Rose of sharon blog

Rose of Sharon Hedges

Introduction to Rose of Sharon Hedges:

Anyone that grows a Rose of Sharon for a few years will quickly learn how versatile these plants truly are. Not only are they stunning to look at with their profuse blooms all season long, but the Rose of Sharon is incredibly easy to shape into a variety of desired shapes! Most varieties will grow upwards of about 8 feet or so tall, with a spread of around 4 to 6 feet. This growth habit makes them natural candidates for creating blooming hedges!

There are a number of ways you could create Rose of Sharon hedges out of a group of these bushes. There are short varieties that only grow about 5 to 6 feet tall, and since that is also the normal height of a fence line, those are great varieties to create a border. Using the shorter varieties also makes trimming a breeze. After all, wouldn’t you rather trim a bush that only grows 6 feet tall rather than one that could get away from you up to 10 feet?

Creating Rose of Sharon Hedges:

The first thing you need to do obviously is choose the plants you would like to make the hedge row out of. Now one important point to consider is Rose of Sharon are deciduous bushes, which means they will lose their leaves in the fall. So if you are looking for a privacy hedge, these are probably not the best choice for your landscaping. On the other hand if you are only looking for a seasonal hedge border, for instance around a swimming pool where you would only be using it during the warm summer months, then these would make a great option. Be warned however, bees love these bushes!

With that out of the way it’s time to choose your plants. You can pretty much order whatever combination of colors you would like, but pay special attention to the size your choices get at full maturity. It would look strange if you were to pair up a smaller variety like the Lil Kim, with a tall variety like the Blue Satin. Try to choose varieties that in the end will grow about the same height. This is not only for consistency across your hedge line, but it also will make your Rose of Sharon hedges easier to manage if you can’t stay on top of them as much as you would like to.

Pruning Rose of Sharon Hedges:

Pruning your Rose of Sharon bushes is actually quite simple and should be done early in the plant’s life in order to achieve the best results. If you allow it to grow unchecked for too long, your plant will establish very thick trunks from which it will branch off. Once these trunks are established it is difficult to train the bush to do anything else without gutting it and severely hampering it. So before you get any of them into the ground, take a moment to decide what shape you are going to go for.

There are two traditional styles of shaping Rose of Sharon hedges. One way is to force the bush to grow out of a single main truck, as was mentioned above. This is relatively easy to do as you just choose the biggest and healthiest branch in the center of the bush and prune all others. Then don’t allow the bush to grow any offshoots on the bottom 2 feet or so of trunk, and this forces it to grow leaves and branches up high. Using this method you are effectively creating a Rose of Sharon tree. You can line multiple plants up like this side by side to create a row, but obviously with them being open along the bottom, it does not offer much in the way of privacy.

The other method is to take hedge trimmers and essentially shape them as a whole early one, before they are able to establish a few main trunks. In this fashion you are shaping them the same way you would any other hedge plant. You need to keep them tended often however because the longer you allow the new branches to get, the thicker and tougher the older, inner branches will form, making I harder and harder to maintain a compact shape. You can square off the bushes or use the trimmer to make them rounded, either way give them a quick prune at least twice a month to maintain the desired shape. After the 2nd or 3rd year of maintaining a disciplined shape, you will find that your Rose of Sharon hedges are much easier to keep as they will have established their growing habit around that shape.

Growing Conditions for Rose of Sharon Hedges:

The growing conditions for Rose of Sharon hedges believe it or not are actually quite forgiving. Just like their distant rose cousins, the Rose of Sharon requires a lot of direct sunlight to keep giving you all those beautiful blooms throughout the season. Unlike their high maintenance cousins however, the Rose of Sharon can tolerate much hotter and drier conditions. This is a feature that makes them favorites of gardeners everywhere.

It is actually quite easy to work a Rose of Sharon into most landscaping ideas, and it’s tough to argue the value all those colorful blooms bring to the garden. One thing to consider when creating hedges out of these bushes is they do not do as well in shady locations and they can become quite susceptible to fungal diseases if grown in too much shade. One of the reasons for this is shady areas tend to stay wet longer, and the Rose of Sharon prefers a drier soil. You can help prevent this by making sure the soil you grow them in has very good drainage.

