Althea tree (Hibiscus syriacus), commonly known as the rose of Sharon, adds a dash of vibrant color to any home garden or landscape. This deciduous flowering shrub brags extravagant, tropical-looking blooms in shades of red, pink, purple, and white, and though it is native to India and China, it is hardy to U.S. Department of Agriculture zones 5 to 8.
Fortunately for amateur gardeners, it is relatively easy to care for althea trees.
How to Plant Althea Tree
Whether you choose to plant it in a pot, on a deck, terrace, or balcony, or directly in the ground in a flower and shrub bed, the Althea tree deserves special care upon planting to ensure it grows and blooms well.
Planting Althea Tree in the Open
Consider planting your tree in fall or spring if you have bought the shrub in a pot to a container.
• Select a sun-bathed area sheltered from strong winds
• Watering often during the first year after planting is crucial for Althea
• Follow our advice on planting shrubs
Planting Althea Tree in Pots
All year-round, the shrub must be planted in a soil mix designed for flowering plants, planting, or any universal soil mix.
• Althea requires a pot that is large enough; this will allow it to grow well as seasons come and go
• A bed of clay balls or gravel at the bottom of the pot will guarantee adequate drainage. This helps prevent roots from wallowing in sitting water at the bottom of the pot.
• The post must have a hole at the bottom for excess water to drain away.
• Repot in spring, at least once every second year (3 years is also okay), in a pot that is slightly bigger than the previous
Tips for Caring for Althea Tree
Althea trees can grow to a height of 8 to 12 feet tall with a spread of 4 to 10 feet. This plant flowers in late summer, so you can look forward to its beautiful blooms showing up in July and August and staying through the fall.
You can follow these important tips on caring for your althea tree:
• Water: A deep watering done once a week should be sufficient for the rose of Sharon. However, you may need to water it two or three times a week if it is newly planted. Monitor your plant carefully and avoid overwatering. The leaves of your althea tree may turn yellow in case you overwater.
• Soil: If you want the best bloom, plant your althea tree in well-drained soil. In fact, good drainage is necessary for the health of this plant.
• Fertilizer and mulch: You do not require fertilizer when planting althea. Nonetheless, it is recommended. Additionally, you can add a thick layer of mulch around the plant since this will retain moisture in the soil and protect the roots from freezing during winter.
How to Prune Althea Tree
You can prune your althea tree at the beginning of spring – towards February-March. Early spring pruning still offers the shrub time to produce flowers in the summer of that same year.
Althea blooms on new growth, so there is no harm in pruning it every year.
Nonetheless, try to avoid pruning late in the season since this would tend to reduce blooming.
Here is how you can prune your plant:
• Get rid of all branches that grow inwards so that the shrub can filter light through the inside.
• After that, cut the remaining stems back by around ⅔, just above an outward-facing bud. This means ⅓ of the branch remains on the tree.
Common Althea Tree Diseases and Control Methods
It is important to be aware of common diseases and pests that can afflict your althea tree. Although few pests affect althea (with the exception of nematodes), there are some common diseases that you should watch out for:
• Bud drop: Your althea tree is likely to suffer bud drop during the dry period. This is when open buds and flowers drop suddenly (when one moisture extreme follows another). You can provide your plant with sufficient water to avoid drought stress.
• Root-knot nematodes: This may show up as wilted or dried-up leaves. These nematodes cause knots to form on the underground roots of your plant. You can pull up all nematode-infested plants and destroy them after the season.
• Leaf rust: This is a leaf infection that presents as yellow-orange spots on the lower surface of the leaf. Fortunately, management and control of this infection are not necessary. You can focus on offering optimal growing conditions for your althea tree.
• Leaf spot: You can identify leaf spots from the circular spots that show up on leaves and cause the leaves to shed. To prevent it, use mulch and prune your althea tree to enhance air circulation.
