A Gardening Journal

The Best Season Ever: Pink-flowered Wild Hydrangea

Hydrangea arborescens Invincibelle Spirit fronting Picea glauca Sanders Blue 010816 640

 

Hydrangeas might be unique in that their flowers dry in place right on the stem, to create a second season of interest that can last through Fall and much of Winter. The flowers of other plants can mature into a second show of pods, seed heads, or fruits—and bravo for them. With hydrangeas, it's the flowers themselves that make Act II great.

 

Below, a close-up of a flower head of this form of wild hydrangea, Hydrangea arborescens 'Invincibelle Spirit'. As is typical of hydrangeas, all the flowers with what seem like comparatively large petals are sterile. The fertile flowers are barely visible even when fresh, and by now have matured to the tiny seed-bearing structures called capsules. You may just be able to make out some of these: They look like clusters of grains of sand amid and below the showy infertile flowers.

 

Hydrangea arborescens Invincibelle Spirit flowerhead closer 010816 640

 

Although you wouldn't grow wild hydrangea for its colorful Winter stems alone, their shades of warm brown are showy enough that you could groom the colony in Fall to enhance the display. See option five in the second "How to handle it" box, below.

 

Hydrangea arborescens Invincibelle Spirit stems 010816 640

 

The fluffy flower heads of this ever-popular species of hydrangea can look as good all Winter in a vase as in the garden. When they debuted in Summer, this form's flowers weren't the usual white. 'Invincibelle Spirit' blooms in shades of pink, making wild hydrangea a must-have all over again.

 

Here's how to grow this unusually flexible and accommodating shrub:

 

Latin Name

Hydrangea arborescens 'Invincibelle Spirit'

Common Name

Pink-flowered wild hydrangea, pink-flowered smooth hydrangea.

Family

Hydrangeaceae, the hydrangea family.

What kind of plant is it?

Very hardy deciduous shrub.

Hardiness

Zones 3 to 9.

Habit

Clumping and, in time, colony-forming, with many comparatively slender stems arising from the roots without ever forming a woody central base. Individual stems live for only a few years and, so, develop neither thickness or height. And even before they die overall, they often develop partial dieback. Grooming this shrub might seem to be a nightmare, but is anything but. See "How to handle it" as well as "Quirks," below.

Rate of Growth

Fast.

Size in ten years

A clump three to four feet tall and wide.

Texture

Usually full but not heavy: Because normal handling means cutting the stems to the ground annually, it's rare for any of them to mature sufficiently to develop side branches. Stems arch outward naturally as they grow, perhaps assisted by the ranks of projecting foliage as well as the size and weight of the flower heads. Because they are very close together when they emerge, this arching ensures a pleasant spacing.

 

The pruning tactics in the second "How to handle it" box, below, create growth that is lower and with side branches—and therefore also denser. Even so, 'Invincibelle Spirit' will never be as dense or rigid as, say, 'Autumn Joy' sedum, where nearly all stems project straight upward and the large flower heads atop them form a motionless pavé surface. 

Grown for

its flowers' pink color: This native shrub and its white flowers have graced gardens for many generations. To have flowers in a different color—and with such depth of hue, too—is big news, indeed.

 

its flowers' ability to dry in place, and to then be harvested for dried arrangements: This trait is shared by many hydrangeas, but the proportion of large-petalled sterile flowers to small-petalled fertile ones can change the look of the dried heads dramatically. See how different the fresh as well as dried heads of 'Pink Diamond' hydrangea are: With comparatively few sterile flowers, they are much more open; they are also conical instead of hemispherical.

 

its ease of establishment as well as maintenance: As is typical for nearly all forms of Hydrangea arborescens (see "Variants," below for an exception), 'Invincibelle Spirit' establishes quickly and—provided it receives sufficient moisture—lives forever and blooms faithfully. Although there are some fussy pruning options, the normal yearly handling is by far the polar opposite of the meditative, skilled judgement calls presented by each stem of other hydrangea forms such as climbing, mophead, lacecap, and oakleaf, where it's best to wait for the right season or even week to prune each stem back individually. With wild hydrangea, it's just fine to mow the whole colony down willy-nilly any time from hard frost until the next Spring. If your siting and equipment are right, feel free to to mow literally. See "Quirks," below.  

 

its unfussiness about soil: As long as it is growing in soil that doesn't ever dry out, 'Invincibelle Spirit' will grow even in clay soils as well as normal soils that can become temporarily saturated because they are near ponds or streams, or are in low spots that collect rain run-off. That said, this is not a shrub for marshes or areas that remain flooded for days and weeks during the Winter. Regular garden soil is fine, too. See "Where to use it," below.

