Plants need lots of water, but not too much

Published 12:00 am Friday, July 11, 2014

SALISBURY — People who have potted and container plants may need to water them every day just to keep them alive, especially in window boxes. When the weather is excessively hot with wind, you may need to water more than once a day.
Lack of rain and low humidity can be a challenge for those with potted plants and a vegetable garden.
Even with afternoon rain showers, irrigation is a way of life for those who want to keep bedding plants, lawns and vegetables alive. The ideal time to irrigate is in the early morning to avoid evaporation during the heat of the day. Avoid irrigating late in the afternoon or at night. Even though late evening and night irrigation provides cooler temperatures, it also the perfect environment for the development of foliar diseases.
Use a rain gauge to measure water if you use overhead irrigation to determine if you’re applying a sufficient amount.
Shallow irrigation can be of no real benefit and may cause more damage by creating shallow root systems. Check the soil often to make sure plants are receiving an adequate water supply. If you have a drip system, place a small plastic cup beneath the hose to measure the amounts from the emitters.
Automatic timers ease the task of irrigation and reduce waste by eliminating over-watering. Timers meter water by gallons or by amount of irrigation time desired.
There is really no valid way to determine how much to water a plant or a garden area in a week. Plant species, soil types and exposures are only a few variables that confuse even the most experienced gardener. Obviously, newly planted shrubs and trees will need more water than well-established ones.
Dogwoods, rhododendron, azaleas and camellias have shallow root systems, easily drying out in dry weather, and will need extra water.
Remember, do not over-water wilting shrubs, as this can kill trees and shrubs much quicker than droughts. Hydrangeas often wilt during the heat of the day but become turgid in the evening and early in the morning. Therefore, close examination early in the morning is the best time to gauge when to irrigate.
Mulching is one of the cheapest and most effective methods of water conservation. Three or more inches of organic mulch such as bark or pine needles conserves soil moisture. Wheat straw, shredded newspaper and other organic material should also be used in vegetable gardens as an aid in conserving moisture, especially around tomato plants and other plants that are heavy drinkers.
Moisture holding crystals/granules are also available and can be added to soil mixtures to help hold water. The crystals turn into jelly-like beads that are designed to provide water to plants and reduce watering. There is some controversy as to whether these actually work, however many like them. Read the instructions carefully as some of these products cannot be applied to vegetables and other edible plants.

Darrell Blackwelder is county Extension director of Rowan County North Carolina Cooperative Extension. Call 704-216-8970.