Hibiscus is a gorgeous tropical flower that adds vibrant color to gardens. However, it can be challenging to overwinter hibiscus plants in colder climates. With proper care and preparation, you can help your outdoor hibiscus survive the winter. Here is a comprehensive guide on protecting outdoor hibiscus in winter.
Choosing the Right Hibiscus Variety
When selecting hibiscus for your garden, choose cold-hardy varieties that can withstand your winter temperatures. Some good options include:
Hardy Hibiscus
These hibiscus varieties have large, showy blooms and can survive winter temps down to -30°F (-34°C). Popular cultivars are ‘Kopper King’, ‘Blue River II’, and ‘Pink Clouds’.
Rose of Sharon
Also known as Althea, Rose of Sharon is a rugged hibiscus shrub. It survives winters in zones 5-9. ‘Red Heart’ and ‘Aphrodite’ are two stunning varieties.
Tropical Hibiscus
Tropical hibiscus varieties like Hibiscus rosa-sinensis can live outdoors as perennials in zones 9-11. They make excellent container plants that you can overwinter indoors in colder zones.
Providing Winter Protection
Hibiscus need proper shelter from harsh winter conditions. Here are some effective techniques:
Insulate with Mulch
Spread 4-6 inches of shredded bark, compost, leaves, or other organic mulch around the base of the plant. This insulates the roots and prevents frost heave.
Wrap or Cover the Plant
Wrap hibiscus with burlap or a fuzzy plant jacket to protect from wind and cold. You can also construct a temporary cold frame around the plant using PVC pipe and plastic sheeting.
Use Heat Cables
Run special heating cables along the ground under the mulch. The gentle warmth prevents the soil and roots from freezing.
Install Burlap Screens
Secure burlap windscreens around hibiscus plants to shield them from frigid winter winds. Leave the top open for ventilation.
Build a Cold Frame
A DIY or purchased cold frame placed over potted hibiscus gives insulation while allowing light and air circulation.
Grow in a Greenhouse
An unheated greenhouse or hoop house maintains above-freezing temperatures to overwinter container hibiscus.
Providing Extra Winter Care
Along with physical protection, hibiscus also need some extra winter care and maintenance:
Water Sparingly
Water just often enough to keep soil slightly moist. Soil that stays wet during dormancy invites root rot.
Trim Back in Fall
Prune hibiscus in early fall by 1/3 to remove old wood and stimulate new growth. Don’t prune later as cuts may not heal before winter.
Fertilize with Care
Use slow-release feed or low-nitrogen fertilizer before dormancy. Avoid high-nitrogen fertilizers that spur tender growth prone to winter damage.
Check for Pests
Inspect regularly for pests like spider mites that can thrive in dry indoor conditions. Treat with horticultural oils or neem solutions.
Give Winter Sun
Place container plants in south-facing windows where they get maximum winter sunlight. Outdoor plants benefit from sunny spots too.
Monitor Soil Temperature
Use a thermometer probe to check soil temp around the roots. Avoid letting it drop below 55°F (13°C).
Bring Indoors if Needed
If temperatures plunge too low outdoors, bring container hibiscus inside to an unheated garage or basement until the cold snap passes.
Protecting Potted Hibiscus
Container-grown hibiscus need some extra coddling to get through winter:
Choose a Sheltered Spot
Place pots in a protected area of the garden away from wind. Up against the house or under trees works well.
Insulate the Roots
Wrap the container with bubble wrap or burlap. Place it inside a larger decorative pot lined with insulation.
Use Portable Heat
A mini greenhouse heater or outdoor heat lamps set on a thermostat provide warmth for outdoor container plants.
Overwinter Indoors
Bring pots into an unheated garage, basement, or enclosed porch for winter. Provide bright light and cool temps around 50-60°F (10-15°C).
Prune Away Dead Growth
In late winter, trim away any dead wood or damaged branches to make room for new growth.