Flowering season

In warmer climates with long growing seasons, June into July and again in August into September. In colder climates (which usually have shorter growing seasons, too), just late June into July.

 

The potential for two flushes of bloom in warmer climates is counterbalanced by the somewhat shorter duration of each. In colder climates, the June flowerheads could remain colorful for two months; by then, the end of the growing season is just a month or so away, and they can be allowed to persist into Fall and Winter. In hot climates the heads are likely to fade to their Winter—i.e., dead and tan—colors in July. That's far too soon for any shrub with such prominent heads of bloom to be communicating that "Yes, I'm all done for the season. This is it right through until April." A mid-summer deadheading will usually seem a priority. Although it may well encourage that second flowering, it's also a second round of maintenance for a shrub that, up North, needs just one.

Color combinations

The flower buds are a deep and vivid pink, and the flowers themselves only a bit lighter, so keep 'Invincibelle Spirit' far away from orange, red, and deep yellow. Instead, associate this cultivar with white, pink, rose, blue, purple, burgundy, and ebony.

Plant partner

In thinking of a setting for 'Invincible Spirit' that is stylish and practical, ponder whether the Winter display of dried-in-place flower heads and stems is important enough in your particular garden to warrant special consideration, or whether you need consider just the leafy and pink peak of the Summer display. If the latter, the stems aren't visible, and surrounding plants need "only" harmonize with that season's flowers.

 

In addition to being pink-friendly, immediate companions will also need to be moisture tolerant, as well as comfortable with the same amount of sun or shade. What about clematis? Most are moisture-lovers, with flowers in just the shades of pink, white, and blue that look best with the pink shades of 'Invincibelle Spirit'. And depending on the forms you choose and how you prune them, they can be in flower whenever the hydrangea is. All of their flowers are much larger than those of the hydrangea, too, so the harmony in coloring is enhanced by the contrast in scale. A 'Huldine' clematis that I planted so that it could climb through a 'Ghost' weigela has also wandered in the other direction into the 'Invincible Spirit'. Its white flowers are backed with rosy-pink bars. There are dozens of other forms of clematis to consider, too.

 

My full-sun setting also enables me to grow Hibiscus moscheutos nearby. Its enormous pink flowers are just the match in color, and couldn't be more of a contrast in size.

 

If your 'Invincibelle Spirit' receives shade, clematis can still succeed, but you could plant astilbe or summer-flowering forms of azalea instead of the hibiscus.

 

These warm-weather companions may take up most of the available sun, moisture, and nutrients—let alone space—near your 'Invincibelle Spirit'. If there's still room, consider a companion that enhances the Winter display of cinnamon stems and parchment-to-tan flowerheads. What about Bergenia at the very front of everything? Its leathery leaves turn burgundy in cold weather, and remain evergreen most of the Winter even in severe weather. It thrives in moist ground, too.  Vinca could also succeed, especially because it is so shade-tolerant it can thrive at the foot of other companions that peak when the hydrangea flowers are fresh in mid-Summer.

Where to use it in your garden

This cultivar is spectacular in flower and its annual cycle of maintenance is usually quick and easy, so it's a natural component of ornamental plantings as a single-clump specimen or specimens, even those that are closely-planted and detailed. It also succeeds en masse as a groundcover anywhere it receives enough moisture. Its shade tolerance also suggests use on the east or north side of hedges, fences, and buildings, where it would receive only morning or partial sun. Its preference for moisture and tolerance of ground that is occasionally saturated make 'Invincibelle Spirit' a natural for the sloping sides of a rain garden, although not its very bottom, where water could pool for days or even weeks at a time.

Culture

Full sun only in climates that are either cold and with short growing seasons or have cool and foggy Summers—or whose soils and setting ensure season-long access to sufficient moisture. In my garden, with rich but heavy soil and what  always seems like a high water table, I have planted 'Invincibelle Spirit' in full sun at the low front edge of huge beds. Run-off collects there, and the puddles last for a day or even two after heavy rains. I never need to water my established plants, these hydrangeas included, and yet their foliage remains in top condition the entire season.

