I’m sick of this summer heat. Imagine how it feels if you are a shrub or a tree and are literally rooted in place.
Our recent winter with little rainfall left our plants with no reserves to cope with the summer heat – and the summer has been long and hot! Even as fall approaches, we must continue to monitor our plants for water stress.
Symptoms of too little or too much water can be very similar. Acute water deficit occurs when water loss from leaves increases, during conditions of extreme heat or wind, or when the water supply suddenly decreases. Many plants will wilt at the hottest time of the day, but will recover overnight if the problem does not persist.
A chronic water deficit causes slow growth or stops growth altogether. The color of the leaves can change and deciduous trees can drop their leaves prematurely. Prolonged water stress causes shoot and branch dieback. Plants suffering from chronic water stress have less resistance to pests, which leads to injury from insects or disease. Leafy plants have a permanent wilting point, beyond which they cannot be regenerated.
Potted plants and plants in small areas limited by concrete have a reduced soil volume. This limits the water available in the root zone. Environmental factors, such as high light intensity, wind, temperature and relative humidity determine the evaporation potential of the plant location. Plants should be checked daily for their water status. A quick and easy method is a moisture meter. The probes are driven into the ground and record from dry to wet. The counter can be found at home improvement stores for around $ 12-15. They are especially handy with plants placed in a saucer to prevent water from entering the patio. The soil on top may feel dry to the touch, but the meter will detect if the pot is not draining and if the roots are in fact in the water. If the plant is in water saturated soil, the roots cannot take up oxygen, nutrients, or water, and the plant will die.
Spread mulch on the ground around trees and shrubs to keep moisture and heat away from the roots. Mulch should be kept away from the crown of the plant to avoid fungal diseases. If the plant is on a drip irrigation system, transmitters should be checked regularly for clogging, displacement by lawn equipment, damage from ground squirrels, or improper pruning of the plant. As the plant or tree grows, additional water will be needed.
Using a hose timer will save water when using a sprinkler to water a stressed plant. An alternative is to use the kitchen timer to avoid forgetting that the hose is leaking and wasting water. Fall is the best time to plant many perennials, but they will need more water to establish themselves when the temperature is still high.
Brown spots on the lawn? First, check the timer and sprinkler system, power outages due to thunderstorms may require resetting the timer. Then run the system manually to check that the sprinkler heads are not damaged or clogged, the amount of water applied, and the coverage of each sprinkler head. A canister tests tuna cans on the lawn, runs the sprinkler for 20 minutes, then measures the water in each can – is a quick check of sprinkler performance and coverage.
Continue mowing the lawn with the mower set high. The taller blades of grass shade the roots of the plant, retain moisture, and prevent the sun from reaching the weed seeds in the soil. Irrigate the lawn deeply, not in small amounts daily. Shallow irrigation encourages weeds, especially crabgrass which thrives in the summer heat.
Is summer time to fertilize?
Check the label on the fertilizer for the optimum temperature for the application. Usually it is less than 85 degrees, otherwise the fertilizer can burn the plant. It will also encourage the growth of new plants, which is more stressful for a plant that copes with the heat.
Cross your fingers that fall arrives; people and plants will feel relief from the heat.