The Blue Chiffon rose of Sharon is an excellent flowering shrub offering blue color in late summer and early autumn when many shrubs have long ceased blooming. These blooms have white stamens surrounded by clusters of smaller, blue inner petals that give these hibiscus flowers a frilly or "double" appearance. The flowers—Blue Chiffon being the registered trademark of this specific rose of Sharon—appear only bluish, at best, when fully open, but closed blooms appear more vibrant.
Plant new shrubs in the spring or fall about 2 to 3 feet apart for adequate room. Rose of Sharon grows at a medium rate of about 1 to 2 feet per year.
|Common Name||Blue Chiffon rose of Sharon, shrub althaea|
|Botanical Name||Hibiscus syriacus|
|Mature Size||8-12 ft. high|
|Sun Exposure||Full to partial sun|
|Soil Type||Prefers loamy with humus|
|Soil pH||Alkaline, neutral|
|Flower Color||Shades of violet-blue|
|Hardiness Zones||5-9 (USDA)|
|Native Area||China, India|
Blue Chiffon Rose of Sharon Care
With its blue hibiscus flowers, this bush is attractive enough to be used as a specimen. You can also plant several of the shrubs together along a border to form an ornamental hedge. However, because it is a deciduous shrub it makes an effective privacy hedge only in summer when it has leaves.
Mulch the shrubs for weed control and to maintain moisture in the soil. The bushes are fairly tolerant of dry conditions once established. In fact, yellowing leaves on althea can be an indication of too much water rather than too little.
Grow these plants in full sun to partial sun. Plant the shrubs where they will receive a minimum of four to six hours of direct sunlight every day. In warmer climates, rose of Sharon prefers lots of morning sun with protection from harsh afternoon rays, but will likely tolerate a bit of overheating.
Rose of Sharon prefers well-drained, loamy soil enriched with humus. This plant is tolerant, however, of many types of less-than-perfect soil and polluted surroundings, which makes it a good urban garden planting. After planting a shrub, add a layer of mulch to help keep the soil moist.
The shrub requires a lot of water until they are established, and then the plant is drought-tolerant. Water deeply to soak roots on established plants but don't water again until the top of the soil is completely dry.
Temperature and Humidity
Though rose of Sharon is related to the tropical hibiscus, it tolerates a wider range of temperature and humidity conditions. It handles southern heat and northern cold better than other tropical outdoor plantings. Rose of Sharon can grow in cooler zones than the typical hibiscus plant, which makes this an attractive shrub. The plant is known to tolerate temperatures as cold as 20 degrees Fahrenheit below zero. It is tolerant of just about any humidity level, as well.
Rose of Sharon is not picky about its fertilizing needs. But don't overfertilize the plant or it will grow more leaves than blooms. When first planting the shrub, use a general-purpose, controlled-release fertilizer. Mix it into the soil that you are going to backfill the hole with to settle the plant. Give shrubs a meal of liquid fertilizer early to mid-summer to boost their blooms. Don't fertilize too late in the summer or you will encourage new growth during chillier temperatures which can be damaged by frost.
Since it is one of the shrubs that bloom on new wood, Hibiscus syriacus is normally pruned in late winter or early spring. Pruning often is not necessary, although you may choose to prune for shaping purposes or, on old shrubs, for rejuvenation.
You can train your rose of Sharon shrub into a small tree but it will take a few years to fully accomplish the look. To do this, remove weak stems and branches halfway up the shrub (and watch for thorns). Then, trim back upper branches to shape the canopy into a tree. Do not trim or prune more than a third of the upper branches or canopy when shaping your shrub. Keep on top of this method of shaping year to year.
Propagating Blue Chiffon Rose of Sharon
Rose of Sharon is easily propagated by taking stem cuttings, but gather more cuttings than you think you need because not all will successfully grow into viable plants. Seeds may not result in plants that look like the parent, but if you want a duplicate of the parent rose of Sharon plant, it's best to propagate with stem cuttings. Take cuttings in June or July as it begins to show its new growth. Take these steps:
- With a sterile and sharp cutting tool, take a few cuttings from new growth. Make sure the stems you cut are 4 inches long.
- Remove all but the top two or three leaves of the stem. Dip the bottom of each stem in rooting hormone.
- Fill a pot with soilless potting mix that you have premoistened.
- Insert the cutting into the mix and cover the pot with clear plastic (make sure the plastic is not touching the leaves).
- Put the container in the shade for about a week. After a week, remove the plastic.
