains and dry summers, but the natives you choose must be those that grow well in your garden's soil and light conditions. Summer in a forest, for example, differs greatly from summer in a meadow, because the forest moderates heat and stores water for denizens of the understory.
You can choose drought-tolerant plants from other parts of the world as well, but be aware that many of them need good winter drainage. You can plant them on slopes and you can amend soil with organic matter to improve drainage, but building raised beds for them won't work so well. Raised beds, especially narrow ones, dry out faster than flat soil and then you need more water. Even drought-tolerant herbaceous plants need regular watering their first summer in the garden. In subsequent summers, they can be watered infrequently or not at all, depending on the plant species and the length and intensity of summer heat. For drought-tolerant trees and shrubs, the first two years are important, while plants' roots get established. Before you water, however, it's important to feel the soil to see whether it is drying out. If you have a thick mulch and soil that retains moisture well, you may not need to water so frequently.
Thoughtful watering is important in a dry summer. Watering for a long time at infrequent intervals (rather than a little water every few days) is a crucial first step, even for young plants. Plants that receive frequent short watering spread their roots near the surface of the soil and are prone to drought; infrequent watering encourage plant roots to dive in search of moisture. Drip irrigation and soaker hoses are especially efficient ways to irrigate because they bring water directly to plant roots. Soaker hoses work best under the weight of 4 inches or more of mulch, which helps spread the water through the soil. Unmulched soaker hoses release only narrow vertical trickles of water.
Overhead watering can waste a lot of water, but waste can be reduced by watering early in the morning. When the air is warm, in the middle of the day, a great deal of water is lost in evaporation. Although overhead watering in the evening can encourage leaf diseases, it is sometimes more useful simply to find more watering hours while the air is cool. Do it only in areas of the garden where the plants are not prone to disease.
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Working with the soil can help plants a lot in dry summers. Mixing organic matter in soil increases its water retention. Mulching soil with organic matter - compost, shredded leaves, dried grass clippings - reduces evaporation from the soil surface and keeps plant roots cool and evenly moist. Where mulch is thick, water under the mulch, or make sure you water deeply enough for water to reach the plant roots. Avoid using bark mulch near plants. As it decomposes, it uses nitrogen that nearby plants need to grow.
Generous plant spacing and careful weeding can help reduce water needs. Crowded plants compete with each other for water. 12 inches apart is a good spacing for annual flowers, 18 to 24 inches apart for perennials, and even more for large vegetables. Think of each plant's spread at maturity: that is how far its roots spread under the ground. Plant leaves that touch the ground reduce evaporation, but plants whose leaves overlap crowd each other and cause waterstress.
Lawns are big water users, so planting grass only where you need it for rest and play reduces water use, as well as human energy drain. Rye, fine fescues, and ecolawn mixes are easiest to care for. Grass clippings can be composted or spread; water grass once a week, or consider letting some or all of your lawn turn golden brown for the summer. It will green again with winter rains as long as you leave it brown ALL SUMMER. If you let grass stay dry for awhile, then water it once or twice, then it turns dry again, it will use up its reserves and die.
When you are choosing drought-resistant plants for your garden, it helps to consider the plants' natural habitats. Many degrees of drought tolerance exist, depending on the soils, slopes, summer temperatures, and rainfall patterns of the plants' home ranges. Plants that have leaves, which are hairy, thick, succulent, or leathery, gray-green or silvery, are often drought-tolerant. Drought-tolerant plants may be native to deserts, seashores, mountain slopes, areas with thin soils, dry open fields, sunny roadsides, and dry woods. Certain plant families have high likelihood for drought tolerance: grasses, legumes, poppies, and many members of the daisy family. Plants from the Mediterranean climates are good bets: not only our own Pacific Northwest, but parts of Australia, and South Africa, coastal California, and of course, areas near the Mediterranean Sea.
Although this drought year is a challenge for the Pacific Northwest gardeners, it is also a good opportunity. We can learn to use water with respect, both now and during our usual long dry Northwestern Summers.
Copyright 2001 Kate Rogers Gessert for Log House Plants