If you give them the right growing conditions, and stay on top of their care for the first 2 or 3 seasons, you will find these bushes make exceptional hedge rows and you just can’t find any other hedge that will bring this much color and flair to your landscaping.

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A hedge of Rose of Sharon (Hibiscus syriacus) near us used to look absolutely show-stopping in late summer – a time when flowering trees and shrubs are rare, and rarely so generous with their flowers. Tired of being stopped by people asking what it was, the homeowners resorted to posting a sign: It’s called Althea!* Althea is another of this plant’s common names, as is rose mallow. Some, like today’s covergirl, look rosier than others.

My friend L-A has one that’s particularly rosy. Note the bee, one of many that day.

My friend L-A planted our covergirl in her garden 20 years ago. She isn’t sure of the cultivar, but my research suggests it might be ‘Lucy.’ For L-A, it blooms reliably like this for about a month, from early August to September. All she does is trim it a lightly every other spring, “if the branches are close to reaching the eaves of the house.” As she says, very scientific.

As you can see, it’s pretty well loaded with double blooms.

It’s a pretty tough customer, not minding baking sun and dryness. In fact, L-A moved it from one side of the bed to the other just a few years ago, and it came back strong.

I asked L-A if she has problems with it seeding itself around, because Rose of Sharon is a notorious self-seeder. My neighbour M has an increasing number of these trees in his tiny yard, and I’m always pulling out seedlings in mine. L-A hasn’t noticed this particularly.

However, in the U.S., Hibiscus syriacus is on invasive plants watch lists in a number of states. Here, for example, is a map showing early reports of its invasive tendencies. Mind you, it isn’t quite as dire as that state-by-state map appears. This version breaks it down by county, and as far as I can tell when viewed today, each county has only one report.

Ontario’s Invading Species Awareness Program doesn’t have it on their radar. Yet. But it’s good to keep any plant’s wandering tendencies in mind when selecting them for your garden. Unless you really like weeding.

Growing under Norway maples, it’s not nearly so showy

The example above seeded itself into M’s front yard, and clearly isn’t showing any show-stopping qualities. H. syriacus prefers full sun to part-shade. Deep shade doesn’t cut it.

When grown from seed, the flower is variable in colour, and can be white, pink or mauve. The only way to ensure you get the same flower as the parent plant is through cloning via soft-wood cuttings or layering. (To layer, you pin a young lower branch to the earth till it forms roots.)

M’s volunteer tree has a single form of the flower

You can see the similarity of the single flower to others in the mallow family (Malvaceae) such as the tropical hibiscus and hollyhocks.

Here you can see a developing seed capsule (left) and a flower bud (right)

One way to control Rose of Sharon’s wandering ways is to deadhead the seed capsules. On a specimen as floriferous as L-A’s this might be a chore, but so is pulling up a potential forest of seedlings. Each capsule produces many seeds, as you’ll see below, and most are viable.

The capsules dry on the branch, pop open and sprinkle their seeds over winter. The star-shaped dry capsule is an easy way to ID Rose of Sharon when the plant is not in leaf.

Considering I’ve yanked out so many, you’d think I’d have a photo of the seedling, but my flying fingers have been too eager to uproot the demons. The primary leaves are rounded and look slightly frilly. Quite different from the serrated secondaries. In fact, it took me a while to recognize what they were. Here’s a Wiki image for reference.

Immature seeds in the 5-section capsuleYear-old capsule, with a couple of seeds remaining

That said, the U.S. National Arboretum has bred a handful of cultivars that produce “little or no seeds” – they’re not, as some call them, completely sterile. They have names from mythology, such as ‘Diana’, ‘Aphrodite’, ‘Helene’ and ‘Minerva.’ The picture of ‘Diana’ at that link looks quite appetizing, but my hero, tree guru Michael Dirr, has this to say about it,

“Have grown ‘Diana’ and ‘Helene’ without becoming attached, do not show great vigor but flowers are excellent; ‘Diana’, particularly, is weak, humpy, rather wimpy form.”

