How to Grow and Care for 'Blue Chiffon' Rose of Sharon

The 'Blue Chiffon®' Rose of Sharon (Hibiscus syriacus) is an excellent flowering shrub offering the elusive pale blue color in late summer and early autumn when many shrubs have long ceased blooming. The blooms have white stamens surrounded by clusters of pale lavender-blue petals with a small burgundy blotch at their base that give these hibiscus flowers a frilly and lacy appearance. The flowers—'Blue Chiffon' being the registered trademark of this specific Rose of Sharon—are blue when fully open, but closed blooms appear more vibrant.

Plant these shrubs in the spring or early fall about two to three feet apart for adequate room. 'Blue Chiffon' is sterile and will not self-seed. It grows at a medium rate of about one to two feet per year. Deer are not likely to severely damage this plant but pollinators love it.

'Blue Chiffon' Care

With its blue hibiscus flowers, this shrub is attractive enough to be used as a specimen plant. You can also plant several of the shrubs together to form an ornamental hedge. However, because it is deciduous and drops its leaves in the fall and doesn't leaf out again until late spring, it makes an effective privacy hedge only in summer.

Mulch the shrubs for weed control and to maintain soil moisture. The bushes are fairly tolerant of dry conditions once established. In fact, yellowing leaves can be an indication of too much water rather than too little.

Light

Grow these shrubs in full sun. Plant the shrubs where they will receive a minimum of six to eight hours of direct sunlight every day. In warmer climates, rose of Sharon prefers morning sun with protection from harsh afternoon rays, but they will likely tolerate a bit of overheating.

Soil

Rose of Sharon prefers well-drained, loamy soil enriched with humus. However it tolerates many types of less-than-perfect soil and polluted surroundings, which makes it a good plant for urban gardens. After planting, add a layer of mulch or finished compost to help keep the soil moist.

Water

This shrub requires consistent weekly watering until it is well-established. Water deeply to soak roots but don't water again until soil surface is dry. this shrub dislikes extremes and won't grow well in soil that is constantly wet or constantly dry.  Mature plants are drought tolerant.

Temperature and Humidity

Though rose of Sharon is related to the tropical hibiscus, it tolerates a wider range of temperatures and humidity than its tropical cousins. It handles southern heat and northern cold better than other outdoor tropical plants. Rose of Sharon can grow in cooler zones than the typical hibiscus plant, which makes this an attractive shrub for gardeners in colder regions, as cold as USDA hardiness zone 5. This shrub is known to tolerate temperatures below zero Fahrenheit. It is tolerant of just about any humidity level, as well.

Fertilizer

Rose of Sharon is not picky about fertilizing. But don't overfertilize the plant or it will produce lush foliage at the expense of blooms. When first planting , use a general-purpose, controlled-release fertilizer. Mix it into the soil from the planting hole. Give shrubs a meal of liquid fertilizer in late spring to early summer to boost their blooms. Don't fertilize too late in the summer or you will encourage new growth which can be damaged by frost.

Pruning

Because it blooms on new wood (this year's new stem growth), prune the rose of Sharon in late winter or early spring before new growth emerges. Pruning often is not necessary, although you might choose to prune for shaping, to maintain a specific size, remove dead or damaged branches, or to rejuvenate older shrubs.

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. Then, trim the 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. Continue 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 develop into viable plants. Seeds might not result in plants that look like the parent, so 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 generate new growth long before the first fall frost. Here's how:

1. With a sterile and sharp cutting tool, take a few stem cuttings from new growth. Make sure the stems are about four inches long.
2. Remove all but the top two or three leaves from the stem.
3. Dip the cut end of each stem in rooting hormone.
4. Fill a pot with soilless potting mix that has been premoistened.
5. Insert the cut end into the soil mix and cover the pot with a clear plastic bag secured with a rubber band (make sure the plastic is not touching the leaves).
6. Place the container in a shady location for a week.
7. Remove the plastic bag after a week has passed.
8. Harden off the cuttings to prepare them for life outdoors. Begin by slowly moving the container to outdoors to a sunny location, an hour at first and gradually increasing its daily sun exposure until it can tolerate full sun, six to eight hours per day.
9. After about a month, a root system will develop. Transfer the stem cuttings to larger pots and wait until fall to plant outdoors in a permanent space.

