How to keep a mandevilla blooming

Posted in Gardening Tips on October 7 2011, by Sonia Uyterhoeven

For answers to some of the questions that have been left in the comments see this follow-up post.

Ed. note: Earlier this week I went for a walk in the Conservatory courtyard and spotted a beautiful Mandevilla vine growing vigorously in a container. I tweeted a picture of it, and almost immediately we got a reply from Twitter-user Jacqueline Lewis asking what is the best method for over-wintering this beautiful vine. It seemed like a really good question, so I put it to Gardener for Public Education, Sonia Uyterhoeven. Her answer is below. ~ A.R.

Both the species and the cultivated variety love light and good drainage. Wait until it starts to dry out before you water. Fertilize your mandevilla every other week with a liquid fertilizer when it is actively growing. Unlike many tropical plants, mandevilla does not like to be pot bound so give it room to grow.

Mandevilla are not hardy in our area, USDA Zone 6, so you have two options if you would like to over-winter your vine. The first option is to bring it into your home. If you have enough space and a bright sunny window then move the container inside once the weather starts to cool down.

Sometime in February, give the plant another good pruning and begin to fertilize it once a month. Mandevilla flowers on new growth. By pruning and fertilizing the plant, you are working to give it an early start so that when you place it outside in May or June it will take off and soon be covered with flowers. If you are growing a mandevilla in your home, it is a good idea to lower your thermostat to somewhere in the 60s or low 70s, otherwise it may get too dry.

The second option for over-winter your mandevilla is to allow it go dormant. Keep the vine outside until it gets nice and cool and then move it into a cool garage or basement that maintains a winter temperature above freezing, around 50?F is ideal. In this scenario you should cut the plant back hard, to about 12 inches. Occasionally give it water so that it doesn’t dry out, but essentially leave it alone. Bring it inside when spring is just around the corner and let it start to grow. Then set it outside and enjoy this beautiful plant throughout the summer. Good luck!

By SF Gate Contributor Updated October 28, 2020

Mandevillas (Mandevilla spp.) are tropical vines that produce showy trumpet-shaped flowers. Vines in this genus are generally hardy in U.S. Department of Agriculture plant hardiness zones 9 through 11, although some mandavilla species vary slightly. For example, Mandevilla boliviensis and Mandevilla amabilis, a mandevilla hybrid, are both hardy in USDA zones 10 through 11, notes Missouri Botanical Garden. Mandevillas are prolific bloomers, but if your vine isn’t blooming, it may not be receiving the proper care or growing conditions.

Mandevillas require full sun for optimum mandevilla bloom time. The more sunlight your plant receives, the more flowers it will produce. While Missouri Botanical Garden notes that the plants enjoy afternoon shade in hot climates, if placed in shaded conditions, mandevillas will produce little or no flowers. If you have your mandevilla in a location that is partially shaded, move it to a spot where it will receive six to eight hours of direct sunlight each day and blooming should increase.

While adequate sunlight is a primary factor in mandevilla bloom production, lack of water or nutrients will lower the plant’s energy stores, which can reduce flowering. Plants that grow in hot, sunny spots like mandevillas can dry out rapidly. Check the soil daily during hot periods. Make sure it is consistently moist and don’t allow it to dry out.

In addition to watering, feed your plant every two to three weeks during the growing season with a water-soluble fertilizer that is high in phosphorous, such as 15-30-15. Mix at a rate of 1 tablespoon of fertilizer per 1 gallon of water. Fertilizer mixing rates may vary, so read and follow the label for specific application rates.

Mandevillas can handle a range of soil types as long as the growing medium is well-drained. If it is stuck in heavy, soggy soils, your plant may not flower as well as it should, because it is stressed. Ideally, mandevillas should be planted in a mixture of equal parts potting soil, peat moss and builder’s sand.

