Rose of Sharon shrubs are classified as hardy in USDA zones 5-8. Within those zones, they should overwinter easily, barring exceptional weather. If you are growing in zone 5 or 4, or expecting unusually cold weather, you may be wondering how you can help protect your plant to help it survive until spring?
Protecting Rose of Sharon in Winter
There are several steps you can take to help buffer your plant from the coldest temperatures and avoid winter burn or damage. You want to make sure your plant is hydrated, and properly covered or insulated from freezing winds.
Cutting Back Rose of Sharon for Winter
Roses of Sharon are deciduous shrubs, so will lose their leaves in fall. Pruning, usually done for shaping and improving air circulation, can be done any time between leaf-drop and bud break in spring. If you are concerned about rose of Sharon being hardy in your area, leave the pruning until late winter so there will not be fresh cuts open to the weather.
Rose of Sharon Winter Care in Pots
If you are growing a young rose of Sharon in a container, pot, or raised bed, it may need extra help in winter if you are in a colder hardiness zone. This is because containers offer less insulation around roots than open ground does. The smaller the pot, the less insulation. The younger the plant, the more vulnerable it is to cold temperatures.
A few inches of winter mulch will retain moisture and warmth at the plant’s roots. You can consider moving the pot, if it’s portable, against a sunny wall, whose reflected heat will radiate back onto the plant. If that’s not possible, wrap the plant with burlap, frost cloth, or bubble wrap. If using a non-permeable material like plastic, keep your wrapping open to the sky to allow air and rain in. For extra measure, chopped leaves can be used to fill the space between the pot and the wrapping. Some people make a temporary frame out of wire for this.
Watering Rose of Sharon in Winter
Whether in a pot or growing in the ground, it’s important to make sure your plant has enough water in its system before it freezes. Water thoroughly before an anticipated frost or cold spell. Mulching is helpful to hold warmth in the top layer of the soil.
Subsequent watering is only needed if the winter fails to supply rain and snow regularly, in which case, water when dry to two inches deep – an inch of water a week is a good rule.
Growing Rose of Sharon Indoors
Indoors is not a good option for growing Rose of Sharon. An unheated greenhouse or shed with sunny windows would be a last resort in the very coldest locations. Add protection like wrapping the pot if needed based on your area’s temperatures.
Steps to Care for Rose of Sharon in Winter
If you are growing within zones 5-8, winter preparation for roses of Sharon is simple. Pruning can be done now but if in a borderline hardiness zone, wait until the end of winter to prune. Mulch and water well before a frost hits. If growing in zone 5 or colder, especially in a pot, protect your plant with insulation and possibly move against a south or west facing wall.
Step 1 – Mulch the plant around the root ball with 2-3 inches of organic matter such as bark chips or compost.
Step 2 – Water well before a freezing event, and subsequently if the winter is dry.
Step 3 – Protect if your temperatures are near to or colder than -15 degrees fahrenheit – young plants and potted plants are most at risk. You can move the plant against a sunny wall, wrap in burlap or other breathable fabric, and surround it with chopped leaves.
Step 4 – Prune in late winter before leaf buds emerge.
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