 

Unless your conditions are similarly advantageous, provide part shade all day or full shade from late morning on. Ensure sufficient water by some combination of regular rainfall or irrigation, or through lateral penetration from adjacent always-saturated soil. 'Invincibelle Spirit' behaves like the straight species in handling moisture-retentive soils of almost any degree of looseness or compactedness, from those that are rich enough and friable enough for your fussiest rhododendrons to those whose moisture retention is due to a high proportion of clay.

How to handle it: The Basics

Plant at any time Spring through Fall that the soil is workable; in the first growing season, ensure enough water for establishment. By Fall, the flower heads will have dried in place. If you appreciate their look in the garden, let them remain into Winter as long as you'd like. If you usually complete garden clean-up in the Fall—or you'd like to harvest the stems for a dried bouquet—feel free to cut all stems to the ground at any time. Just be done before new growth begins emerging in the Spring; if you delay, you'll need to be careful not to damage the tips of young stems. This would slow the cutting-back greatly.

 

'Invincibelle Spirit' performs beautifully without some of the usual in-season assists, such as pinching the tips of new growth or staking young stems. If you're experimenting with a more-controlled look, you could place a peony hoop over your colony in early Spring so that stems are held more upright. In my experience, though, the natural arching of stems doesn't veer into floppiness.

 

Provided they receive sufficient water, clumps retain their vigor indefinitely simply by being cut to the ground once (or, in hot climates, twice) annually. Dividing and resetting is not necessary. If you would like to increase the area of coverage, or want to give 'Invincibelle Spirit' to friends, it is easy to chop through the perimeter of the colony to release a section. It's also easy to lift the entire colony and pull or cut it apart into small sections. As with de novo planting, this can be done any time Fall through Spring that the colony is dormant and the ground is workable.

How to handle it: Another option—or five!

In contrast to 'Annabelle' (see "Variants," below) stems of 'Invincibelle Spirit' are strong enough to be self-supporting. But you might want to experiment with growing your colony so that it flowers a bit earlier or later in Summer, is more dense, is even more upright, or is somewhat shorter. Try these tactics:

 

1. Cut the colony to the ground, as usual, any time from Fall to early Spring. When new stems are tall enough to have formed three or four ranks of leaves, pinch off the tips so that side stems will emerge. They will produce flowerheads at their tips, which will be smaller as well as later to form. This could be just the ticket if, say, you were using 'Invincibelle Spirit' as part of a scheme that you didn't want to peak until August, as might be the case at a Summer cottage where August is the most important month.

 

2. Do the annual cool-season cutback as you might for 'Annabelle' (see "Variants," below): by cutting only every other stem to the ground. The older stems that you've left in place will still produce flowerheads, but they will be smaller. More importantly, these older stems are a bit woodier than the newer ones. Coupled with their smaller flower heads, they will provide surprising support to the new and "big-headed" stems formed as a result of the cutting back. The next year, cut the older stems to the ground, leaving the year-old stems to become the supporters for new season's growth.

 

3. You might want to experiment with bringing 'Invincibelle Spirit' into bloom earlier in the season. (Perhaps you want the shrub to be in bloom by late Spring, before you leave for that Summer cottage.) Cutting the stems all the way down to the ground inevitably delays flower formation: A certain amount of new stem must be formed before buds can originate, and that takes a few weeks. For earlier flowering, cut stems back just to a foot or so high. These flower heads will not be as large as those atop stems produced as a result of to-the-ground cutbacks. But they will be noticeably earlier and, because they are smaller, even less susceptible to being weighed down in heavy rain.

 

4. For the longest possible season of bloom from a given colony of 'Invincibelle Spirit', combine all of these strategies. In late Winter or early Spring, cut some stems back to a foot and others all the way to the ground; leave still others untouched. After new stems emerging from the roots are six or eight inches high, cut back some by half while leaving the rest to develop on their own. You might have flowerheads emerging from May to August!

 

5. The stems mature in place too, not just the flower heads at their tips. As in the last picture, above, the thickest of them retain a warm cinnamon color whose display is worth enhancing. After the leaves have been shed in the Fall, go over the colony and cut any broken stems off at the ground. Also clip off at the ground any stems with a putty or white color; these not only appear dead in comparison to the cinnamon stems, they are. What will remain are all the cinnamon stems and the large flowerheads that top them. Note that these cinnamon stems are most likely to be those that emerged right from the ground, not older stems that you might have allowed to remain from prior seasons as in options 2, 3, and 4 above. Ah, the choices to be made with Hydrangea arborescens. The good news is that you can experiment year by year, to see which kind (or kinds!) of displays of flowers are the most satisfying in partnership with the best display of Winter stems.

