The Pacific Northwest has an abundance of rain during the winter, but summers are usually dry when plants need the most water. The goal of Water Wise Gardening is to conserve water by using it efficiently. But, it is not necessary to go the extreme of planting only plants that never need watering.
The main components of Water Wise Gardening are: choosing plants which need less than average water, grouping plants according to water needs, preparing the soil properly to encourage a large root system to gather water, and conserving water with drip irrigation and mulch.
Plants which need less water usually fall into two groups: plants from arid climates which need less water year round and dry summer plants which grow and flower in the winter and spring and need little water during the summer. Arid plants include cactus, succulents, some grasses, pines and junipers. Dry summer plants include heather, brooms, spring flowering bulbs and native plants, such as Oregon grape and native dogwood. See my article on Oregon Native Landscape Plants.
There are a few fruits that require less water. Apricots, Figs, Grapes, Peaches, Pineapple Guavas, and Pomegranates require little additional watering once they are established. The other fruits and vegetables require regular watering through the summer. Some vegetables can get by with less water because they can be planted in the early spring or fall when there is natural rainfall. Broccoli, cabbage, cauliflower, onions, peas and lettuce will grow well in cool weather. They can be planted as early as March. All but peas and lettuce can be planted as late as September. The cooler weather also encourages them to grow without going to seed (bolting).
By grouping plants according to water needs, it is possible to use the minimum amount of water. It wastes much water to have a plant that needs a lot of water in with plants that do not need much water. My Calendar of Color pages includes information about the water needs of trees, shrubs, vines and perennials.
Several simple methods can be used to conserve water. Put a hose shut off on the end of a hose and use a watering wand to put water where it is needed. Use drip irrigation so the water goes directly into the soil and does not evaporate into the air. Run sprinklers at sunrise when the air is cool and there is less wind. Add rain sensors and soil moisture sensors to automatic sprinklers so they do not run when the soil is moist. Spread tuna cans around the yard to see how much water is being applied. Never apply more than one inch at a time, or a half-inch on lawns and annuals.
Plants will use water much more efficiently if they have a deep root system. They can go longer without needing to be watered since they can draw from a larger volume of soil. Heavy clay soil prevents roots from growing deep because of a lack of oxygen deep in the soil. Properly preparing the soil makes more improvement in growth and production than any other one thing. The ideal soil would contain roughly equal amounts of sand, silt, clay and organic matter, with good aeration and drainage at least one foot deep. This allows the soil to soak up natural rainfall and allows roots to grow deep and wide so they can use all of the available moisture. Soil amendments, such as compost and Profile Soil Conditioner, should be added to the soil and dug or tilled into the top foot of soil.
To encourage deep roots, water deeply by applying about an inch of water, once or twice a week instead of every day. It takes about an inch of water to wet one foot of a well-prepared soil or heavy clay. For most plants, the soil surface should dry before it is watered again. This may take two days or two weeks, depending on the weather and the number and size of the plants.
A more accurate way to determine soil water needs is to use a plant water meter. It will indicate soil moisture at the surface as well as deep in the root zone. There are also soil moisture sensors that can be attached to automatic sprinkler timers. With these, the water is only applied when the soil actually needs it. For maximum growth and yields, the soil moisture should be held at field capacity, which is when excess water has drained away and there are air spaces between the particles. Vegetable yields have been doubled by applying controlled amounts of water at regular intervals on well-drained soil to maintain field capacity. Field capacity can be maintained on a small scale by punching a small nail hole in the bottom of a coffee can and burying it. Filling the can every day should maintain the soil near field capacity within two or three feet of the can.
Water can also be conserved by using mulches. They absorb water and hold it until it can soak in instead of running off. An inch or two of compost or bark dust also keeps the soil cooler so the water does not evaporate as fast. Do not cover lower branches or pile mulch more than an inch deep around the stem, or diseases may develop. Also, do not let mulch build up to more than four inches deep, or problems may develop. Decorative rock may increase water use because it transmits heat to the soil and reflects heat onto the plants. Black plastic does not work well as mulch because it does not let rain soak in, but landscape fabric allows both water and air to move into the soil.
Mulching is a very effective way to conserve water in vegetable gardens. Newly planted seeds can be watered, then covered with damp newspaper. They will not need to be watered again until the plants emerge. Just be sure to remove the paper immediately so the plants do not overheat. Mulch also prevents a crust from forming on the surface of the soil, which hinders seed emergence. Weeds can waste quite a bit of water. Weeds are prevented or reduced by the use of mulches. Weeds are also reduced by planting plants close together so they shade the soil. Weeds can be prevented with Treflan Weed Preventer on some fruits and vegetables. Read and follow the directions carefully. Roundup can also be used to kill weeds before planting. My favorite tool for controlling weeds is an Ames Action Hoe, which cuts under the weeds without moving the soil or mulch.
In lawn areas, a higher mowing height shades the soil more and keeps it cooler. Lawns will use less water if they are mowed higher at 2.5-3.5 inches. Even more water can be saved if lawns are not watered at all. An unwatered lawn will usually stay green for a few weeks if it is not mowed. Lawns which are mostly fescue grass will quickly recover when fall rains begin. However, ryegrass lawns do not tolerate drying up and turning brown. They will develop bare spots which have to be reseeded. I recommend either watering ryegrass lawns enough to keep them green, or reseeding the bare spots every fall with a fescue grass seed until the lawn is mostly fescue.
Water Wise Gardening will lower your water bill as well as increase the growth and yields of fruits and vegetables and improve the appearance of your landscape. It just makes good sense.
Common and Scientific Names of Trees, Shrubs, Vines & Perennials
Spring Perennial Color| Summer Perennial Color| Fall Perennial Color| Winter and All Year Perennial Color
Spring Shrub Color| Summer Shrub Color| Fall Shrub Color| Winter Shrub Color| All Year Shrubs
Spring Tree Color| Summer Tree Color| Fall Tree Color| Winter Tree Color
Spring and Summer Vine Color| Fall and Winter Vine Color and All Year Vines
More information can be found on my webpages:
Annuals, Biennials, Perennials and Bulbs | Edible Landscaping | Fall Planting | Fruit Tree Tips
Herbs for the Kitchen and Landscape | House Plants | Improving Soil | Landscape Design
Lawn Care | Oregon Invasive Plants | Oregon Native Landscape Plants | Pest Control
Plant Nutrients | Plant Propagation | Planting a Vegetable Garden | Planting in Clay Soil
Pruning for Shade, Flowers and Fruit | Remove Trees Roots and All | Rod's Garden Pruning
Roses | Seasonal Pruning Guide | Trees and Shrubs in the Landscape
Water Wise Gardening | Winter Plant Protection
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