How to save your garden plants during drought and heat waves

Prolonged droughts and heat waves are expected to become more common in the coming decades, with parts of the US already experiencing what scientists call a “megadrought.”

Droughts are periods of abnormally dry weather that persist for relatively long periods of time. In addition to broader societal impacts, such as potential crop damage and water shortages, droughts can also have a devastating impact on garden plants.

So how can you care for your garden during these hot, dry conditions?

How does drought harm plants?

Drought stress occurs when water loss through the leaves exceeds the plant’s ability to draw water through its roots, said Lucy Bradley, a horticultural scientist at North Carolina State University Extension. news week.

This interferes with several important processes, including photosynthesis (the conversion of food into energy); transpiration (the movement of water through the plant and the evaporation of certain parts, which helps to cool it down); the “turgor” pressure that causes the plant to become stiff and rigid; and the growth of root hairs, which draw water and nutrients from the soil.

Perhaps the most significant effect of drought on plants is the reduction of photosynthesis, which is the process by which plants create food from sunlight, providing the energy (in the form of sugar) to grow, produce flowers and fruits and reproduce.

“Prolonged drought can lead to a complete collapse of the photosynthetic machinery, and it can take a long time for plants to rebuild their roots and internal mechanisms,” said Vijai Pandian, horticulture educator at the University of Wisconsin-Madison Extension Division. news week.

“This can cause long-term impacts … and the symptoms of the drought effect often continue for [the] years to come,” he said.

In the short term, drought can lead to leaf wilting and scorching, leaf loss and branch dieback, among other symptoms, according to Heidi Kratsch, a horticultural specialist at the University of Nevada, Reno Extension.

“Over time, drought can weaken plants, making them less productive and more susceptible to insect pests and disease,” Kratsch said. news week. “Drought-stressed plants can also create a fire hazard in wildfire-prone areas.”

What can you do to protect plants in a drought?

According to Kristine Lang, horticultural specialist at South Dakota State University Extension, effective water management is key.

“Once plants have been in the garden for several weeks and have established roots, watering deeply once or twice a week to thoroughly saturate the soil and encourage deeper rooting of established plants is more beneficial than light watering every day. every day,” Lang said. news week. Deep rooting helps plants survive drought conditions.

“When irrigating, it’s important to water the soil rather than wetting plant leaves, which can actually contribute to the spread of certain plant diseases,” Lang said.

Stock Image: A yellow flower on a background of dry, cracked soil. How can you protect your plants in a drought?
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During drought conditions, it is recommended to water early in the morning when air temperatures are cooler to ensure water can reach plant roots.

“Avoid irrigating when it’s windy, as wind increases soil moisture evaporation and makes overhead irrigation less efficient,” Kratsch said.

Using a soaker hose or installing a drip irrigation system where possible can also be beneficial. “Drip irrigation applies water directly to the soil where the roots are and minimizes runoff of excess water in unplanted or paved areas,” Kratsch said.

According to Pandian, the trees should be thoroughly soaked once or twice a week. Meanwhile, newly planted trees and shrubs (1-3 years old) need watering twice a week to a depth of about one inch (0.6 gallons of water is needed to cover one inch of depth per square foot).

You can use a long screwdriver or soil probe to test the depth of water movement in the soil.

For gardeners who have plants in containers, hanging baskets and pots, you may need to check if they need water every day or two, depending on the size of the container, Lang said.

Applying a layer of material to the soil surface, a technique known as mulching, can also be beneficial. “Covering the garden soil surface with an organic material such as straw or wood chips can help retain soil and keep the soil surface around the plant cooler,” Lang said. “This also reduces weed competition, which becomes even more important during drought conditions.”

Erecting temporary shade structures around heat-sensitive plants can also help prevent excess water from evaporating from leaves.

a man watering plants
Stock Image: A guy watering his garden. Water management is key to protecting plants during droughts.
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“Heat-damaged leaves appear progressively reddish or brownish in color and become dry and brittle to the touch,” Kratsch said.

Take care of plants while you are away

If you’re away from home for several days, try moving potted plants to a sheltered, shaded area if you don’t have someone to water them while you’re away, Lang said.

During dry conditions, it is also important to eliminate all competition from desired plants, which may include weeds; weak, diseased or stressed plants that are past their prime; and annuals that can be easily replaced, Bradley said. Also, don’t encourage plant growth by fertilizing or pruning: “Growth taxes the entire plant and new growth is vulnerable,” he said.

Fertilizing drought-stressed trees and shrubs often encourages more foliage at the expense of root growth, according to Pandian, who also recommended avoiding unnecessary repotting.

When it comes to grass, don’t worry too much if it begins to go dormant, noticeable by a brown color, in excessive summer heat. Most grasses can survive two to three weeks of dormancy and will green up again as temperatures cool.

“Small areas that don’t recover can be overseeded in the fall (unless there’s still a drought) or in early spring,” Kratsch said. “An alternative is to learn to accept a less than perfect lawn (as Mother Nature intended). Don’t fertilize lawns or other landscape plants during drought.

“For upcoming drought years, consider replacing unneeded grass areas with plants that can better handle hot and water-scarce conditions.”

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