The exact preferences of your hydrangea will depend on which variety it is. While Oakleaf, Climbing, and Mophead Hydrangeas will all take between three to six hours of direct sun, other varieties (like Mountain, Panicle, and Smooth Hydrangeas) prefer more than that.
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 grow best in full sun (more than 6 hours sun) to part sun (4-6 hours sun). With that being said, all hydrangeas can handle some shade, but the timing and type of shade are important to consider. They can be in full shade during the hottest part of the day, as long as they are getting some morning sun.
Hydrangeas grow well in partial shade, but too much of it and they won't flower. While these plants traditionally grow wild in the understory of forests, they still receive some dappled sun in their natural habitat. If yours is planted in a spot where it isn't receiving enough sun, you won't see blossoms.
Most common hydrangeas prefer a partial sun location - ideally receiving sun in the morning hours and shade in the afternoon.
TOO MUCH SUN
Conversely, too much direct sun may stress hydrangea plants, which can force them to conserve energy by not forming flowers.
Hydrangea flowers can wilt due to too much sun or insufficient watering. Hydrangea flowers can wilt when they are getting too much sun or not enough water. Aside from Hydrangea paniculata which loves full sun, most hydrangeas only desire morning sun. If they are left in the heat for too long they will begin to wilt.
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.
Hydrangea macrophyllas, commonly known as 'Big Leaf Hydrangeas', are ideal for almost any shade setting & are prized for its large flowers and dense foliage.
Shade-Loving Hydrangeas
Annabelle, Invincibelle, and Incrediball are three hydrangeas that perform well in mostly shaded sites.
Hydrangeas can be grown in full sun but too much direct sunlight, especially during the afternoon hours when the sun is most intense, can cause wilt. When exposed to excessive sun, the plant's internal temperature increases, which causes the leaves to transpire and leads to moisture loss in the cells.
Deep weekly watering is usually enough (if you don't get enough rain). Although you may need to water more often in hot, dry weather. Water hydrangeas deeply and regularly in the first growing season to encourage an extensive root system.
Endless Summer hydrangeas grow best in partial sun. A location that receives morning sun and dappled afternoon shade is ideal. If these hydrangeas are planted in full sun, conditions might be too hot and intense for the plants to produce blooms. Planting in too much shade can result in weak stems and fewer blooms.
4. All hydrangeas will turn brown if they wilt too many times in hot weather. Water these shrubs deeply every few days in the heat of the summer (note that hand watering isn't deep enough) and mulch around plants to hold moisture in the soil longer.
So, when is the best time to plant hydrangeas? Aim for late spring, well after any danger of frost has passed, or early fall, when night temperatures usher in cooler air. If you garden in a region where the ground freezes, get plants into the ground at least six weeks prior to fall's first killing frost.
Unless the shrubs are planted in a raised bed that sits above the root system of trees, avoid planting hydrangeas directly beneath trees where they must compete for water and nutrition. The shrubs grow best in soil that contains plenty of organic material and good drainage.
Hydrangea paniculata is one of the hardiest species; it thrives in Zones 4-8.
All they need is well-drained soil, some water and a little bit of shade during hot summer days. Find out even more about hydrangea care in our Complete Hydrangea Guide! Oakleaf varieties are the easiest type of hydrangeas for beginners to grow.
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."
The combination of too much sun and not enough water is a common cause of hydrangea droop, making it a great place to start when your plants are feeling unwell. Check the moisture level of your hydrangea at a point 1 to 2 inches (2.5-5 cm.) below the surface of the soil with your finger.
Keep good air space between the plants; don't crowd them together or against other plants. Don't give bigleaf hydrangeas too much love; if they're too comfortable (water, fertilizer, etc.), they may devote all their foliage to leaves instead of blooms.
When you deadhead hydrangeas, you aren't harming the plants at all. Removing the spent blooms triggers flowering shrubs to stop producing seeds and instead put their energy toward root and foliage development. This makes plants stronger and healthier, so by deadheading, you'll be doing your hydrangeas a favor.
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.
When a hydrangea receives too much water, its roots begin to rot. It can be difficult to tell whether the roots are rotting just by looking at it (although the other signs mentioned here are usually symptoms of root rot), but you may notice an unpleasant, rotting odor near the plant if root rot has set in.