Purdue
University
Consumer Horticulture
Department of Horticulture and Landscape Architecture
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Purdue
University
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Released 17 May 2001
by B. Rosie Lerner, Extension Consumer Horticulture Specialist
Gardeners continue to be challenged by Mother Nature this spring as
the hot, dry weather immediately followed a mid-April freeze. And
it's not like we had much moisture going into the current growing
season!
Most gardeners are accustomed to watering flower beds and vegetable gardens, though maybe not so early in the year! These plants require approximately 1 - 1 1/2 inches of water per week to maintain healthy flowers, foliage, roots and fruits. In times of drought, established plants may tolerate 10-14 days between waterings, but be aware that problems, such as fruit cracking, blossom end-rot, and blossom drop, will increase.
Watering is most critical during seed germination, transplant establishment, pollination and fruit set for most horticultural plants. Use a mulch, where possible, to conserve what moisture there is. Mulch reduces water loss to evaporation, as well as reducing weed emergence. You don't want your plants to share what little moisture they have with weeds!
The best way to apply the water is by thoroughly soaking the soil with the prescribed amount of water in one slow application. This deep watering will encourage deeper root growth that in turn will be better able to withstand the drought. Frequent shallow watering encourages shallow roots, which are more likely to succumb to heat and drying of the top soil. Sandy soil and containerized plants will need more frequent irrigation.
Many evergreens around the state are showing lots of brown needles. Many trees, shrubs and perennials that were in bud or newly leafed out during the freeze are now showing signs of brown or black along the edges of the leaves, if not worse. Now, as these plants are also battling drought conditions, this leaf scorch is likely to worsen. While minor cases of leaf scorch are not terribly harmful to the plant, prolonged lack of moisture can spell disaster for landscape plants.
Young and newly established plants are most susceptible to the dry conditions, but even established plants may reach a critical point during prolonged drought. Branch dieback, combined with eventual root death, will make plants more susceptible to winter injury. Plants that were already under stress from other factors may succumb to severely dry soils.
Keep in mind that next year's growth will be determined by buds that form this fall. Flower buds for many spring-flowering and fruiting plants will also be developing this autumn. So, even if your plants aren't showing any symptoms now, the damage may become apparent later.
Watering of landscape and fruit plants should be aimed at where the roots naturally occur. While these woody plants do have some roots that grow very deep, most of the feeder roots that are responsible for water uptake occur in the top 18 inches of soil. Most of these feeder roots are concentrated near the dripline of the leaf canopy and beyond, not up close to the trunk. Allow water to thoroughly soak the target area by applying water at a slow enough rate to allow penetration rather than wasting water by runoff. Don't apply the water any faster than 1 inch per hour. As with annual plants, mulch will help prevent moisture loss due to evaporation.
The ideal time to water is during the early morning hours, ending by 8 a.m. This makes maximum use of water while allowing foliage to dry. Watering during mid-day when temperatures are high, sunshine is strong and winds are brisk wastes substantial water. Watering in the evening or at night is convenient for many, but can make plants more susceptible to disease infection by providing the moisture that fungi and bacteria need to grow.
Last updated: 6 April 2006
For questions concerning this page, send a message to homehort@purdue.edu.
The URL for this page is http://www.hort.purdue.edu/ext/earlydrought.html