Dirr’s reviews are never “humpy” or “wimpy.” Which is why he’s my hero.

This fence seedling from M’s tree snuck into my yard, despite my vigilance. They grow very quickly.

Although its white flowers are pretty, I’ll be uprooting the seedling that decided to take up residence in a more-neglected back area of my garden. This grew enough in one season to produce flowers – and seeds and, if untended, children and grandchildren. Beware.

If you’re still not discouraged from growing Hibiscus syriacus, here’s a PDF info sheet from Ohio State University which, in USDA Z5/6, is a similar climate to Toronto. Just keep an eye on the potential population explosion, and don’t plant it where it might escape into the wild.

(*As a footnote, a few years ago, a fence was constructed in front of the hedge we opened our post with, thwarting any horticulturally curious passersby.)

One day right after we moved to Mississippi, I got a call from a homeowner with a question about her althea plant. I was stumped, but soon found that the plant she was referring to was commonly called rose of Sharon.

This is an old-time landscape and garden deciduous plant. Many folks mistakenly call rose of Sharon a hollyhock, as the flowers do look fairly similar. They are big and bold in the landscape, and I’ve seen many planted in the wrong locations, blocking window, doors and porches.

I’ve recently become fascinated with some of the newer selections from Proven Winners: Orchid Satin, Purple Pillar and Pollypetite.

Orchid Satin has large, beautiful, single orchid-pink blooms with a dramatic red eye accent. My plant is small now, and I’m growing it in a 4-gallon container, but I’m amazed at its soft and graceful branching habit.

This plant has the potential to be medium-sized with a mature height greater than 10 feet and a 4- to 6-foot spread. I’ll have to bump it up into a larger container in a couple of years. This plant tolerates pruning in the late winter or early spring. Feed every spring with a controlled-release fertilizer.

I really like the fact that Orchid Satin is a sterile, seedless selection, which means I don’t have to weed out seedlings every year.

Most rose of Sharon shrubs have the potential to be large — especially wide — landscape plants. If you have a narrow space, then Purple Pillar is the rose of Sharon for you.

This selection naturally has a columnar growing habit. It will grow to 10 feet tall or more but only 3 feet wide. This narrow growth habit creates very few branches, which means pruning is rarely required except for some tidying up in early spring.

One thing I like about the plant is that each stem becomes covered along its entire length with bright-purple blooms, each with a dark purple-red eye. Each flower is a semi-double, having two or more layers of petals with the pistil and stamens visible.

If you still don’t think you have enough room for Orchid Rose or Purple Pillar, I’ve got one more rose of Sharon for you to consider. There are three reasons you ought to grow Pollypetite in a small landscape space.

Pollypetite has a dwarf habit that is fantastic, only reaching about 3 to 4 feet tall and wide. This plant has large, lavender-pink flowers that contrast nicely with its dark-green foliage. And my third reason is that Pollypetite is nearly seedless, so weeding is not necessary.

As with Orchid Satin and Purple Pillar, Pollypetite needs no special care. Pollypetite is a new selection for 2018, so be patient for your favorite garden center to get in stock.

All three of these selections have been appealing additions to my eclectic collection of colorful containers and plants in my home landscape. I highly suggest you try them in your garden and landscape this year.

Here’s to Rose of Sharon

To Prune or Not to Prune?

Beyond a fresh layer of mulch in spring, routine care includes pruning (if desired) in late winter or very early spring. Some gardeners cut their shrubs back very hard – to 3 or 4 buds per shoot — to control overall size and encourage larger blooms. Others simply take the laissez faire route and let their shrubs grow into their natural shape. This latter approach encourages more, smaller blossoms. The plant blooms on the new wood of the current season — summer trimming means that you’ll lose out on flowers.

She’s a hardy plant with gorgeous blossoms that needs little care — what’s not to love?

Barbara Martin is National Gardening Association’s reporter for the Mid-Atlantic region. Maggie Oster also contributed to this article.

