You set out wooden stakes around the plant(s) and then drape the shade cloth over the plant(s) using the stakes for support. This is an identical technique used during the winter months for frost protection. The covering should be set up when the weather forecast calls for hot temperatures over 95 degrees.
Most hydrangeas prefer only morning sun. Yet one type of hydrangea can soak up the sun all day: the panicle hydrangea. While they can stand the sun, these do just fine in partial shade, too.
Mature flowers with a slightly papery feel will hold up best. Immediately place the stems, cut at an angle, in a bucket of water. Arrange them right away, or store in a cool, dark place (such as a garage) for up to two days.
Apply mulch, preferably a reflective mulch such as dry grass clippings. The first line of defense against hot weather and the windy conditions that can dry surface soil is to apply a liberal layer of mulch around the plants. This protects the soil from direct sun exposure, keeping it moist at the surface.
During really hot weather, water your vegetables at least two to three times a week. Watering the garden deeply is critical. The water must go down, down, down to encourage deep roots and get away from the hot soil surface.
Shade Cloth
Garden fabric creates excellent sun protection for plants. Most of the fabric is light enough that it can be draped directly over plants. For plants that may be a little more delicate, such as tomatoes, you can use support hoops to keep the fabric off of the plants.
Whether or not hydrangeas need protection depends on how cold the winter temperatures drop. If the air temperature doesn't go below 0 degrees (zone 7) there is no need for winter protection. In colder climates, wrap or completely cover marginally hardy hydrangeas.
Hydrangeas need more water than most garden plants and will begin to wilt quickly without it. To ensure that Hydrangeas thrive, water deeply two to three times a week in the summer. Be sure to water in the morning or evening so that water does not evaporate as quickly as it would during the heat of the day.
Hydrangeas are amazingly resilient, she says. If they wilt in the heat of a summer afternoon, they will likely perk up by the next morning. But don't let them suffer too often or the cell structure will collapse and the leaves may not come back until fall rain or even next spring.
Just like Hydrangeas getting too much sun, a Hydrangea getting too much sun may develop wilting and yellowing leaves, even some brown spots.
"Hydrangeas can look stressed in extreme heat but will perk up when temperatures drop," says Clay. "If the plant is looking a bit sad even with cooler temperatures, it likely needs water."
The Endless Summer hydrangea thrives in partial shade and needs well-drained soil with consistent moisture. It does need some sunlight for photosynthesis and flowering potential, but overly hot direct sunlight can scorch the leaves.
Some gardeners report success in turning their hydrangeas blue by applying coffee grounds to the soil. The coffee grounds make the soil more acidic, allowing the hydrangea to more easily absorb aluminum. In addition, fruit peels, lawn clippings, peat moss and pine needles, are thought to have a similar effect.
It's best to start adding coffee grounds to the soil months before the blooming season begins, ideally in the late fall. You can repeat the process with your typical fertilizing schedule.
Hydrangea Heat Stress
Heat and drought stress can cause the stomata of your hydrangea plant to remain open as they try to absorb water vapor from the environment that they are in. Unfortunately, this causes water to be lost more than it is gained which over time translates into wilting.
"In this heat, hydrangeas—especially the blue/pink bigleaf or "French" hydrangeas—will transpire water vapor from their leaves faster than their roots can replace the water," says Doggett. "This causes the stems, leaves, and blooms to wilt or droop by late afternoon."
Sun helps many varieties bloom, but full sun is rarely required. Bigleaf hydrangeas, which are the variety most people think of when they think of these popular shrubs, can take full sun in cooler areas (zones 4 to 6). But in warmer areas (zones 7 to 9), they do best with morning sun and afternoon shade.
Prune back stems to just above a fat bud — called a heading cut — in fall, late winter or spring. These plants have conical-shaped flower heads. I recommend leaving the dry, tan flower heads on the plant to provide some winter interest in your landscape, so I wait to prune these until late winter or spring.
Appearance. The Endless Summer Hydrangea is a shrub, growing in a rounded shape. Its dark green leaves range from 4-8 inches long, and its stunning blooms are showy mopheads nearly 8-10 inches in diameter.
Most plants suffer when the weather turns hot enough for a certain period of time. It causes irreversible damage by way of plant function or development. This isn't merely droopy leaves in the heat of the afternoon; it's things like stunted growth, leaf drop, leaf scald, failure to flower, or failure to produce seeds.
Some plants died and others were fried by the record-breaking temperatures. Even some that look extremely bad, like rhododendrons and hydrangeas, can bounce back. Burned leaves don't necessarily equal a dead plant, so patience and observation is needed.
Most plants grow best in temperatures ranging from 59°–86°F. When temperatures above 90°F are sustained for long periods, plant growth is slowed, and some plants begin to show signs of stress.
Be Consistent
You should check the moisture level around the base of your plants. Determine the watering schedule you need to keep in order to maintain the right level of moisture. Watering every day or every two days doesn't matter nearly as much as consistent watering. Make a schedule and stick to it.