Reviving Hibiscus After Winter
Once spring arrives, here are some tips for bringing hibiscus back to life:
Uncover Gradually
Remove winter protection slowly over several weeks as temperatures warm up. Watch for risk of late frosts.
Renew Mulch
Replenish the mulch around the plant, keeping a 2-3 inch deep layer. This retains moisture and suppresses weeds.
Prune as Needed
Trim back frost-damaged stems and shape plants. Cut just above healthy buds pointing outward for a fuller form.
Fertilize Lightly
Use a balanced fertilizer or one higher in phosphorus to stimulate good root growth and flowering.
Check for Pests
Inspect plants closely and take action against early-season pests like aphids before infestations take hold.
Water Thoroughly
Water hibiscus deeply as growth resumes. Add moisture-retaining mulch and provide supplemental water during dry periods.
Deadhead Spent Blooms
Remove faded flowers to improve the plant’s appearance and encourage further blooming.
With the right care, your hardy hibiscus will make it through winter ready to bloom again next year. Just be sure to select suitable varieties and provide protection from harsh cold and winds. A little extra attention goes a long way!
Common Problems Facing Outdoor Hibiscus in Winter
While hardy hibiscus can survive cold winters, they can still run into problems like:
Frost Damage
Sudden plunges into freezing temps can damage exposed shoots, buds, and leaves. Choose cold-hardy varieties and provide winter insulation.
Windburn
Desiccating winter winds can dry out and damage hibiscus foliage. Use screens and coverings to provide a wind break.
Root Damage
Alternating freeze/thaw cycles can heave plants from the ground. Mulch for insulation and avoid excessive moisture.
Pest Infestations
Spider mites, aphids, and scale bugs can build up on stressed winter plants. Apply horticultural oils or insecticidal soap.
Insufficient Light
Container plants moved indoors need bright southern light. Supplement with grow lights if needed.
Excessive Heat
For overwintered pots, cool temps around 50-60°F are vital. Avoid warm rooms and heat sources.
Lack of Humidity
Heated indoor air saps moisture from hibiscus foliage. Mist leaves or use a humidifier nearby.
Potted Plant Decline
Insufficient water, light, and humidity causes gradual weakening. Gently resume good care in spring.
With attentive care and proper protection, you can help your hibiscus remain healthy through the winter months.
Winterizing Potted Hibiscus Step-by-Step
Follow this step-by-step guide for overwintering container hibiscus plants:
Choose a Sheltered Outdoor Spot
Place the potted hibiscus in the most protected area of your garden, patio, or balcony. Up against the house out of wind works well.
Check the Roots and Repot
Examine roots and ensure the plant is not pot bound. Repot in fresh soilless mix enriched with compost or worm castings if needed.
Prune Back Overgrown Plants
If your hibiscus has become leggy or overgrown, prune it back by 1/3 to shape and stimulate new growth. Always cut just above buds.
Add Insulating Materials
Wrap the container with 2-3 layers of burlap or bubble wrap. Place it inside a larger decorative pot lined with soft insulation.
Install a Physical Barrier
Construct a simple enclosure around the pot using flexible stakes or PVC hoops and a breathable plastic film.
Use a Cold-Hardy Variety
Choose a winter-hardy hibiscus variety rated for your zone like Hibiscus moscheutos or Rose of Sharon. Avoid tropical varieties.
Water Sparingly Before Frosts
Allow the soil to dry out somewhat before bringing the plant inside. Excess moisture invites diseases.
Monitor Light Levels
Once indoors, ensure the plant gets plenty of bright light from a south or west window. Supplement with grow lights if needed.
Maintain Cool Temperatures
Keep indoor temperatures around 50-60°F (10-15°C) for overwintered hibiscus. Avoid excess heat from appliances or pipes.
Provide Gentle Air Circulation
Run nearby fans on low speed to prevent mold and fungus growth on leaves. Avoid hot blasts of heat or AC.
Check Soil Moisture Weekly
Water only when the top few inches of soil become dry. Hibiscus needs less frequent watering when dormant.