Photography by Barbara Martin/National Gardening Association

Luscious Bloom

Breeders have developed some lovely flower colors — white, pink, red, violet, and lavender-blue — available in single or double forms. Rose of Sharon sports her blossoms, which resemble those of other members of the mallow family, from mid- to late summer. I especially like the blue ones, such as ‘Blue Satin’ (although to my eye they are still more blue-violet than true blue, except in soft early morning light). Many of the double-flowered types seem almost more like oversized rose trees, with eye-stopping, multi-layered crepe paper flowers. The white-flowered cultivars are perfect for an all white summer “moon garden,” and the many pinks and purples work well among the pastels of English-style gardens.

Also, the U. S. National Arboretum has introduced new cultivars in recent years that are triploids. The flowers are large, but they don’t set seeds, so blooms are produced over a long period. ‘Diana’ is among the best of these introductions, with pure white flowers that remain open at night. The foliage is a waxy and dark green. ‘Aphrodite’ has rose-pink petals that are red at the base. ‘Helene’ has white flowers with deep red centers with streaks forming many-pointed stars. ‘Minerva’ has lavender-pink flowers with a red center.

I first noticed the hardy shrub called Rose of Sharon (Hibiscus syriacus) while traveling one midsummer across the southern plains. I saw it over and over again, blooming bravely in dooryard gardens despite the sizzling heat on the rough, wind-swept prairies. That’s when I discovered that this large, summer-flowering shrub reliably brings pleasure and beauty, whatever the weather dishes out. That, to me, is the sign of a quality plant.

This native of Asia and India was introduced to the U.S. in 1790. Hardy in USDA Zones 5 through 8, Rose of Sharon thrives in full sun and isn’t too fussy about soil, as long as it’s not sodden or very dry. The vase-shaped shrub grows 8 to 12 feet tall and to 6 to 10 feet across, but can be pruned to a smaller stature. Many books suggest using Rose of Sharon in a shrub border rather than as a specimen plant in the yard, but I’ve noticed that those grown alone develop a much better shape than those crammed in a shrub border.

If you plant Rose of Sharon in fall, don’t be dismayed in springtime if it looks dead while surrounding plants are busily sprouting away. The three-lobed leaves emerge quite late. I, for one, am willing to accept this quirk because of the shrub’s contribution to the summer garden. There is nothing to equal its stately presence amidst the daylilies, coneflowers, reblooming clematis, and sweet peas, with butterflies and hummingbirds all around it. Not bad for a low-maintenance, workhorse of a shrub!

While some gardeners find its persistent, woody seed pods an asset in the winter landscape, many gardeners shun Rose of Sharon – at least the old fashioned type – for the prolific, weedy offspring. This group will be won over by recent introductions, including triploid and tetraploid varieties, that set little if any seed.

As for pest problems, there are few. Japanese beetles love Rose of Sharon, so be prepared with your favorite means of beetle avoidance, be it traps, repellents, or grub control.

Vermont Garden Journal: The Rose Of Sharon Shrub Is In Bloom Now

Listen Listening… / 2:30

The naming of plants can be deceiving. Take the Rose of Sharon shrub that’s blooming now around the state. This plant isn’t in the rose family. Even the botanical name, Hibiscus Syriacus is only half correct. It has a hibiscus or mallow-shaped flower, but the shrub doesn’t hail from Syria, more likely India or China.

However you look at it, the Rose of Sharon is a beautiful landscape plant that has become very common. What’s not common about Rose of Sharon is its ability to flower profusely in August when few other shrubs are blooming and be relatively trouble free. The flowers can be single, double, frilly or of multiple colors. Yes, there is a Rose of Sharon called ‘Tri-Color’ that has pink, red and purple colored flowers all on one shrub. ‘Sugar Tip’ has double pink flowers on a variegated plant. ‘Lil’ Kim’ only grows three-to-four feet tall, while most Rose of Sharon shrubs reach up to 10 feet. And the ‘Pillar’ Rose of Sharon only grows two feet wide, but straight up.

Give Rose of Sharon full sun and well-drained soil on a zone five site and it’s happy. In marginally hardy areas, protect shrubs from winter winds with burlap. Be patient in spring as Rose of Sharon can leaf out late. The only serious pest of Rose of Sharon is the Japanese beetle.

