Oh, wow! So many choices. Mopheads, Lacecaps, Hortensias, Smooth, Oakleafs—lots and lots of cultivars! Expect to see new options every season as the popularity for Hydrangeas continues to trend upward.
Hydrangeas have big flowers that look beautiful in flower arrangements. Many have their peak bloom in June, which makes them a favorite for weddings. They grow in mild shade. There are some with amazing blue blooms. There have been many wonderful cultivars, and it is impossible to learn them all.
Let’s focus on the landscape qualities of Hydrangeas. They bloom when daylilies bloom, so they make a nice combination planting in the garden. The coarse textured leaves make an exciting contrast with little-leaved Holly species. The mounded forms make an exciting contrast with pyramidal forms and as an understory plant for large trees. Because they are deciduous, they loose their big, blousy leaves to expose some rather ragged stems in the winter. It’s best to locate them away from areas which receive close scrutiny in the dormant season. Hydrangeas take time off from being beautiful after frost through early spring.
You can easily dry Hydrangea flowers for decoration. Place flower stems in about an inch of water and leave them there until they dry completely. Do not replace evaporated water. The result is a colorful, dried version for winter wreaths. Another method of drying Hydrangeas, used in the south, is to place a bouquet of blooms in the hot trunk of the car on a blistering, sunny day to gently bake them into dried specimens.
It’s best not to prune the cultivars which bloom on previous-year’s growth. The best ‘Nikko Blue’ Hydrangeas are neglected clumps abandoned on the east side of an old mill town home. For cultivars blooming on new wood, you can prune individual stems back by one third shortly before new leaf buds emerge to encourage dense growth and robust blooms.
• The Bigleaf Hydrangea (Hydrangea macrophylla) is the favorite of brides and grandmothers. ‘Nikko Blue’ is a reliable, old, blue favorite. Zone 5b. ‘Endless Summer’ is a cultivar that blooms on new wood and will probably replace it. ‘Mme. Emile Mouillere’ is almost a white blue. The leaves on this shrub are big, of course. They are also thin. When stressed by drought, they tend to wilt dramatically, but recover by morning. Expect growth to be about four to six feet. ‘Variegata’ is a pretty lacecap cultivar.
The leaves are big and full of water. In summer they can lose turgidity and look wilted, especially in the afternoon heat. Locating Hydrangeas where they receive morning sun helps them thrive and be floriferous. They may thrive with too much shade or hot, western sun, but they won't flower well.
Bigleaf Hydrangea flower color will be blue unless the pH is raised to a certain level. The more acid the soil, the more aluminum, and the aluminum is what causes the blue color. You can see variations in gardens depending on who puts lime in the soil, how much construction debris has been left in the area, or if chlorine bleach has been spilled nearby. Sometimes there is variation on a single plant. It’s fun to note the differences.
Bigleaf Hydrangeas are called French Hydrangeas by older southerners. The cultivars grown in greenhouses and sold in florist shops may not be hardy enough to withstand outdoor freezes.
• The Smooth Hydrangea (Hydrangea arborescens ‘Annabelle’) is a native. This cultivar, has white corymbs so huge they weigh down the limbs. They love moist, well-drained, fertile soil. In a good soil situation it can be floppy, but not so much in a more typical garden situation with un-amended soil. It stays about three feet tall. This is an amazing plant that carries the flower display with an attitude that deserves respect.
• The Oakleaf Hydrangea (Hydrangea quercifolia) is a three-season performer. The long white flower clusters are a mix of sterile and fertile forms that give them a lacey quality. The fall color is a pretty burnt red-burgundy. Zone 5. The stems peel a nice cinnamon brown color.
The leaves can be almost as spectacular as the blooms for the Oakleaf species. The fall color ranges from a deep brown purple to glowing-embers red.
• I like ‘Snow Queen’ better than ‘Snowflake’, two of many improved cultivars. Snow Queen looks more natural and the blooms are not so heavy where they pull the branches down. If you are looking for something to provide foliage texture contrast, this is it. It has an attractive, coarse look. The leaves are very interesting.
• ‘Sikes Dwarf’ and ‘Pee Wee’ stay under three feet.
PeeGee Hydrangea (Hydrangea paniculata 'Grandiflora')
PeeGee Hydrangeas are used in northern landscapes in a similar manner as multi-stem, tree-formed Crapemyrtles are use in the south. They don’t bloom until late summer, but once they do the large, pyramidal clusters refuse to go away. They turn from white to pinkish, to brown. The small tree/large shrub grows to twenty feet tall. The shrub can handle full sun. It is one of the few Hydrangeas that can. Zone 4.
The brown, dried-out clusters continue to cling to the stems well through the winter. The nursery marketers call this color “parchment.” A lot of people think of it as ugly brown. It’s a perfect shrub for Miss Haversham’s garden. The brown clusters are not attractive, but they have a certain winter interest similar to dried out perennials left out in the snow. By January, they look quite shabby. Take the time to clip each spent cluster if you can reach them. Or, you can pick the blooms on a dry, late summer afternoon when their color is still good and use them in long-lasting dried flower arrangements!
The stems and trunks remain fairly small, so the blooms tend to pull the canes almost down to the ground on a healthy specimen. It helps to cut back a few canes each year to rejuvenate the shrub. If not, the entire plant tends to deteriorate and decline with time. Don’t prune in the fall! I like to wait until early spring before new leaves sprout, and cut each stem back by at least one-third its total length. It forces fresh growth and healthier-looking blooms. It delays the bloom past the dog days of summer, so they last longer.
There are new cultivars attempting to improve on the old-fashioned, much-used ‘Grandiflora’. Some have pinkish or lime-colored blooms and others have more lacey blooms.
• My favorite is ‘Brussels Lace’. It doesn’t have the gaudy, giant blooms of the other improved forms.
• Similar to ‘Brussels Lace’ is ‘Tardiva’, a particularly drought-tolerant cultivar with both sterile and fertile blooms.
• ‘Pink Diamond’ has pinkish blooms.
• ‘Chantilly Lace’ turns pinkish with time.
Dwarf PeeGee Hydrangeas can handle full sun. The stems and trunks remain fairly small, so the blooms tend to pull the canes almost down to the ground on a healthy specimen. It helps to cut back a few canes each year to rejuvenate the shrub. If not, it tends to deteriorate and decline with time. If you cut back all the stems by one third in early spring, you can generate healthy growth and a late summer, early fall bloom when little else is blooming. Zone 3.
• ‘Limelight’ grows to six feet or more. It is a dwarf PeeGee, with lime green flowers that age to burgundy. This cultivar has saved the PeeGee from obscurity. People hated the ugly, dried brown flower clusters that stayed on the original PeeGee all winter. ‘Limelight’ solves that problem. The panicles go brown in a much more attractive way.
• ‘Vanilla Strawberry’ grows to seven feet tall, with white flowers that mature to pink.
The word origin of Hydrangea is Greek. It means water vessel. Relative to other shrubs in the landscape, they require ample, but not too much, water. Other than that, they are un-demanding and productive, colorful shrubs.