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Mandevilla vines produce masses of gorgeous flowers, and their bright green, glossy foliage looks beautifully lush. The one downside to Mandevilla plants is that they are very sensitive to cold temperatures and frost.
To grow Mandevilla as a perennial, it needs special care during winter. When nights get to under 50°F (10°C), prune your Mandevilla back hard, and bring it indoors. Place it indoors in a warm spot where it gets bright light. Water it very lightly when the soil feels dry, and do not fertilize it.
Mandevillas can be quite finicky plants, but once you are familiar with the care they need, especially during the winter, they will grow and flower prolifically. Here is the ultimate guide to successfully winterizing your Mandevilla.
Can I Leave My Mandevilla Outdoors in the Winter?
Mandevillas are native to tropical and subtropical regions of the Americas. Therefore, they are adapted to growing in warm climates with mild winters.
If you live in USDA hardiness zones 9, 10 or 11, you can happily leave your potted Mandevilla vine outside over winter.
However, due to their sensitivity to cold and frost, if you live outside these growing zones, it is essential to move your Mandevilla indoors when temperatures start dropping. It is best to grow them in a container rather than in the ground.
If you live somewhere with cool but frost-free winters, you can take a gamble and leave your Mandevilla outside. Prune it right back and place a plastic bag over the top to protect it.
Successfully Overwinter a Mandevilla Vine Indoors
Winterizing a Mandevilla is not quite as simple as bringing it inside and treating it like any other houseplant. These fussy vines require special treatment right before, during, and after winter to keep them growing healthily.
What Is the Coldest a Mandevilla Can Handle?
Because Mandevillas are tropical and subtropical plants, they do not enjoy the cold. They will not tolerate temperatures below 45 to 50°F (7 to 10°C), but you should not wait for the mercury to drop this low before you bring yours inside.
When temperatures drop below 60°F (15°C) it is time to bring your Mandevilla indoors. Keep it in a sunny room that stays above 55 to 60°F (12 to 15°C).
If Mandevillas are exposed to frost or extremely low temperatures, they can die.
Prune a Mandevilla Before Winter
Mandevillas enter a state of dormancy during winter. Their growth rate grinds to a halt, they stop flowering, and their leaves will yellow and drop.
It is important to prepare your Mandevilla for its winter dormancy by giving it quite a drastic prune. They are resilient, fast-growing plants that will bounce back from the most aggressive pruning.
Mandevillas are large vining plants, and not many people have enough space in their homes to accommodate them. Pruning the plant will keep it a manageable size.
It is vital that you use sharp, sterile pruning shears on your Mandevilla. This will prevent the cuts from becoming infected.
Thoroughly check your Mandevilla vine’s foliage for pests before bringing it inside. Place it in a basin and run water through the soil until it is thoroughly flushed. This will get rid of any pests lurking in the soil.
Cut it down to around 10 inches (25cm) tall. Do not worry! Come spring, its growth will explode, and it will quickly reach its original size.
How Much Light Does a Mandevilla Need?
If you decide to keep your Mandevilla as an indoor houseplant during the winter, place it in a spot where it will receive bright, indirect sunlight.
Harsh, direct sunlight can scorch the leaves, so keep it in a spot that is sheltered from the hot, afternoon sun.
In actual fact, Mandevillas do not require any light when they enter dormancy. Some gardeners winterize their Mandevillas in the garage or basement.
To get your Mandevilla into a completely dormant state, prune it back to about a foot tall, and leave the plant outside until it reaches around 50°F (10°C).
Do not let your Mandevilla freeze, or it will die instead of going dormant!
Place a dark plastic bag over the plant and place it in the basement or garage, away from any sunlight. By depriving it of light, you help the plant remain in a completely dormant state.
During the winter, check on your Mandevilla occasionally and check the soil moisture. If it gets dry, give it a little bit of water.
How Often to Water a Mandevilla During Winter
Mandevillas grow extremely slowly during winter, if at all. Therefore, the plant does not use a lot of water during the colder months of the year.
Your Mandevilla will require much less frequent watering in winter than during the growing season. As a general rule, you should cut watering in half during its winter dormancy.
Feel the soil moisture using your finger on a weekly basis. If the soil feels very dry, give it a light watering.
You want to keep a Mandevilla moderately dry while it is dormant. The soil needs to stay just moist enough to maintain a healthy root system.
Does a Dormant Mandevilla Need Humidity?
Even though it is recommended to keep a Mandevilla on the dry side during winter, these plants still require some humidity while they are dormant.
Excessively dry air from an air conditioner will turn these plants crispy. It is a good idea to use a humidifier during the winter, especially if you heat your home.
Fertilizing a Mandevilla During Winter
Mandevillas require regular feeding during the growing season, but during winter, they should not be fertilized. When they are not actively growing, they do not take up nitrogen, potassium, and phosphorus.
