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Rose of Sharon (Althea Shrub Plant) Grow & Care Guide

Written by Iris

Aug 11 2021

Rose of Sharon (Althea Shrub Plant) Grow & Care Guide
Rose of Sharon (Althea Shrub) is a hibiscus shrub or small tree that produces beautiful red, white, pink, light blue or lavender flowers. Many gardeners like Rose of Sharon because it produces amazing flowers when few shrubs bloom in late summer. It's also easy to take care of the salon plant's roses, which survive well through most winters. Rose of Sharon (Althea Shrub) is a great shrub to use as a privacy hedge or foundation shrub.

Where to Grow Rose of Sharon

Full sun to partial afternoon shade. An area with good air circulation Rose of Sharon produces the best flowers and strongest stems, and is the best environment to prevent disease. Keep an eye out for hot, scorching afternoon sun that may burn the foliage; as well as provide protection from damaging wind.

When to Grow Rose of Sharon (Althea Shrub)

If you are adding rose of Sharon shrubs to your garden, you should plant them in the spring or fall. Because they are a good hedge plant, plant them 6 to 10 feet (1.8 – 3 m) apart, depending on your landscaping goals. You can also grow rose of Sharon from seeds by planting the seeds outdoors in late winter about 12 weeks before the last frost date. They should be planted in sunny spots and require deep watering.
Rose of Sharon

How to Grow Rose of Sharon (Althea Shrub)

Grow Rose of Sharon from Seeds

It is easier to propagate from seed, however the offspring are not true to type. Harvest the seeds in fall just before they are fully mature and sow them directly into the planting bed outdoors. You can also store the seeds in a dry place over winter and sow them in spring. If so, soak the seeds in water for around 24 hours. Then sow the seeds into sowing substrate in a seed tray, lightly press into the soil using a board and sift a little sand over them. The seeds start to germinate after 4 to 10 days and can be pricked out into pots a few weeks later. After around three years, the young Rose of Sharon can be planted in the garden.

Grow Rose of Sharon from Cuttings

Rose of Sharon is propagated through cuttings. You can do so at any time of the year. But there are a few things you need to remember if you want to grow another bush in your yard. For instance, take green cuttings during summer and wooden cuttings in fall or winter. The wooden cuttings should be at least one year old. Aim for 4 to 6-inch cutting. All leaves except for the top ones should be removed.
If you are propagating the rose of Sharon in summer, you can take the fresh cutting and place it directly into the ground. The soil needs to be moist and fertilized. Keep watering the new plant frequently, and it should develop the root system in no time.
Generally, the safest way to propagate rose of Sharon is to place a fresh cutting into a pot. Use a rooting hormone on the bottom part of the stem and place the lower half into a pot. Water the cutting and cover it up with clear plastic.
The pot should be kept in shade or indirect sunlight. Remove the plastic after one week. Keep the soil moist but not too much. The root system will develop after one or two months. You can check by pulling the plant up. Also, if you see new leaves, the cutting is adapting and growing.
Rose of Sharon

How to Care for Rose of Sharon (Althea Shrub)

Rose of Sharon Lighting

Rose of Sharon will grow well in full sun or part shade. For best flowering and overall performance, we suggest a minimum of 6 hours direct sunlight.

Rose of Sharon Soil Care

Hibiscus Syriacus prefers well-drained clay soil that is rich in nutrients and humus, and not too dry. The substrate should be slightly acidic to alkaline. Poor, acidic sandy soils often result in weak flower formation and the shrub ages faster.

Rose of Sharon Watering

Rose of Sharon prefers moist soil, especially during spring and summer. Water it frequently to increase the number of flowers. On the other hand, too much water can damage the plant. If you notice that the leaves are turning yellow, it doesn't mean the plant needs more water. Instead, you have been overwatering it. Rose of Sharon is drought tolerant and can survive a short period without water. Rose of Sharon will not be harmed in any way. Return to your watering schedule, and the rose of Sharon will continue to grow, producing large and colorful flowers as usual.

