9 Key Tips for Overwintering Hibiscus Plants

If you want tropical-looking flowers that add an explosion of color to your garden, look no further than hibiscus. There are two types of hibiscus shrubs: tropical and cold-hardy. Tropical hibiscus are perennial shrubs that have colorful blooms throughout the year. Cold-hardy species are perennial shrubs that lose their foliage in the winter. 

If you live in Hardiness Zones 5-9, you’ll have no problems growing cold-hardy species such as the Texas Star Hibiscus outside. They naturally go dormant in the winter and require very little maintenance. However, to enjoy brightly colored tropical species such as roselle hibiscus and lion’s tail hibiscus, you’ll have to overwinter them. 

Aside from using a greenhouse, overwintering is the easiest way to help tropical species last through a frigid winter. Preparing to overwinter a hibiscus is easy if you follow a few guidelines. Below are the 9 key steps to overwinter your tropical hibiscus, so you get beautiful blooms each year. 

Sterilize Your Tools 

The first step to successfully overwintering any plant is sterilizing your pruning shears and other tools. This keeps harmful bugs, fungi, and diseases from coming into contact with your shrubs. 

Harmful pests can hitch a ride on garden tools and infect other plants in your garden. This is one of the easiest ways to spread diseases and infectious insects in your garden. You’ll be doing some serious pruning before overwintering your hibiscus, so this step is crucial. 

Fortunately, it’s easy to keep your tools clean and disinfected. You’ll want to clean each tool after every use. If you’re working on diseased plant material, go the extra mile by disinfecting them. Follow the steps below to keep your sheers and other tools ready for overwintering your hibiscus shrubs.

Steps to Clean Your Tools Like an Expert

• Remove all dirt, debris, soil, and leaves from your blades.
• Scrub off any rust with vinegar and a rough pad.
• Lather antibacterial soap and water onto your blades and scrub them with a clean sponge or cloth. 
• Spray a dissolvent such as this one to remove built-up sap and pesky stains.
• Dry them thoroughly, especially in hard-to-reach crevices. 
• If you’ve been working on diseased plants, disinfect your materials with 70% isopropyl alcohol or hydrogen peroxide. 

Start Pruning 

The second step to overwintering your tropical shrubs is pruning them before the temperatures dip below 50°F (10°C). Ahead of an approaching cold front, grab your sterilized pruning shears and start trimming each branch.

Use disinfected and sharpened high-quality pruners such as these to prevent infection and to cut cleanly. Cut them back to about a third of their size. Don’t cut off more than a third. Make your incisions above the branches’ last node.  

Take off dead or broken limbs and dead leaves. Crossing branches that cross or touch each other make your shrubs look crowded and hinder airflow. Give these a good chop and free up energy for new growth the following spring. 

Check for Diseases and Pests

Now that you trimmed back your shrub’s beautiful foliage, check for bugs or diseases. The last thing you want is to bring pests or diseases inside to infect your other houseplants. 

Look closely at the leaves and their undersides for whiteflies, one of these tropical plant’s most common pests. Inspect the branches, trunk, and topsoil. Check the containers as well for any critters hitching a ride. 

If you notice infections, you’ll have to cut off the diseased parts of your shrubs. Insects such as spider mites build webbing on the interior of your plants. As with most outdoor flowers and vegetables, look for aphids, and their telltale honeydew trails on the foliage or branches. 

Spray and Treat

After inspecting your shrubs for pests and diseases, it’s time to bring out the hose! Spray off every section of your shrubs to remove insects. Use a medium-powered shower attachment to spray the maximum surface area. 

Do this a few times a week until you bring your hibiscus indoors to overwinter. This will knock off pests and keep them off until you’re ready to bring your tropical beauties inside. 

If your tropical shrubs have fungal or bacterial diseases, you’ll want to treat them immediately. Diseases such as root rot are caused by overwatering and are harder to treat. Remove your flowering perennials from their containers, cut away infected roots, and replant them in clean soil. Always disinfect the containers after using them to prevent other plants from getting infected. 

Reduce Fertilizer

These tall flowers need a lot of food during their heavy blooming times in spring and summer. However, in winter, it’s best to cut the amount you feed them. Outdoor specimens will be fine without fertilizer in winter. 

Overwintered shrubs can benefit from a final feeding in the fall. Use food that’s rich in potassium and nitrogen. Potassium is an important nutrient for the overall health of these tropical flowers. 

Always follow your fertilizer’s directions and water when you feed. Consider diluting fertilizer strength with water. Overwintered hibiscus won’t need as many nutrients growing indoors. 

Move Them Indoors

Now it’s time to move your hibiscus indoors to overwinter in cozy warmth! Choose a warm location with bright light or direct sunlight. Keep them close to the sunniest window in your home, preferably facing the south or southwest. Make sure your plants are not touching windows that could become icy during the coldest months. 

Carefully move your pots inside. Make sure they’re away from areas with heavy traffic and other ornamental greenery they could cover with too much shade. Because they grow so full and tall, they’ll do well in living rooms or large kitchens. 

Bring your shrubs into a garage if it’s heated and has enough natural light. You can even use grow lights if your space doesn’t have adequate windows. For tropical species, the most important thing is to keep them away from extreme cold. Freezes will likely kill most tropical species. 

When They’re Thirsty, Water Them

When your flowers are indoors, they’ll still need a consistent watering schedule to thrive. Water them whenever the topsoil appears dry. Stick your finger into the top layers of soil. If you can’t detect moisture in the first layer, it’s time to water them. 

Although they like to be watered when thirsty, they don’t do well in soggy soils. Overwatered plants can develop soggy roots and, worse, root rot. This dreaded disease will kill your shrubs if you don’t remove the diseased roots and repot them. 

Stick to a consistent indoor watering routine to keep them hydrated and happy. Thirsty hibiscus will lose their energy and slowly die back. The foliage will turn yellow, wilt, and start dropping. If you see this, along with dry soil, water them more frequently. 

Check on Them Often 

An indoor hibiscus requires minimal basic maintenance to successfully overwinter. However, you’ll still want to check in on them and see how they’re coping with their new home. 

Moving them to a new environment can be shocking. Anything from a change in humidity, temperature, and sunlight location can stress these living decorations out. Signs of stress include discolored leaves and weak-looking foliage. 

If these signs are more extreme, it could mean there’s another issue. Extreme leaf dropping and color changes could mean your plant is getting too cold. If you suspect this is the case, use a thermometer to monitor the temperature around your plants. Move them a little further from cold windows or crank up the heat if you have to. 

Get Them Ready for Spring

When the birds return, the frosts cease, and the delicate buds break, you’ll probably want to bring your hibiscus out of hibernation. As exciting as this is, it’s best to hold off. Overwintered plants need to be re-introduced to the outdoors slowly. They’ve already become accustomed to the lower intensity of light and other aspects of living indoors. 

When the nightly minimum temperatures are well above 50°F (10°C), bring them out into a shady place. Keep them there for a week and monitor their growth. If they’re thriving, move them into a sunnier location for an hour at a time. Direct sunlight will shock the plants if you expose them immediately.

After they are accustomed to being outdoors again, you should notice vigorous new growth. This is a great time to fertilize your flowers using a formula rich in nitrogen and potassium. Spring is also a great time to repot your plants if they’re outgrowing their containers. 

Key Takeaways

Overwintering hibiscus is a good idea if you want to keep your tropical plants as annuals. This way, you’ll enjoy these brightly colored flowers for years to come. 
By following these top overwintering steps for hibiscus, your plants will not only survive the winter but thrive the next season. Enjoy your multicolored blooms until you’re ready to overwinter again.