University of Maryland Extension

Drought Conditions - Trees and Shrubs

drought damaged leaves

Photo: Over a prolonged period drought will cause serious damage, such as leaf scorch, browning or early leaf drop

Back to Common Problems - Trees and Shrubs

Maryland frequently experiences hot, dry conditions during the summer months. Exceptionally dry conditions in fall, winter or spring can also have a negative impact on your landscape. When drought conditions are prolonged, landscape plants, trees and lawns may suffer temporary or permanent damage.

early fall color from drought conditions
Early fall color can be a sign of drought stress
drought symptoms
Browning of foliage
leaves wilting
Wilting for short periods of time does not harm plants
severe drought symptoms
Over a prolonged period drought can cause serious damage
drought damage holly
Extended drought damages leaves and berries on holly

Wilting is a condition brought about in plants when roots are unable to supply sufficient moisture to the stems and leaves. Wilting for short periods of time does not harm plants. Sometimes a plant wilts on a hot day because moisture is evaporating from the leaves faster than the roots can supply it. If there is ample soil moisture, the plant will absorb water in the evening to firm up the stems and leaves. Over a prolonged period, however, drought will cause serious damage, such as yellowing, leaf scorch, browning, early fall color or early leaf drop. Extended periods of drought may also damage berries or inhibit flower bud formation. Severe heat and water stress when a plant is in bloom may cause scorching or browning of flower buds and blossoms. Plants vary in their ability to tolerate drought and some may die suddenly after extended periods of drought.

In late summer or early fall it is not uncommon to experience a sustained period of wilting, particularly of broad-leaved evergreens such as rhododendrons. The latest research has shown late summer drought to be the cause of leaf damage typically attributed to winter desiccation. When the leaves hang down and no rain is predicted, it is advisable to provide prolonged, deep watering to keep the leaves rigid. To wet the soil at least 6-inches deep requires 1- to 2-inches of surface water (65-130 gallons water per 100 square feet).

Well-established groups of woody plants should be watered every 10 days during prolonged dry spells. Since root systems of established plants are rather widespread and deep, it is vital that enough moisture be put down to reach them. If a sprinkler is set up to water a group of plants, a coffee can should be placed in range of the sprinkler. When 1-inch of water accumulates in the can, 1-inch of water has been distributed in the soil, which is enough to penetrate 6- inches of soil.

wilting pine
Early wilt symptoms on pine include drooping or pendant needles
needle dieback
Prolonged drought will cause needles to turn brown and will eventually drop
needle drop and branch dieback
If drought conditions persist, eventually needle tips will turn brown (scorch) and branch tips will show needle drop or dieback, followed by death of the tree
yellowing pine needles
Premature fall needle coloration may also be symptomatic of drought injury

Most evergreens have shallow root systems and are among the first trees to exhibit signs of drought stress. The first symptom of drought stress is wilting. Early wilt symptoms include drooping or pendant needles. These wilt symptoms may first appear in the late afternoon. Prompt watering will alleviate the symptoms. If drought conditions persist, eventually needle tips will turn brown (scorch) and branch tips will show needle drop or dieback, followed by death of the tree. Premature fall needle coloration may also be symptomatic of drought injury.

Container-grown landscape plants may be susceptible to drought stress once they are transplanted into the landscape. The organic mix in which plants are grown in the nursery is prone to rapid loss of moisture due to plant transpiration (loss of water from plant leaves) and evaporation from the soil surface. Even though moisture is available in the soil surrounding the organic mix, it does not move into the transplanted root ball rapidly enough to prevent moisture stress.

Available moisture in the container mix can be depleted in about two days in the absence of irrigation. For this reason, nurseries water at least every other day. This routine should be followed after transplanting until the root system establishes itself (approximately three to four weeks.)

Practice effective watering:

  • Know your soil. Observe how quickly soil dries out after a rain or watering. Clay soil drains slowly, porous sandy soil quickly. Adding organic matter to the soil will increase drainage in clay soil and moisture retention in sandy soil.
  • Learn the cultural requirements of your plants. It is particularly important to supply relatively high soil moisture for evergreen plants during the fall before the ground freezes. The leaves of such plants continue to lose water during the winter, especially when the temperature is above 40°F. If the soil is dry, the plants may become desiccated, turn brown, and die. Water shrubs several times during the late fall, if the soil moisture supply is low.
  • Mulch plantings to reduce the frequency of watering during dry spells. Mulches keep soils cool and reduce water loss through evaporation.

One of the most effective watering methods is trickle irrigation. When combined with a layer of mulch, this method allows plants to use nearly all of the added water. A trickle system discharges small quantities of water on a regular basis directly to the root zone under a tree, shrub, or row of garden vegetables or flowers. Very little water is lost to the air through evaporation. The application rate can also be controlled to meet the needs of the crop and the drainage capacity of the soil.

When there is an extended period without rain during the summer, new plants should be deeply watered once a week. By allowing the soil surface to dry out somewhat between waterings, roots grow deeper into areas where soil moisture is highest. The roots of plants watered frequently, but lightly, are close to the surface, making the plants more vulnerable to wilting. They will not become well established and will have little drought tolerance. This can occur with automatic overhead sprinkler systems that are designed to go on for a short period of time each night and only moisten the surface. The practice also encourages foliar diseases in mid-summer.


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