Hydrangeas flower year after year with proper care, placement, feeding
For those lucky enough to coax flowers from their hydrangeas, the pretty blooms are all fading to green, soft pink or brown, depending on variety, as the season winds down.
Growing the shrub and getting blooms can be confusing for gardeners as there are six main types, and each one has different needs for flowering.
One thing is for sure: The No. 1 question from gardeners is, “Why doesn't my hydrangea bloom?”
Shannon Downey from Proven Winners ColorChoice Flowering Shrubs has spent much of her career answering that question. Sitting at a large, round table in Pasadena, Calif., she is answering that question again. This time, to a group of garden writers.
“It really depends on the type of hydrangea you have,” she says, probably for the thousandth time. After gardeners figure out what they have and how to treat it right, the garden will be filled with a plethora of amazing flowers for most of the summer.
The only way to discuss the different varieties of the shrub is to use their Latin names. Hydrangea will be abbreviated to the letter H, with the Latin species name following.
The most common variety in our gardens is the bigleaf or mophead hydrangea referred to as H. macrophylla.
“We do not recommend pruning them ever,” Downey says, “because no matter how careful you are, you're going to be sacrificing the blooms for next year.”
That variety forms the flower buds during the summer and fall. If they are removed by pruning, forget about flowers the next season. That pruning advice is also true to two other hydrangeas. H. serrata is the mountain hydrangea. It's similar to the mophead but is known to be a little tougher and very cold-tolerant but is, many times, not quite as showy; breeders have changed that though. New types of H. serrata can be stunning. The cold-hardiness of the mountain hydrangea is being bred into new introductions, too.
The oakleaf hydrangea — H. quercifolia — also blooms on what's called old wood and should not be pruned either. The plant produces big, white conical blooms with large leaves resembling oak leaves, hence the name. The flowers fade to pink and the foliage turns deep red in the fall, and it has tan, exfoliating bark for good winter interest.
For these varieties which shouldn't be pruned, Downey offers sage advice: “This is one of those instances where it's really important that you put the right plant in the right place.” Choose carefully when buying hydrangeas and read the plant tag: There are varieties that will reach 8 to 10 feet and others only a few.
Climbing hydrangeas —H. petiolaris — are great vines for growing in part shade. They are slow growers, reaching 30 to 40 feet at maturity, and they need support to climb. Patience is key with this plant as it can take several seasons to bloom. It flowers on old wood, but since it's a vine, it would rarely be pruned anyway. The white flowers are a magnet for pollinators.
Annabelle hydrangeas — H. arborescens — are one of the easiest to grow, blooming on the new wood that sprouts in the spring. They produce large white blossoms on stems that can reach 8 to 10 feet. The flowers are great for cutting and will bloom yearly without a fuss. The toughest of all are the native arborescens, which populate forests. They will grow just about anywhere and bloom reliably.
‘Invincibelle Spirit' was the first pink Annabelle variety; it was released in 2009. It's an indestructible, repeat bloomer that will set flowers even in full shade. The blooms aren't as big as those out in the sun, but they are still a beautiful pink and last for most of the summer. A new version called ‘Invincibelle Spirit II' offers improvement over its older cousin. “It has stronger stems, better shape, brighter color, ages to green instead of brown, but it still has the same great rebloom,” Downey says.
For each plant sold, the company donates $1 to the Breast Cancer Research Foundation. To date, they have raised over $835,000 for the foundation.
PeeGee, or panicle hydrangeas — H. paniculata — are another variety that doesn't ask for much from the gardener. It's large white flowers are produced on new wood, so pruning is not an issue with these varieties, either. It's vigorous, and some can reach as high as 15 feet tall. The plant is popular with breeders, and there are countless interesting types offered at local nurseries.
These varieties that bloom on new growth can be pruned in late winter to encourage better branching and stronger blooms.
Improper pruning is just one of the reasons hydrangeas don't bloom, mostly with the types that bloom on old wood. On varieties like mopheads, the buds can freeze in winter or be hit by a late frost. One way to protect them is to surround them with burlap supported by wooden stakes.
Hydrangea buds are a favorite food of deer. The shrubs should be protected with some type of physical barrier or sprayed with a repellent to keep the buds safe.
Another deterrent to blooming is lack of light. Even though the plant shows up on many shade gardening lists, Downey says sunlight until late afternoon is the perfect place to site a hydrangea. Most can take full sun, except in the South, where shade will prevent wilting in the late afternoon.
Fall is the great time to add hydrangeas to the landscape; after they are in place, they can last for decades or longer.
C.L. Fornari, a garden writer, speaker and radio host from Sandwich, Mass., has been growing the shrubs for years. She says they should be sited in morning sun with shade in the afternoon. It's not that the plant can't take full sun, she says.
“All hydrangea flowers last longer if protected from the midday sun,” she says. “They keep their color into the fall if they are not burnt out by the sun.”
She recommends improving clay soil with organic matter in as wide an area as possible. After the plant is in the ground, she advises to use compost as a mulch around the base of the plant.
She has one more planting tip: “I wouldn't plant it in a low spot where it's going to have its feet wet all winter,” she says.
Fornari participated in a trial for a new variety of Endless Summer hydrangea called ‘BloomStruck' this season. Like all Endless Summer varieties, it blooms on both new and old wood. She lights up when she talks about “the world of blue,” as she calls it.
“You have to talk about the world of blue in the garden, because there really aren't that many really true blue flowers,” she says with a big smile. “So, it's not that big of an area, but it's a very important area, because it's such fantastic color to have.”
She loves the intensity of the blue flowers ‘BloomStruck' throws, much more than the original Endless Summer varieties and ‘Nikko Blue,' another popular mophead type.
“The ‘BloomStruck' has a slightly smaller flower but seems sturdier,” she says.
Fornari has some ideas about what colors to pair with blue. She says you can't go wrong with yellow and white. “If you want to get snazzy, you put a little dash of paprika to spice things up,” she says.
The color of most hydrangeas is affected by the pH of the soil (sans white varieties). To change flowers from blue to pink, lower the acidity by adding lime; to change from pink to blue, raise the acidity by adding elemental sulfur.
Fornari evaluates lots of recently introduced plants. Although many might be skeptical when trying new varieties, she looks at it differently.
“I think one of the greatest things about gardening is that it encourages optimism,” she says. “You always assume that everything you plant in your garden is going to do well and be the best thing ever. And that is a very life-affirming approach to take. And then, you hope for the best, just like you do in life.”