Most hydrangeas prefer only morning sun. Yet one type of hydrangea can soak up the sun all day: the
Panicle hydrangeas can handle hot sun
While they are drought tolerant and stand up to heat, I still like to provide shade during the hottest part of the day. And just because they are drought tolerant doesn't mean you should let them wilt. As with all hydrangeas, plants will thrive with regular irrigation.
Bigleaf hydrangeas, also known as hydrangea macrophylla, vary especially with some of the newer cultivars being bred to better tolerate heat and sun, but most of these including the mopheads and lacecaps prefer some shade, especially during the afternoon.
Just like Hydrangeas getting too much sun, a Hydrangea getting too much sun may develop wilting and yellowing leaves, even some brown spots.
Provide Some Shade
Most varieties of hydrangea prefer afternoon shade. If you think your hydrangea can benefit from a break from the sun you can purchase shade cloth online or from your local garden center. But honestly using a beach umbrella or an old bed sheet will work just as well.
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.
Many people think that you need a shady garden in order to grow hydrangeas. While that is true for some varieties, some hydrangeas thrive in sunny spots and even need full sun to develop into the fullest plants and the brightest blooms.
While several species of hydrangeas thrive in shade, panicle hydrangeas (Hydrangea paniculata) are the best for growing in full sun. These summer-blooming shrubs produce large clusters of white flowers for several weeks. The showy blooms fade to shades of pink or red before drying to beige.
TOO MUCH SUN
Conversely, too much direct sun may stress hydrangea plants, which can force them to conserve energy by not forming flowers.
The further north your garden is located, the more sunlight your hydrangeas need. An average rule of thumb is six hours of sunlight per day. However, hydrangeas growing in the south can perform on only three hours of sunlight.
"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."
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.
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.
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. Plus, panicle hydrangeas are the hardiest hydrangeas.
The hydrangea should be watered thoroughly at least 3 times a week. Always water the plant all the way around the container, not just in one place. Water should come out the bottom of the pot. Never let it sit in water which will cause the roots to rot away.
If You're Looking For Heat-Tolerant Hydrangeas
Some of the most popular heat-tolerant varieties include the bigleaf hydrangeas (Hydrangea macrophylla) in the Let's Dance series and smooth hydrangeas (Hydrangea arborescens) in the Incrediball series.
Endless Summer hydrangeas should be planted in a place that receives morning sun and dappled afternoon shade. "The amount of sun they can tolerate depends on the zone," says Mcenaney. "Endless Summer hydrangeas that are planted in zone 4 can tolerate more afternoon sun than those planted in zone 9."
Timing depends on the type of hydrangea you have, and there are many. First, know hydrangeas do not have to be pruned — unless the shrub has grown too large for its space or unruly and needs a little shaping up. Otherwise, you can simply clean up the plant by removing dead branches and deadheading spent blooms.
Stephen Sullivan, the editor at Plant Native, says: 'Among the different types of hydrangeas, the Oakleaf hydrangea (Hydrangea quercifolia) and the Panicle hydrangea (Hydrangea paniculata) tend to be more resilient in dry conditions compared to the Bigleaf hydrangea (Hydrangea macrophylla).
The hardiness zones for H. macrophylla are 6 to 9. Effectively, a hydrangea should be able to sustain a temperature of minus-10 degrees. But in the real world, temperatures as low as 12 degrees — and late fall or early spring freezes — may reduce the flowering capability of this hydrangea.
"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."