Plants Require Extra Care In Summer Heat

From The Fresno Bee, June 10, 2010; by Elinor Teague:

Our high summer temperatures have arrived, and we will need to adjust some for our gardening routines to help our plants adjust and survive several months of hot weather.

Most gardens are looking the best I've ever seen.

The longer, cooler spring with no major hot spells has allowed an extra few weeks for newly planted trees and bushes, transplants of annuals and summer vegetables, newly planted trees and bushes, and existing perennials to establish or extend root systems.

Plantings that were stunted during the previous three years of drought and heat now are vigorously producing fruit and flowers.

It seems as though every spring and summer-blooming plant was in full flower a couple of weeks ago.

Deadheading the first crop of spent blossoms is a big chore this year, but essential to encouraging rebloom. When deadheading, cut off as few leaves as possible. Leaves produce food for the plants and also can provide a little extra shade.

For the same reason, adjust lawn mower blades to cut off only a third of the blades' length since taller grass blades shade the roots.

Shear back rapidly-growing hedges lightly but frequently. Scalping hedges and lawns in summer can cause sunburn damage.

The second crop of flowers on summer-bloomers will not be as plentiful as the first.

High temperatures in June will begin to stress plants an slow flowering production; petals will be thinner, colors will dull a but, and fragrance will not be as strong.

This is a normal reaction to heat. Keep this in mind when fertilizing and geed lightly in June. Use a lower-nitrogen (10% or less) at half the recommended rate to avoid a spurt of tender new green growth that will attract insects such as whiteflies, aphids and mealybugs.

In July and early August, when daytime temperatures regularly exceed 95 degrees, plants enter a state of semidormancy. I forgo fertilizing anything when the weather is really hot.

Wilting is the most obvious sign that plants need water, but the first sign of drought stress actually is a change in the color and texture of leaves and grass blades. Drought-stressed leaves will change from brighter green to a duller, grayish-green. Some leaves, especially on citrus, will turn up or close a little. Grass blades will show a blue shade and footprints will remain visible on hte lasn for a longer time.

Even a little stress from underwatering and overfertilizion in summer can stress plants and stressed plants attract pest insects. Feeding lightly (if at all) and monitoring irrigation systems and adjusting watering times as needed during our hot summers can prevent a lot of insect damage and reduce the use of pesticides.