Shrub · Malvaceae
Rose of Sharon
Hibiscus syriacus
Give it full sun and room to breathe, and this tough shrub throws color from midsummer to fall.
Full sun
Every 7–14 days
USDA 5–9
8–12 ft · 2.4–3.7 m
Overview
Rose of Sharon is the shrub that carries the garden through late summer, when most flowering plants have called it quits. It belongs to the mallow family and stands as a hardy, upright deciduous shrub, opening fresh hibiscus-shaped blooms day after day from June into October. The flowers come in white, pink, lavender, and a violet-blue you rarely see elsewhere, many of them set off by a contrasting eye at the throat.
It earns its keep by being almost impossible to discourage. Once its roots are down it shrugs off heat, humidity, drought, and poor soil, and it rides out winters as cold as -20°F (-29°C). Growth is fast, and a plant can climb to 8 to 12 feet (2.4 to 3.7 m), which makes it a quick screen or a back-of-the-border anchor.
The one thing to keep in mind is that it self-seeds with real enthusiasm, enough to be flagged as invasive in a few states. If volunteer seedlings would be a nuisance where you garden, reach for a sterile cultivar like Diana and you get the long bloom without the spread.
Care
The short version: plant it in full sun and well-drained soil, water it through its first couple of seasons until it settles in, then prune it back hard in late winter and let it carry the late-summer garden on its own.
Light
Give it full sun for the heaviest flowering, though it will take partial sun or light afternoon shade. The more sun it gets, the more blooms you see, so a bright, open spot pays off all summer.
Water
Water young plants regularly while the roots establish, soaking deeply rather than sprinkling often. Once it's settled in, usually after a season or two, it turns drought tolerant and gets by on medium moisture and natural rainfall in all but the driest spells.
Soil
It isn't fussy about soil and grows in average, well-drained ground of almost any pH. It even tolerates poor sites, but it wants drainage, since soggy roots are one of the few things that trouble it.
Temperature
This is a tough customer that handles a huge temperature range, from about -20°F to 100°F (-29°C to 38°C). It takes summer heat and humidity in stride and survives hard winters without protection.
Humidity
Average outdoor humidity suits it fine, so there's no level to manage. What matters more is air movement, since crowded, still air invites the leaf spots and rusts it can otherwise pick up.
Feeding
It needs little feeding in decent soil. A single dose of balanced general-purpose fertilizer in spring is plenty, and going heavier on nitrogen only pushes soft growth that aphids love.
Pruning
It flowers on new wood, so prune in late winter or early spring before growth starts. Cutting the stems back hard, to 2 or 3 buds, trades a slightly smaller number of blooms for noticeably bigger ones, and shapes the shrub at the same time.
Repotting
Container plants rarely need repotting. Move one up only when you spot roots circling or pushing out the drainage holes, water running straight through, or growth stalling in the pot.
Size & spacing
Expect a fast-growing shrub of 8 to 12 feet (2.4 to 3.7 m) tall with a spread of 6 to 10 feet (1.8 to 3 m). Give it that much room so air moves through the canopy and the foliage stays dry.
When to plant
Rose of Sharon is grown for its late-season show, leafing out late in spring and holding its flowers from June well into October. Set new plants out in spring once frost has passed, or in early fall, and do the year's pruning in late winter before the buds break.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: late winter to early spring (8-10 weeks before last frost)
- Plant: spring after last frost, or early fall
- Harvest: June to October (mid to late summer)
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
This shrub is famously trouble-free, and most of what bothers it is cosmetic. The pests and spots below tend to show up on the leaves and buds first, so a quick look over the plant in summer catches them while they're still easy to handle.
Leaves chewed to lace through the summer
This is Japanese beetle damage, and the beetles work in clusters on warm days, leaving the foliage skeletonized between the veins. Pick them off by hand in the early morning and drop them into soapy water. Skip the pheromone traps, since they pull in more beetles than they catch.
Fix:
- Hand-pick beetles in early morning and drop into soapy water
- Avoid pheromone traps that attract more beetles
- Treat heavy infestations with an appropriately labeled insecticide following directions
Curled new shoots that feel sticky to the touch
Aphids and sometimes whiteflies cluster on the tender new growth and leave behind a sticky honeydew that can turn black with sooty mold. Blast them off with a strong jet of water, then treat what's left with insecticidal soap. Lady beetles and other natural predators usually finish the job if you let them.
