Protecting Plants From Heat And Drought

Many regions of the U.S. suffer extreme heat in the summer. Whether it’s due to climate change or not, plants suffer stress under these conditions. Often plants take on characteristics that provide signs that they are stressed due to heat. If you know the signs, then you can take action to provide relief.

Extreme heat can cause plants to stress.
(Luca Castellazzi at

Signs Of Plant Stress

Extreme heat and drought negatively impact photosynthesis and other plant functions.

Photosynthesis is a process in which plants convert sunlight into chemical energy to fuel themselves. The energy is synthesized from water and carbon dioxide and is stored in carbohydrate molecules within the plant. Photosynthesis is an essential activity for the planet because it produces oxygen. When the plant breaths, it emits the oxygen back into the atmosphere while it retains and conserves carbon dioxide and hydrogen that is converted into energy and glucose that ensures the plant’s healthy development and assists it to grow. The glucose is stored in the fruits, roots, and leaves of a plant for later use.

The signs that represent stress due to extreme heat and drought conditions include:

  • Wilting leaves and stems.
  • Dropped leaves, blossoms, or immature fruit.
  • Yellow or a burnt appearance along the margins of the leaves.
  • Slow or stunted growth.
  • Bolting.
  • Blossom-end rot.

Bolting is when the plant grows a tall flower stalk in a very short period of time.

Be aware that some of these symptoms may have more than one cause. So it is up to you to make the proper call.

Plants Protect Themselves From Heat And Drought

Plants can take care of themselves during extreme heat and drought for a short period of time during flowering or fruiting. In the case of fruiting, plants do recover from heat and drought and look fine until the fruit fails to mature. The fruit is stunted and develops split skins or shows other symptoms. After plants experience that first event of extreme heat or water deprivation it is nearly impossible for them to recover another bout with heat and drought.

Water To The Rescue

When plants don’t get sufficient amounts of water, they can’t perform photosynthesis efficiently and start showing signs of stress. This is when it is essential to provide the plant with water. It is recommended that you add 1-inch of water to your garden slowly once a week. The plants benefit most from the watering when 1-inch of surface water is within easy reach of the roots over a square foot area. The amount of water comes to a bit more than half a gallon. It should be distributed around the base of each plant.

If your plants are not receiving adequate amounts of water either via a soaking rain or watering, you will probably start seeing signs of trouble. Of course, it is always better to prevent the problem if you can.

Different plants have different water needs. So always check the environmental preferences of the plants you include in your garden. In addition, take soil composition and other important factors into account.

How To Minimize Heat And Drought Stress

The best way to minimize or even prevent drought and heat stress on your plants during a sizzling summer is to plan ahead. Needless to say, this doesn’t help when your plants are in distress now. However, it can prevent issues next year.

Your plan should include these strategies:

• Choose the right plants. The plants you choose for your garden should be drought and heat resistant and a native variety.

• Use plenty of soil amendments. The amendments should be formulated to improve fertility and increase water retention. Ideal soil is loamy and includes a mixture of clay, sand and decomposing organic materials. It is these materials that will provide nutrients.

• Use primed seeds. Primed seeds are ideal for drought regions. These seeds have been partially germinated through limited hydration and then dried. This puts the seeds in a state of suspended animation. So when rehydrated, they germinate quickly. Thus making them ideal in drought regions.

• Increase spacing between plants. Allowing more space between plants reduces competition for water and other nutrients and also improves airflow.

• Afternoon shade. Building walls can provide shade or you can relocate plants to an area that is shaded by your home.

• Layer your plants. A layered scheme including taller plants that throw shade over smaller plants would work nicely to combat the heat.

• Smart water management. Include a timed, drip irrigation system for your garden or a watering harvesting system like rain barrels.

• Sow Seeds earlier. This will change the growing season so that the plants mature before the higher temperatures arrive. Keep in mind that this strategy is limited by the earliest frost-free date for planting in your area.

• Sow seeds directly into the garden. It is risky and probably something you are not used to doing. But it can offer dividends. The idea is that the directly sown seedlings will adapt to the actual environmental conditions and thus be better prepared to survive heat or drought stress later.

• Water in morning or evening. There is less water evaporation during those times and it is easier for you to evaluate the amount of water available for your plants.

• Practice deep watering. Train your plants with deep watering. Water at depths of an inch trains the roots of the plant to burrow down where there is adequate moisture on dry days. In addition, the soil is cooler at deeper depth. Heat stress isn’t just caused by air temperature. Increased soil temperature also plays a role.

• Add mulch. Mulch improves the soil’s ability to retain moisture and remain cooler during extremely hot days. It also reduces stress on plants with shallow root systems and eliminates weeds that compete with plants for water. Use organic mulch like dried leaves or straw. It assists the soil in retaining water.

• Use shade cloth. The cloth offers partial protection for plants during the hottest periods of a day. Shade cloth is made of polypropylene or polyethylene. You can use a simple wood or PVC frame to secure it. Another benefit is that it helps extend the fall growing season.

• Prevent soil from drying out. You don’t want the soil to become too dry because it becomes porous and its ability to retain water is reduced.

• Use a plant growth regulator. A plant growth regulator is a natural or synthetic chemical that is sprayed or applied to a seed or plant to alter its characteristics including increase insect and disease resistance or increasing root strength. There are five kinds of plant growth regulators –- auxins, cytokinins, gibberellins, abscisic acid, and ethylene. A plant growth regulator that contains abscisic acid assists plants to control their responses to drought stress.


About Robert Janis

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