How to Propagate 'Blue Chiffon' Rose of Sharon From Seed

You once could harvest an endless supply of seeds from rose of Sharon shrubs. The shrubs would self-seed readily and unwanted new plants would spring up quite readily. Breeders of 'Blue Chiffon' have solved the self-seeding problem: it is sterile and does not produce viable seeds. So, if you want to propagate 'Blue Chiffon' from seed, you'll have to purchase the seeds and plant them in late spring so that the plants grow strong enough to survive the first fall frost.

Planting seeds outdoors

1. Choose a sunny spot with rich, fertile soil that is enriched with humus.
2. Sow seeds about 1/2 inch deep and loosely cover seeds with soil.
3. Water newly planted seeds every day until they germinate in two to four weeks.
4. Cut back on watering to two to three times per week until frost.

Planting seeds indoors

1. Fill small seedling pots loosely with soilless potting mix.
2. Insert one seed per pot about 1/2 inch deep cover lightly with soil.
3. Water once a day with water from a spray bottle. Gently mist the surface of the mix so the soil is moist, but not soggy or overwatered. Do not let the soil mix become dry.
4. Place seeds in a sunny spot, preferably one that stays at about 75 degrees Fahrenheit day and night.
5. Seeds should germinate in two to four weeks. If you plan to plant the seedlings outdoors, make sure it is 12 weeks or so before the first fall frost is due.
   

Potting and Repotting 'Blue Chiffon' Rose of Sharon

Though rose of Sharon is more typically grown outdoors in the ground, it can look lovely as a potted plant on the patio with other smaller container plants. This shrub, however, will grow large and heavy and can be a chore to repot. You will need to repot 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 best to repot when the plant is dormant in the winter months (November through March).

1. Choose a pot made of any material, but the pot should always have 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 grow rapidly to fill the pot and the shrub will grow quite large and unwieldy as a patio plant.
2. Use a porous landscape fabric or piece of window screening to cover the container drainage holes to prevent soil from washing out.
3. Fill the pot a third of the way with organic mulch, compost, and potting mix of peat moss and perlite to give the plant the nutrients it needs while maintaining proper soil aeration.
4. Gently coax the root ball out of its current container. Loosen soil from the root ball so you can see if any roots need to be trimmed. Trim up to a third of the roots to maintain the plant at its current size.
5. Place the plant gently in its new container and fill in with soil mix around the root ball, up to the top of the container.
6. Add slow-release fertilizer granules per the package's instructions.
7. Deeply water the newly potted plant. Keep the soil moist but never soggy, until the summer months when it needs to be watered more frequently.
8. Always keep the plant in full sun on your patio unless you live in a southern climate where the plant will need protection from strong afternoon rays.
   

Overwintering

In the northern end of its hardiness range, you'll likely need to overwinter potted rose of Sharon plants. However, after the growing season, the shrubs might have become quite large. If you can't move the pots and you live in a cold northern region of the United States, wrap the plants and containers to insulate them and move them to a sheltered location out of harsh winter winds.

In warmer southern regions, there's no need to prepare rose of Sharon for overwintering.

For rose of Sharon plants growing outdoors in garden beds in in the northern range of its hardiness zone, you can protect the root zone 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

Aphids and Japanese beetles commonly attack these plants. To control these pests, spray with neem oil for aphids and remove Japanese beetles manually and drop them into a bucket of soapy water.

These plants are susceptible to leaf spot and canker, both of which can treated by removing infected parts before the disease spreads (if you spot the problem soon enough).