Keep Your Bougainvillea Plants Healthy All Winter With These Simple Tips

The bougainvillea (Bougainvillea spp.) is a glorious genus of tropical plants that can flower throughout much of the growing season, climbing over trellises or over rock walls, and covering everything with spectacular blooms. It is among the best plants to grow in USDA hardiness zones 10 and 11. With protection from frost and cold, bougainvillea can be grown in zone 9, as well. If you'd like to keep your bougainvillea healthy through the winter, however, your best solution is to grow it in a container and move the plant indoors. But since bougainvillea is a vigorous grower, bringing a mature plant indoors can be difficult, if not impossible. You can still protect the plant outdoors in winter by covering it, assuming your area doesn't experience a deep freeze. 

Keep in mind that bougainvillea doesn't establish deep root systems that reach to where the ground doesn't freeze. If temperatures drop below 40 degrees Fahrenheit overnight, you risk losing your plant. If you live in an area that doesn't receive hard freezes, you can either grow your bougainvillea in the ground or in pots that you leave out all winter. Just remember that potted plants are even more exposed to the cold than plants grown in the ground, so they may need more protection. The key is to let your plant go dormant without letting it freeze. Like many other plants, your bougainvillea does need a rest during the colder months, so winterizing it won't deprive you of abundant blooms. The plant will stop flowering and even lose its leaves when it goes dormant, so you are not missing out on any splendor in winter anyway.

When temperatures reach into the low 50s in your area, it's time to take action. If you're leaving your plants out for the winter, the first step is to cut back the canes after the leaves have dropped to put less strain on your plant. One of the main joys of bougainvillea is its sprawling nature, so cutting it back may feel like you are sacrificing a year's worth of beauty, but remember that the plant will return to its vigorous ways once it begins growing again. Once cut back, cover the soil around the plant with a loose layer of mulch 3 to 5 inches thick and water thoroughly before the first frost. Store your potted plants in a place protected from the wind and near a heated building or stone wall that can reflect the sun's warmth. If temperatures approach freezing or below, you can wrap your outdoor plant with a breathable material that you leave on for the winter. 

If your area expects hard freezes, it's best to grow your bougainvillea in a pot and bring it inside for the winter. Remove any dead leaves and cut the canes back to reduce strain. Once that's done, keep your potted bougainvillea in a sunny garage or basement that doesn't drop below 60 degrees Fahrenheit. Water it every three or four weeks so that it doesn't dry out, but since it's dormant, it doesn't need frequent watering or fertilizer. When spring arrives, you can encourage it to begin growing by watering it more frequently. If you see signs of growth in the form of green shoots, fertilize it with a DIY compost tea or other liquid fertilizer. Once the last frost has passed, you can move your plant back outside.