Rose of Sharon Temperature & Humidity

A heat lover, Rose of Sharon is also prized by growers in the southeastern U.S. who seek plants that can stand up to summer's heat. Rose of Sharon is also tolerant of a wide range of humidity conditions.

Rose of Sharon Fertilizer

Rose of Sharon need a fertilizer high in potassium (K), low in phosphorus (P), and with a medium amount of nitrogen (N)—too much phosphorus will kill a hibiscus. Hibiscus also respond well to an organic fertilizer, and a good layer of compost once a year is generally sufficient. Don’t fertilize after July as this can push new growth that will be damaged by frost.

Rose of Sharon Pruning

Rose of Sharon flowers are produced on new wood, so prune in early spring to shape and reduce size. Pruning the shrub back to 2 to 3 buds per branch in spring encourages larger flowers. Remove dead, diseased, and injured branches any time.Although naturally multi-stemmed, Althea-Rose of Sharon can be trained through pruning (in late winter) to a single main trunk.

Rose of Sharon Pests & Diseases

Rose of Sharon  is susceptible to flower bud drop, which happens when soil moisture levels fluctuate widely. Regular watering helps prevent this. Leaf spot, a common fungal disease that affects althea, can be treated with a sulfur plant fungicide. Sulfur fungicides are available as a fine powder, which you dust over the leaves. You can also mix the dust with water at a rate of 3 tablespoons per 1 gallon of water and apply it with a garden sprayer. Apply the dust or spray every 10 to 14 days, as needed. Althea is relatively pest-resistant but it is sometimes bothered by aphids or spider mites. To control the pests, spray the plant with a ready-to-use insecticidal soap spray until all leaf surfaces are covered. Repeat every seven to 10 days, until the infestation is under control. Neither fungicides nor insecticidal soap should be used when temperatures are above 90 degrees Fahrenheit, or when the sun is shining directly on the plant. Wear eye protection, protective gloves, long sleeves, long pants and sturdy shoes when applying garden chemicals.
Rose of Sharon

Rose of Sharon Varieties

Rose of Sharon ‘Lil' Kim' is a dwarf rose of Sharon with red, purple or white blooms. It matures at 3 to 4 feet tall and wide. The leaves are small, so you see a lot of colorful blooms as opposed to foliage. The flowers often last up to three days, while most rose of Sharon blooms fade after just one day.
Rose of Sharon ‘Purple Pillar' rose of Sharon is a beauty with semi-double, purple-pink flowers with red throats. It tops out at 10 to 16 feet tall but only grows 2 to 3 feet across, so it's a good choice for narrow spaces.
Rose of Sharon  'Lavender Chiffon' rose of Sharon is striking with its semi-double, light purple petals marked with red veins. It grows 8 to 10 feet tall, so it can be used as a small tree; just leave the central leader and remove the other branches.
Rose of Sharon  'White Chiffon' rose of Sharon is a fine choice for a moon garden, where its pure white blooms, when planted with other light-colored flowers and foliage, will reflect the moonlight. It matures at 6 to 8 feet tall.
Rose of Sharon‘Blue Satin' Chiffon has nearly true-blue petals set off by yellow stamens and splashes of red in the flowers' throats. This nearly seedless variety is sometimes sold as 'Azurri Blue Satin' and reaches 8 to 12 feet in height.
Rose of Sharon

Rose of Sharon (Althea Shrub) FAQ

How big does a Rose of Sharon get?

The Rose of Sharon grows to a height of 8–12' and a spread of 6–10' at maturity.

What is the lifespan of a Rose of Sharon?

A cold-hardy, drought-resistant shrub, Rose of Sharon can productively produce blooms for 20 to 30 years.

Are rose of Sharon tree roots invasive?

However, Rose of Sharon can grow up to 12 feet high and can spread out, so rose of Sharon should not be planted close to septic tanks or drainpipes. Though Rose of Sharon's red, pink, white or purple flowers can be vibrant and beautiful, rose of Sharon is considered to be an invasive plant.