Fix:
- Dislodge aphids with a strong spray of water
- Apply insecticidal soap or horticultural oil to affected growth
- Encourage natural predators such as lady beetles
Buds yellow and fall before they open
This is bud drop, and it almost always follows a dry spell or uneven watering rather than any disease. The plant is otherwise healthy, but it sheds buds when the root zone swings between wet and dry. Keep the soil evenly moist through bud set and hot weather, and lay down mulch to hold that moisture steady.
Fix:
- Maintain even soil moisture, especially during bud set and hot weather
- Mulch to conserve moisture and buffer soil temperature
- Avoid letting the root zone dry out completely while flowering
Spotted, blotchy leaves and the odd cankered stem
A handful of fungal leaf spots, blights, and rusts can mark the foliage, and canker fungi sometimes sink lesions into the stems. Wet weather and crowded, still air make all of it worse. Strip off the affected leaves, prune out any cankered wood, and open the plant up so air moves freely and the foliage dries fast.
Fix:
- Remove and dispose of affected leaves and prune out cankered stems
- Improve air circulation and avoid overhead watering
- Apply a labeled fungicide only if problems are severe
Toxicity
Good news for households with pets and children: Rose of Sharon is non-toxic across the board. The ASPCA lists it as safe for cats, dogs, and horses, and the flowers are even edible for people. Plant it anywhere without a second thought.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Safe around cats. A cat that nibbles a leaf or flower might get a brief upset stomach from the roughage, nothing more.
Dogs None
The ASPCA lists it as non-toxic to dogs, so a curious chew is no cause for alarm.
Horses None
Non-toxic to horses as well. Grazing on a few leaves carries no special risk.
Rabbits Safe
Rabbits can browse the foliage without harm, though any sudden change in diet is best kept small at first.
Livestock Safe
No toxins of concern for cattle, goats, or sheep that wander past a planting.
Birds Safe
Backyard and wild birds are fine around it, and many visit the flowers for nectar.
People Safe
Safe for people, and the flowers are even edible, eaten raw in salads or steeped into tea.
No special handling precautions for toxicity; as with any plant, ingestion of large amounts of plant material may cause mild, transient stomach upset.
Varieties
Breeders have given Rose of Sharon a wide range of flower colors and forms, from clean singles to ruffled doubles. These are the named selections you'll run across most often.
Diana
Carries pure white single flowers that stay open into the evening, and as a sterile triploid it sets almost no seed.
Blue Bird (Oiseau Bleu)
Stands out for its large single flowers in true violet-blue, each one centered with a red eye.
Minerva
Blooms in soft lavender-pink with a reddish-purple eye at the throat.
Aphrodite
Bears dark pink single flowers marked by a deep red center.
Red Heart
Shows crisp white petals around a prominent red center.
Lavender Chiffon
Opens lavender semi-double, anemone-form flowers with an extra ruffle of inner petals.
How to propagate
There's more than one way to make new plants, and the method you pick decides whether the offspring matches the parent. Cuttings and layering keep the flower color true, while seed is a gamble worth taking only if you don't mind a surprise.
Stem cuttingsEasy
Softwood cuttings in late spring to summer; hardwood cuttings in late fall to winter · Several weeks to root; transplantable the following season
Cuttings are the surest way to copy a plant, since they hold the parent's exact flower color. Take softwood cuttings in late spring or summer, or hardwood cuttings from late fall into winter, and they root over several weeks. Grow them on and they're ready to move the following season.
SeedEasy
Sow late winter to early spring; the species also self-seeds outdoors · Germinates in a few weeks; flowers in 2-3 years
Seed is easy but slow, and the seedlings rarely match the parent's flower color. Sow from late winter to early spring and the seeds sprout in a few weeks, but a new plant takes 2 to 3 years to flower. The species also self-seeds freely outdoors, sometimes more freely than you'd like.
LayeringEasy
Spring to summer · One growing season to root before separating
Layering is the hands-off method. Bend a low branch down to the soil in spring or summer, pin it in place, and it grows its own roots over one season before you cut it free as a separate plant.
Myths
Rose of Sharon is poisonous and dangerous to dogs and cats.
The ASPCA classifies Hibiscus syriacus as non-toxic to dogs, cats, and horses. A pet that nibbles a leaf or flower is in no danger, and the flowers are even edible for people. The most you might see is a brief stomach upset from eating a lot of any plant material.
Prune Rose of Sharon in fall or summer to get more flowers.
It blooms on new wood, the growth it puts on in the current season, so cutting it back in summer or fall removes the very stems that would have flowered. Prune in late winter or early spring before growth begins, and cutting back to 2 or 3 buds gives you fewer but larger blooms.