As rapid growers—averaging about 2 feet of growth per year—larger varieties of hydrangeas can reach up to 15 feet tall. Applicable in growing zones 3 to 9, hydrangeas are a low maintenance plant that will return year after year with proper care.
Is Hydrangea a perennial? Yes, Hydrangeas are perennials: they go dormant in winter and come back in the spring on their own, assuming you've planted varieties suited for your Zone. Gardeners in northern Zones must take care to choose winter-hardy varieties.
Snow cover not only provides insulation, but also a water source. If you live in an area that doesn't have snow — or doesn't get snow — make sure you've got enough rain or water to get them through. Also, be sure the base of the hydrangea is covered with wood chips, oak leaves, pine straw or other mulch.
If you don't prune hydrangeas then they can eventually resemble a tangled mass of woody stems, and the flowers will become smaller and less showy.
Hydrangeas that bloom on new wood can be safely pruned in late fall once the plants have gone dormant or in early spring. Next year's flower buds won't be formed until late spring the same year they bloom, so there is no risk of removing the buds if you prune in fall or spring.
Keep Them Cozy. 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.
In late winter or early spring, these shrubs can be cut all the way back to the ground. Smooth hydrangeas will produce much larger blooms if pruned hard like this each year, but many gardeners opt for smaller blooms on sturdier stems.
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.
Hydrangeas are long-lived shrubs, sometimes living for up to 50 years if properly cared for. They enjoy morning sun but afternoon shade, and they need frequent watering during the growing season. Prune them in the fall after the blooms fade so they can grow on strong stems the following summer.
Where to plant hydrangeas. Hydrangeas do best in moist, well-drained soil and dappled shade – not too sunny and not too shady. Avoid south-facing positions, especially if the soil is very dry. For a very shaded spot, such as a north-facing wall, grow the climbing hydrangea Hydrangea anomala subsp.
Many customers ask why their hydrangeas aren't blooming. The primary reasons hydrangeas don't bloom are incorrect pruning, bud damage due to winter and/or early spring weather, location and too much fertilizer.
Most common hydrangeas prefer a partial sun location - ideally receiving sun in the morning hours and shade in the afternoon. The reblooming Endless Summer® Hydrangea series prefers part shade.
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.
While some plants bloom on new growth, others primarily set flower buds on old wood. Regardless, it is best to wait to prune all hydrangeas until spring. In the fall, hydrangeas (and all trees and shrubs) are in the process of going dormant. They do not produce very much new growth until the following spring.
Mophead hydrangeas look lovely in the fall when their blue, purple and pink flowers contrast with the fall foliage. Brown flowers can be snipped off if they annoy you, but you don't have to remove them.
Look at the foliage to identify your type of hydrangea. Mountain hydrangea foliage has serrated edges that are often tinted maroon at the edges. The round hydrangea flower form comes in what is called a mophead or lacecap version. The lacecap flower has outer petals that surround the pollen capsules in the center.
Hydrangeas Are Toxic To Dogs
"The toxic component of the hydrangea plant is a cyanogenic glycoside." Chewing plants with this compound causes cyanide to be released. The leaves, buds, flowers, and bark all contain the toxin, so if your dog munches any part of your hydrangeas, he could get sick.
Frigid winter temperatures, as well as winter winds, can cause winter kill on hydrangeas. The low winter temperatures can kill the plant, or they might die because of drying out caused by winds.
The Bottom Line. If extreme cold weather has damaged your Hydrangeas, they will most likely recover. These plants are hardy, and though they may not rebloom this year, as long as you prune back the damage done, you should start to see its beautiful flowers the following spring.
Cut back any clearly dead branches, which are brittle and snap off easily. This can be done in the fall or any time you see a dead branch. To reduce the size of a hydrangea that blooms on new wood, cut off about one-third of each stem in late fall or early spring before it begins to leaf out.
Bottom-line: Panicle-type hydrangeas should be pruned in late winter or early spring. While they could be pruned in fall, we highly advise waiting until late winter/early spring to reduce risk of injury.
They don't form a central taproot like rhododendrons and shrubs. Instead, they grow in a loose, spreading mass of fibers often referred to as a root ball. The vast majority of a Hydrangea's roots will stay within the top six inches or so of soil. However, they do tend to spread quite a bit in the horizontal direction.