While most gardeners grow Rose of Sharon as a specimen in the lawn or a foundation plant along the house, play around with this versatile shrub. Grow Rose of Sharon with other shrubs such as nine bark, lilac and smoke bush. Grow a privacy hedge of Rose of Sharon to block a view. Or even grow dwarf types in containers, then protect them in winter.

Now for this week’s tip: keep picking off and destroying the tomato hornworm. These caterpillars eat voraciously and grow fast, stripping tomato foliage in a few days. Toss the caterpillars in soapy water or feed them to chickens.

A shrub to brighten the dog days of summer

In the world of garden shrubs, the rose of Sharon has a lot going against it. The leaves are drab with no fall color; the bush is twiggy, stiff and ungainly; and the light-gray bark is simply dull. But the rose of Sharon has one redeeming quality: In mid- to late summer, it has something few other garden shrubs can produce: blossoms.

We speak not of the demure, pearly blooms of the mock orange or spirea, but brassy saucers surrounding a central spike of pollen. Think of it as a satellite TV dish for the fairies.

Unnamed single red varieties of rose of Sharon by the British plant breeder Roderick Woods. (Roderick Woods)

It is this flower ornament in the dog days of summer that elevates the plant. Among trees and shrubs, there isn’t much else in flower in August — a month when certain perennials and, especially, ornamental grasses come to the fore. If you discount roses, the gardener is scrounging for action from trees and shrubs and turns to crape myrtles, the Japanese pagoda tree or the PeeGee hydrangea.

Overshadowed by an ever-expanding palette of crape myrtles, the tired old rose of Sharon seemed to have vanished from view, or at least the gardener’s consciousness, but, lo, its star is ascendant once more.

For reasons more to do with serendipity than a grand plan, the rose of Sharon is in the midst of its most comprehensive makeover in years, maybe ever. The resulting varieties are coming closer to creating a shrub that can be integrated into the garden as worthy ornamentals and not just because they plug a flowering hole.

Breeders in Europe and South Korea are developing versions with better flower colors and forms, and plant shapes that are smaller and generally less awkward.

“They aren’t always the most easy plants to use in the landscape; to have a more rounded, denser habit is something we look for,” said Stacey Hirvela, of Spring Meadow Nursery in Grand Haven, Mich. The wholesale company develops and distributes shrub varieties under the Proven Winners brand.

Rose of Sharon blooms are redolent of the tropical hibiscus plants found growing in patio and balcony pots, and to the plate-size blooms of the native rose mallow. All belong to the genus Hibiscus. Botanically, the rose of Sharon is Hibiscus syriacus.

Another one of its faults is its prodigious seeding: You will find old specimens — they are hardy and live as long as lilacs — with dozens of seedlings growing at their feet. The fastidious gardener would remove the blooms as they faded to prevent seed set. This chore, if it was ever popular in Washington in the heat of August, is no longer a favorite pastime.

Several years ago, a series of new varieties from the U.S. National Arboretum revived the shrub’s fortunes. The first, named Diana and producing white flowers, was released in 1970 and was followed in the 1980s by Aphrodite (pink with red eye spot), Helene (white with red eye spot) and Minerva (lavender with red eye spot). The flowers were large and durable, and because they were sterile, or nearly so, the shrubs just kept blooming for weeks. (Plants typically stop growing new flowers when fertilized.) This sterility also solved the problem of the self-sowing of seeds. Aphrodite, the largest of the group at nine feet high, has become the most widely used, in my experience.

Blue varieties are harder to breed because of the color’s recessive genes. This is one of retired Cambridge University professor Roderick Woods’s anemone-flowered varieties, Blue Chiffon. (Proven Winners)

Blue is a choice color in this plant, and the standard variety for this was Blue Bird. I always thought this a valuable plant in the back of a border, where its ugly ankles and twiggy habit could be disguised until it took the stage in midsummer. But I haven’t grown it, and I read that it has problems beyond seeding: It’s open in habit and has a short season of bloom. It has been superseded by Blue Satin, a stronger color and a better grower. I recently saw a 10-year-old specimen that had reached 15 feet.