Watch for Pests
Check undersides of leaves for spider mites or scale. Wipe leaves with neem oil or insecticidal soap if infestations are found.
Storing Tender Hibiscus Plants Over Winter
Tropical hibiscus varieties like Hibiscus rosa-sinensis require specialized winter storage:
Cut Back Leggy Growth
Prune plants by 1/3 to reduce leaf loss and prevent breakage. Discard bug-infested or diseased stem trimmings.
Root Prune for Compactness
Carefully trim back the root ball by 1/3 with a sterilized knife or pruning shears if roots are congested.
Choose a Warm, Bright Spot
Find an indoor area heated to 60-70°F with southern sun exposure or ample grow lights.
Monitor Soil Moisture
Water whenever the soil dries out an inch below the surface. Take care not to overwater dormant plants.
Maintain High Humidity
Cluster pots together and mist frequently to provide needed humidity of 50-70%. Use a humidifier if dry indoor air is an issue.
Clean Plants Thoroughly
Inspect closely and wash leaves to remove dust, salt buildup, and insect eggs. Pay extra attention to leaf undersides.
Apply Protective Fungicide
Use a copper-based fungicidal spray to protect against diseases in winter confinement.
Avoid Disturbing Roots
Keep plants in the same pots with the old soil if possible. Repotting at this time risks traumatic root damage.
Fertilize Cautiously
Use half-strength balanced liquid feed every 4-6 weeks at most to avoid spurring tender growth prone to dropping.
FAQs About Protecting Hibiscus in Winter
Can you leave hibiscus outside in winter?
- Hardy hibiscus varieties can remain outdoors with proper insulation like deep mulching. Potted tropical hibiscus and less cold-tolerant plants need winter protection.
What temperature do hibiscus plants need in winter?
- Outdoor hardy hibiscus tolerate winter temps down to 10-20°F (-12 to -7°C) depending on the variety. Indoor hibiscus kept dormant need consistent cool temps around 50-60°F (10-15°C).
How do I prepare my hibiscus for winter?
- In fall, prune back leggy growth, treat for pests, overwinter in sunny indoor space kept cool and moderately moist. Insulate pots and amend soil if needed. Shelter outdoor plants.
Should hibiscus be cut back for winter?
- Yes, pruning hibiscus by 1/3 stimulates new growth and removes old wood. Cut back leggy branches just above outward facing buds. Time it in early fall so cuts seal before cold weather.
Does hibiscus need sun in winter?
- Hibiscus requires maximum sunlight through winter to stay healthy. Outdoor plants benefit from a sunny sheltered location. Indoor plants should be placed right next to south-facing windows.
Can you grow hibiscus indoors in winter?
- You can successfully overwinter many varieties of container hibiscus indoors. Provide lots of sun, moderate watering, cool temps around 50-60°F, and humidity. Watch for pests like spider mites.
What causes hibiscus leaves to turn yellow in winter?
- Yellowing leaves can indicate too much moisture, low light, pests, or decline from incorrect dormancy conditions. Improve drainage, increase sunlight, treat pests, and ensure proper winter care.
How do I keep my potted hibiscus alive in winter?
- Move pots to sheltered area, wrap in insulation, maintain 50-60°F, water when partly dry, provide ample sun, monitor for pests, avoid repotting, and fertilize lightly to keep dormant plants healthy.
When should I prune my hardy hibiscus?
- Prune hardy hibiscus varieties like Rose of Sharon in early spring before new growth emerges. You can also do light pruning after flowering in summer and heavier pruning in early fall.
Conclusion
Although hibiscus prefer warm tropical climates, many varieties can survive cold northern winters with proper care. Focus on choosing cold-hardy cultivars suitable for your climate zone. Site hibiscus plants in sheltered garden locations. Insulate the roots from frost and wrap or cover plants to protect from winter winds. Water sparingly just to prevent desiccation. Indoor potted hibiscus require bright sunny windows, cool temperatures, moderate humidity, and vigilance against pests. With the right preparation and winter protection, your hibiscus can return to their full glory come spring.