- Begin to slowly move the container to full sun a few hours a day until it's in the sun all day. After about a month, you should see roots. Transfer your plants to larger pots and wait for fall to plant outdoors in a permanent space.
How to Grow Blue Chiffon Rose of Sharon From Seed
You once could harvest endless seeds from Blue Chiffon rose of Sharon shrubs. The shrubs would drop seeds and new plants would self-propagate. Breeders of the Blue Chiffon have fixed this seeding problem—it was veering towards invasive—and now there are seedless varieties that will not make a mess in the garden. But even if you can't find seeds, you can buy them. Seeds prefer to be planted in the fall.
Planting seeds outdoors:
- Choose a sunny spot with rich, fertile soil that is enriched with humus.
- Sow seeds about 1/2 inch deep and loosely cover seeds with soil.
- Deeply water newly planted seeds. Water every day until you see seeds sprout in two to four weeks. Cut back on watering to saturating the area two to three times a week until the frost arrives.
Planting seeds indoors:
- Fill small seedling pots loosely with soilless potting mix.
- Insert one seed per pot about 1/2 inch deep in the mix and loosely cover.
- Water once a day with water from a spray bottle. Gently mist the surface of the mix so the pot is saturated with water, but not soggy or overwatered. Do not let the mix become dry.
- Place seeds in a sunny spot, preferably one that stays at about 75 to 85 degrees Fahrenheit all day and night.
- Seeds should germinate in two to four weeks. If you plan to plant the seedlings outdoors, make sure it is the fall and 12 weeks or so before the first frost is due.
Potting and Repotting Blue Chiffon Rose of Sharon
Though rose of Sharon is more typically grown in the ground, it can look lovely as a potted plant on the patio with other smaller container plants. The plant, however, will grow large and heavy. and can be a chore to repot. You will need to repot your plant if the roots are growing out of the drainage holes of its existing container or it is getting top-heavy compared to the pot it's in. It's best to repot when the plant is dormant in the winter months (November through March).
- Choose any type of pot material, but always use containers with at least three large drainage holes. Choose a container that is the next size up from the current container, but do not go too large or the roots will expand and the shrub will grow very large and unwieldy as a patio plant.
- Add large rocks to the bottom of the container over the drainage holes so you don't lose any potting soil.
- Fill the pot a third of the way up with organic mulch, compost, and potting mix of peat moss and perlite to give the plant a mix of nutrients while allowing the roots to expand a bit.
- Gently coax the root ball out of its current container. Loosen dirt from the root ball so you can see if any roots need to be trimmed. Cut up to a third of the roots to keep the plant around its current size.
- Place the plant gently in its new container and fill soil mix around the root ball.
- Add slow-release fertilizer granules per the package's instructions.
- Deeply water the newly potted plant. Keep the soil moist but never soggy, until the summertime when it needs to be watered two to three times a week, unless the pot can be watered naturally by rainfall.
- Always keep the plant in full sun on your patio unless you live in southern zones where the plant will need protection from harsher afternoon rays.
You'll likely need to overwinter potted rose of Sharon plants. The pots, however, may contain large trees or shrubs. If you can't move the pots and you live in a cooler northern zone, wrap the plants to protect them.
In warmer southern zones, there's no need to prepare rose of Sharon for winter months. For outdoor rose of Sharon plants in cooler zones, protect the shrubs with a layer of mulch or straw. If you are in a colder climate with outdoor shrubs, protect the plants' crowns from cold and wind with a plant wrap.
Common Pests & Plant Diseases
These plants are susceptible to leaf spot and canker, both of which can be dealt with by removing infected parts before the disease spreads (if you spot the problem soon enough).
Does the rose of Sharon attract wildlife?
What's the difference between the Blue Chiffon rose of Sharon and the Blue Satin rose of Sharon?
The two plants have similar registered trademarks but the blooms look different. Blue Chiffon's blooms are more delicate and frilly, with a "double" appearance, while Blue Satin's flowers are usually less frilly, deeper blue with a hint of magenta, and punctuated with prominent yellow stamens.
Are rose of Sharon and dinner plate hibiscus the same?
Common names of both plants are often confused and they are part of the same Malvaceae family but they are different. Rose of Sharon is a bushy, woody shrub with small to medium blooms. Dinner plate hibiscus is a hardy hibiscus with eye-popping flowers the size of, well, dinner plates.
Can Blue Chiffon rose of Sharon be grown indoors?
Rose of Sharon typically does not make a good houseplant. One reason is that it grows into a large and heavy shrub or tree (when trained). But it also requires a lot of sun and indoors it would simply block any window and never get an adequate amount of light, anyhow.