Even if your Mandevilla shows signs of new growth while it is living indoors, avoid the urge to feed it! Any new winter growth will die back when you take it outdoors in spring anyway.
Wait until early spring before fertilizing your Mandevilla.
Helping a Mandevilla out of Winter Dormancy
Early in spring, when temperatures get warmer and the sunlight gets brighter, you should start to see some signs that your Mandevilla is coming out of dormancy.
This is a great time to repot it into a larger container and refresh the potting soil. Add some compost, leaf mold, and coco peat to the potting mixture.
Place the plant in a warm, sunny, humid environment. A greenhouse is ideal, but a sunroom or large window is great too.
Water it generously, and then continue to water it as usual when the top few inches of soil feel dry to the touch. The soil should stay slightly damp but not soggy.
Feed the plant every two weeks with an organic liquid fertilizer. Dilute it to half-strength. This will give it the nutrients it needs to burst to life.
On sunny, warm days, put your Mandevilla outdoors but take them back indoors at night when the temperature drops. This will help it acclimate to growing outdoors.
When daytime temperatures consistently stay above 60°F (15°C) and it doesn’t get colder than 50°F (10°C), you can safely move your Mandevilla outside full-time.
Tips for Caring for a Mandevilla in the Growing Season
To keep your Mandevilla vine growing healthily and flowering profusely, it needs at least 6 hours of sunshine. It is best to grow them in a spot that gets good morning sun but is sheltered from the harsh afternoon sun.
You can grow them in the ground (it is a beautiful floral groundcover), but an advantage of growing it in a pot is that you can move it to the optimal growing conditions and move it out of intense sunlight, so the leaves won’t get scorched.
Mandevillas can certainly be grown as houseplants. They are beautiful, lush vines. However, they seldom flower indoors because they usually don’t get enough light. They may flower if they are grown in a sunroom or in a sunny window.
Mandevillas thrive in sandy soil with lots of organic matter. The soil needs to drain well so that the roots never sit in saturated soil for prolonged periods.
Mandevilla plants enjoy growing in soil that stays a little moist all the time. They can tolerate the soil drying out for short periods (it won’t affect the flowering drastically) but prefer moist roots.
Water your Mandevilla about once a week during the growing season. The length of your watering cycle depends on your climate, though, so pay attention to signs that your Mandevilla needs water.
Use a soil probe or simply your finger to check that the top few inches of soil are dry before you water. This will prevent overwatering and root rot.
Take your time to water a Mandevilla. Water is slowly so that the soil has time to soak up the moisture.
To keep your Mandevilla free of insect pests, spray the leaves regularly with water. This will knock pests off the leaves. It will also help to keep the foliage dust-free.
Scale, whiteflies, aphids, and red spider mites are often attracted to new growing shoots. You may notice the leaves looking damaged or discolored and see little bugs crawling on your Mandevilla.
Thankfully, these pests are not difficult to deal with. Soak a cotton bud in rubbing alcohol and wipe the bugs off the leaves and shoots. Spray the plant with neem oil once a week until you see no more pests.
Frequently Asked Questions
- How big do Mandevillas grow?
Naturally, these plants have a vining growth habit. They can grow between 3 and 10 feet tall in a container with a trellis or support structure. To keep the growth more compact and encourage it to become bushier, simply pinch the stems back.
- Why is my Mandevilla vine not flowering?
A Mandevilla needs enough sunlight to flower. When you grow these vines as houseplants, they seldom flower unless you grow them in a sunroom where they get 6 to 8 hours of sunlight daily. Fertilize your Mandevilla every two weeks with an organic fertilizer that is high in phosphorus – a nutrient they need to bloom.
- How often does a Mandevilla need to be repotted?
They are fast-growing plants, so Mandevillas need repotting every year in spring. Ensuring they have enough room in their pot keeps them growing healthily and flowering well.
- How do you propagate Mandevilla?
You can easily propagate Mandevilla from stem cuttings, but you can only take cuttings from mature plants that have bloomed for a season already. The best time to take cuttings is spring. Use sharp, sterile scissors to take 5-inch-tall cuttings, making the cut below a leaf node. Snip off the buds and lower leaves and dip the cuttings in rooting hormone. Plant the cuttings in potting soil and keep them evenly moist and in a warm spot with indirect light. They should develop roots in 4 to 6 weeks.
- Are Mandevillas toxic? Be careful when pruning these plants or pinching off growing tips with your fingers. The milky sap is toxic if ingested, and it irritates your skin. Wash your hands directly after pruning.
Even though Mandevillas require some special care during winter, these plants are relatively easy to grow indoors or outdoors in a pot or hanging basket. Healthy Mandevillas are so rewarding because they produce masses of white, red, or pink flowers all year round.
When they are grown indoors, they do not flower, but they do produce luscious, fast-growing vines that bring a tropical jungle atmosphere. Growing them in a container is best so that you can move them to a warmer or sunnier spot.