Inadequate amounts of water can stress plants and cause a multitude of problems. Usually, the oldest leaves are the first to show symptoms, yellowing, drying and falling off the plant. During prolonged periods of drought, twigs and branches of trees and shrubs can suffer dieback. Drought conditions can even cause root damage, which generally leads to the eventual death of the plant.
Of course the longer a drought lasts, the more damage is done to the plants. Insufficient water at the start of the growing season can cause the most damage of all because the plants are actively growing and preparing themselves for the summer growing season.
When drought and water restrictions are in effect, all we can do is wait it out. Hopefully, our plants were healthy, vigorous and mulched beforehand. Once the drought is over, it's time to assess the damage and take corrective action to get our plants back into shape.
Certainly, we want to resume regular watering of our plants as soon as practical. It's tempting to want to give drought-stressed plants as much water as they can handle, but it is possible to overdo it. You want to ease your plants back into health rather than drown them. When you resume watering, keep the soil moist, but not wet. Roots need oxygen as much as they need water and keeping the soil saturated will suffocate the roots and lead to more stress.
There's not much we can do about too much rainfall, but we can control the hose and sprinkler. Most plants need one inch of water per week or about one gallon per square foot. If the plants are growing in sandy, quick-draining soil, were recently planted and have immature root systems, or have damaged roots, they will need to be watered a couple of times a week to make sure they are receiving and taking up sufficient water.
Prune Back Plants
Plants seem to know when they are threatened and need to reinvigorate themselves.
During a long drought, it can sometimes help to prune otherwise healthy plants back by about 1/3 to lessen the plant's need for water. Use your judgment as to which plants need this extra help and avoid cutting back trees and shrubs. They need their canopies to prevent scorching and burning and pruning them back would just cause more stress.
After the drought period ends, if the tops of your plants have suffered severe browning and dieback, prune them back to about six inches from the ground. In many cases, you might already see new growth starting at the base of the plant.
If the plant has dead or dying branches, remove them. The dead branches won't recover and they make good hiding places for pests and entry points for disease.
Use Fertilizer With Care
Don't fertilize your plants during a drought. Without adequate water, fertilizer would either be wasted or would just cause more stress. Once a drought ends, a slow-release fertilizer is the best option. It will be available as the plant recovers and will help ease it back into vigor. Choose a fertilizer with a high percentage of phosphorus, rather than one high in nitrogen. The phosphorous will aid in repairing the root system, where nitrogen would encourage rapid leaf growth that could compound problems
Synthetic fertilizers containing salt are the worst option after drought and should be avoided entirely during and after drought. The salt in the soil can damage the plant's roots and intensify drought damage.
Catch Secondary Problems Early
Drought-stressed plants are targets for pests and diseases that will further weaken your plants. While you should be on the lookout for problems throughout the season, keep an especially keen eye during droughts. Catch problems early. You might not be able to cure the problem, but you can stop it from spreading. In some cases, you might need to do some pruning and perhaps have to remove the plant entirely if the problem is severe.
Once your plants have been well watered and possibly fed, make sure they have a three- to four-inch layer of mulch around the drip line. Organic mulches decompose during the growing season and by mid-to-late summer, they might have almost disappeared. Keep those stressed roots cool and moist by replacing the mulch as soon as you can.
Drought Damage Prevention
- Choose drought-tolerant plants: Some plants handle drought and low moisture better than others. Choose drought-tolerant plants and create a water-wise garden. If you must have plants that require more water than average, group them together so you can provide extra water to just that small area.
- Organic matter: Continually add compost and other organic matter to your soil to improve its ability to retain moisture.
- Weed: Weeds compete with garden plants for water and nutrients, and weeds usually win that battle. Remove weeds as soon as you see them to prevent them from robbing moisture and nutrition from your desirable plants.
- Rain barrels: Now is the time to attach a rain barrel—or two—to your downspouts. It's amazing how much rooftop water can be collected after just one rainfall and how glad you'll be to have it during the next dry spell.
“Long-Term Drought Effects on Trees and Shrubs.” Center for Agriculture, Food, and the Environment, 6 Mar. 2015, https://ag.umass.edu/landscape/fact-sheets/long-term-drought-effects-on-trees-shrubs
D“Dakota Gardener: The Art and Science of Watering Your Plants.” Plone Site, https://www.ag.ndsu.edu/news/columns/dakota-gardener/dakota-gardener-the-art-and-science-of-watering-your-plants