Quirks and special cases

The large colonies formed by mass plantings could present hundreds of stems to be cut down each Winter or early Spring. Because stems are just as likely to emerge directly from the ground rather than emerging as side branches from the base of extant branches—and the flower heads on those ground-emerging stems are likely to be larger than those atop side stems—there is no need to leave behind stubs. But, all in all, this means a lot of "scorched earth" pruning.

 

If your colony directly borders lawn or paving, you can do the pruning mechanically with your lawn mower or brush hog. If you are gardening in a climate where the growing season is long as well as hot and your colony is growing in ideal conditions of rich, deep soil that enjoys unfailing generous moisture all season long, you could try giving the colony a second massacre in mid-season—say in late June—to encourage a second crop of stems and, August into September, flowers.

Downsides

Hydrangea arborescens does not tolerate drought and, so, is usually not advisable for locations in full sun unless the soil is water-retentive—and is restocked with moisture as regularly as needed. See "Culture" and "Where to use it," above.

Variants

Hydrangea arborescens just gets more interesting, so only gardeners with a willfully antique bent should consider planting the straight species. At the least, grow 'Grandiflora'. It was discovered in Ohio about 1900, and its flower heads are noticeably larger.

 

Flower heads of 'Annabelle' are larger still—eight to twelve inches across—and are staggering to see but challenging to keep erect: In wet weather, the heads can be weighted to the ground and tend not to right themselves when dry. Staking or corralling is rarely graceful, although, you could grow them through peony hoops if you had extras. Better, cut only every other stem to the ground in Spring. Stems from the previous year will produce much smaller flower heads and, not only will they remain more erect themselves, they will provide surprising support to the large flower heads produced by shoots from stems that were cut back hard.

 

Flower heads of 'Incrediball' are even larger than those of 'Annabelle'—up to a foot across—but, because its stems are also much thicker, the huge heads are reported as remaining upright even after soaking rains. 'Incrediball' sounds like the 'Annabelle' for this modern age of extreme weather.

 

'White Dome' resulted from a random cross-pollination in 1997; its flower heads forgo much of the impressive size of 'Annabelle' in favor of an even greater victory: complete self-supportedness.

 

Leaves of 'Green Dragon' are strikingly serrated and twisted, giving this cultivar plenty of interest even before the species' typical white flower heads emerge.

 

Flowers of 'Hayes Starburst' are double—which only increases the likelihood that the clusters will become so heavy in wet weather that they'll flop. But the flowers are striking enough that you might want to grow this shrub just for cutting, or at the top of a high retaining wall, so you can look up at the dangling flower heads.

 

Further pink-specific developments include 'Invincibelle Ruby', with burgundy flower buds and darker pink flowers, and 'Incrediball Blush', whose flowers are pale pink. Flowers of 'Invincibelle Spirit II' are a bit darker than the original 'Invincibelle Spirit', as are the leaves; the stems are stiffer, too.

 

Flowers of 'Lime Rickey' are green. 

 

H. arborescens ssp. radiata 'Samantha' was discovered in South Carolina—but grows better in colder climates up North. H. arborescens itself thrives even in the heat of subtropical Zone 9, such as northern Florida but, according to the nursery that introduced it, 'Samantha' doesn't thrive in climates warmer than Zone 6, which is roughly from Ohio through Connecticut. In addition, the cold hardiness of 'Samantha' is sometimes given as Zone 4, not the 3 of the species. Plus, in contrast to the species, whose native habitat is usually described as moist or even streamside soil, good drainage is advised for 'Samantha'. The white flowers of 'Samantha' are typical of the species, so why go to all the trouble of growing it? The backs of the leaves are a startling silvery white. Plant 'Samantha' in soil even moister than you would for the species—but also with better drainage and afternoon shade—so that you can choose an even breezier location that will flash the undersides of the foliage dramatically without also subjecting the shrub to foliage-damaging drought stress. More than once I have failed to establish 'Samantha', but this year will attempt to satisfy its finicky demands for both moisture and drainage: The foliage is that exciting!

Availability

Online and at retailers.

Propagation

By division; this very hardy shrub can be divided any time from Fall to Spring that the soil is workable.  

Native habitat

Hydrangea arborescens is broadly native to North America east of the Rockies: from Kansas and Oklahoma east, north, and south to everywhere from Florida to New York. 'Invincibelle Spirit' was developed by Dr. Tom Ranney, horiculturalist at North Carolina State; it debuted in 2010.

 
 
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