Most areas in Iowa have been extremely dry since last summer. Because of the dry conditions, some home gardeners have begun to water their perennial beds and lawns. Important points for gardeners to remember when watering include:
1. Water deeply and infrequently. Deep watering promotes the development of a deep, extensive root system. Frequent, light watering promotes shallow rooting. Deep-rooted plants will be able to survive hot, dry weather much better than shallow-rooted plants because they will be able to reach the moisture deep in the soil.
A deep watering once a week should be adequate for fruit, vegetable, and flower gardens. Apply 1 to 1 1/2 inches of water per week. A weekly application of 1 to 1 1/2 inches of water is also adequate for turfgrass. Newly planted trees and shrubs should be watered deeply every 7 to 10 days during dry weather. Small trees and shrubs usually require watering for 1 to 2 growing seasons. It may be necessary to water large trees for 2 to 3 years.
When watering gardens and landscape plantings, soil characteristics and weather conditions actually determine the amount and frequency of watering. For example, sandy soils require more frequent watering than loam soils.
2. Water uniformly. Uniform application of water prevents waste and produces even growth.
3. Water efficiently. When irrigating with a sprinkler, early morning is the best time to water. A morning application allows the water to soak deeply into the ground with little water lost to evaporation. When watering is completed, the plant foliage dries quickly. Watering at midday is less efficient because evaporation is rapid and strong winds may cause uneven water distribution. Strong midday winds may also carry water onto driveways, patios or streets, wasting considerable amounts of water. Watering lawns and gardens with a sprinkler in the evening or during the night may increase disease problems.
In the fruit and vegetable garden, drip irrigation systems and soaker hoses are generally more efficient and cause fewer disease problems than sprinklers. Mornings and evenings are excellent times to water gardens when using a drip irrigation system or soaker hose.
4. Mulch landscape plantings and garden areas to conserve soil moisture. Mulching reduces the rate of evaporation from the soil surface and also limits weed competition. Organic materials, such as grass clippings, straw, and shredded leaves are excellent mulches for the vegetable garden. Wood chips, bark, and ground corncobs are good choices for perennial beds and trees and shrubs.
Despite the dry weather, proper watering practices can help insure attractive annuals and perennials, productive fruits and vegetables, and the survival of recently planted trees and shrubs. Proper watering also saves time and money.
This article originally appeared in the May 5, 2000 issue, p. 45.