Blue Satin sets seed, however, and has been upstaged by a seedless version named Azurri Blue Satin. It is one of several Satin varieties developed in the United States by Spring Meadow as a line of large, single and sterile or near-sterile shrubs. The group also features Blush Satin, white blush; Rose Satin, pink; Ruffled Satin, pink with a burgundy eye; Orchid Pink; lavender-pink with a prominent red eye; and Violet Satin, violet with a red eye.

Woods evaluates a seedling in his greenhouse in Norfolk, England. (Proven Winners)
Woods’s Pink Chiffon resulted inadvertently from an effort to find a clearer, stronger pink variety. (Proven Winners)

One of today’s most interesting breeding programs can be found on a six-acre farm in the east of England where a retired Cambridge University professor named Roderick Woods has been working his magic. In his academic incarnation, Woods was an expert on human physiology and developed protective clothing for hazardous occupations, but his fascination with the rose of Sharon has abided since his childhood in the 1950s, when his parents grew them.

As a breeder, he has been working on improving the size and color of the flowers — they are traditionally muddy and age to a gray — and he has raised 18,000 seedlings to flowering age since 1980. The vast majority are discarded in the quest for a better rose of Sharon. While trying to develop a stronger single pink from seed sent from Japan, he found seedlings that were slightly double — they’re known as anemone-flowered — and from this came the Chiffon line, now gaining traction in U.S. gardens. The series features Pink Chiffon, White Chiffon, Lavender Chiffon and Blue Chiffon. The last was the hardest to develop because of the recessive nature of blue-flowered genes, but the wait looks worth it, with large blue flowers at eye level in late summer.

Blue Chiffon flower detail. (Proven Winners)
Azurri Blue Satin is a low-seed improvement over Blue Satin. (Proven Winners)

Woods seems even more excited about a line of new single-flowered types in pink, white, deep purple, dark red-purple and light red. “The flowers are 50 percent bigger than others and open perfectly flat with overlapping petals, so the flower power is better than anything else on the market,” he said. They are being trialed in Europe, but their appearance here may be harder to achieve because of new restrictions on hibiscus importation to safeguard citrus growers against a pest risk.

White-flowered Lil’ Kim, bred for the smaller garden. Red and violet versions are available. (Proven Winners)

One other drawback to rose of Sharon is the sheer size of the shrub. This is not a plant for a small urban garden. However, in Korea, a breeder named Kyung-Ku Shim has developed dwarf varieties named Lil’ Kim. Three are available in the United States, in red, violet and white. Beyond their size — at three to four feet, they are less than half the size of a regular shrub — the dwarf varieties have a more pleasing leaf texture and overall habit.

“These varieties have very small leaves and really dense bud set, so instead of looking at a mass of foliage all season, they have a more elegant habit,” Hirvela said. They are also sold under Proven Winners’ ColorChoice brand and have wide distribution in independent garden centers known for their range of woody plants.

Another innovation is a variety named Purple Pillar, developed in the Netherlands. It has semi-double flowers, pink-purple with extended red eyes, and although it grows as tall as a regular rose of Sharon, it gets just three feet wide. Because I have a young plant, I haven’t seen it in its glory, but I think this would be a good vertical accent in a border of seasonal highlights.

Another developer and grower of new varieties, Bailey Nurseries in Newport, Minn., has introduced four semi-double flowered varieties — Tahiti, Fiji, Hawaii and Bali — with a size and intensity that suggest tropical blooms. This year it introduced the first in a series of French-bred plants that are fully double in bloom, as frilly as a carnation. The first is French Cabaret Blush, which is soft pink and white.

Purple Pillar forms a tall accent in a tight space. Most rose of Sharon varieties get six to eight feet wide. (Proven Winners)

The rose of Sharon likes heat and sun, another reason it’s so valuable in summer, and will take dry conditions once established but will benefit from some moisture. It’s also deer-resistant. Woods recommends cutting the shrubs back hard every six years or so, to reinvigorate the flowering.

Debbie Lonnee, of Bailey, sums up the appeal of this shrub and why it’s time to embrace it again: “It’s a super summer-blooming plant with a lot of appeal,” she said. And it stays that way until September, bridging that awkward dead time in the garden known in horticultural terminology as August.

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