Mandevilla roots also like room in the soil, so if you’re growing it in a pot, make sure it has of space for the roots to spread within the soil and the pot has adequate drainage holes. Repot the plant in a larger container if necessary to give the mandevillas room to grow and bloom.

Mandevilla plants are summer bloomers that don’t bloom during the winter months because of the shorter days. This is normal. If you’ve brought your plant indoors for the winter, it won’t bloom unless it is placed in a sunroom or given supplemental lighting. However, even with additional lighting, the mandevilla may still go dormant until spring.

Don’t fertilize mandevillas that have gone dormant and water only when the soil is dry to the touch. Pests and disease don't typically affect these plants, but watch out for whiteflies and spider mites on overwintering mandevillas. In the spring, resume a regular water and fertilization program and the plant should begin blooming again.

Moreover, there can be several reasons why the Mandevilla plant is not blooming under your care. In this article, we’ll be discussing almost everything there is to know about the Mandevilla plant, why the plant is not flowering, and how you can get it to bloom.

Why Is My Mandevilla Not Blooming?

Your Mandevilla plant is not blooming because it is most likely lacking the proper care conditions to grow optimally. As a tropical and subtropical plant, the Mandevilla vine has certain requirements that need to be met. 

Also, another reason could be that it’s not the right season for it to bloom. The Mandevilla flowering season can differ according to where the plant is grown. For instance, the Mandevilla plant can flower any time of the year when it is grown in a tropical or subtropical setting.

Yet, when planted in more temperate climates, the Mandevilla blooming season usually starts in the spring or early summer.

How To Make Mandevilla Bloom?

There are several factors that can help get Mandevilla to bloom. We will be discussing each one to help you understand how they can affect the flowering of the Mandevilla plant. 

You will also learn to understand how one factor can influence the other factors. From this, you can start to figure out where you may need to improve.

– Make Sure the Plant Receives Ample Sunlight

The Mandevilla plant is a tropical and subtropical bloomer, and while the plant can tolerate some shade or even partial shade, the flowers often come out when the plant experiences optimal sun exposure. The more sun the Mandevilla plant receives, the more flowers will come out from the vines.

As we mentioned in the previous section, when your Mandevilla plant is thriving yet not flowering, this phenomenon may be due to a lack of sunlight exposure. So, you can place the Mandevilla plant in a spot where the vine can receive at least six to eight hours of direct sunlight. Do this gradually so as not to shock the plant from sudden sunlight exposure.

Ideal locations are south-facing spots or east-facing areas. Also, the gentle sun exposure provides adequate light without possible leaf burns to the Mandevilla plant.

On the other hand, some gardeners have noticed that the Mandevilla plant even enjoys the harsh noon and afternoon sun, while some species can also flower in areas with bright indirect sunlight. In any case, allow the Mandevilla plant to bask in the light, and pretty soon, you will begin to see the buds forming into blooms.

– Check if the Mandevilla Is Hydrated

To make sure that your Mandevilla is hydrated, you can check the soil at the base of it. The soil should be moist to the touch and not overly wet. When the soil is constantly wet, the condition may cause root rot, and if the soil is too dry, the Mandevilla plant will begin to wilt from dehydration.

When planted in temperate regions, reduce the watering during cooler periods of the year. Water only when the topsoil is dry an inch from the top.

Keep in mind that the tropical and subtropical nature of the Mandevilla plant means that it can get dehydrated easily due to the hot weather. Placed in hot and sunny areas of the home or garden, the Mandevilla plant will require more watering to keep it from drying out. Also, the bigger the plant gets, the more frequent it needs to get water, so keep that in mind too.

– Ensure the Plant Is Adequately Fertilized

Aside from watering, the Mandevilla plant can also require fertilizing every two to three weeks during the plant’s growing season. Using a water-soluble high-phosphorus content fertilizer can help the plant bloom. Fertilizer mixing ratios vary according to manufacturers, so you will need to read the directions for specific application methods and frequencies. 

You can discontinue fertilizer application during the cool winter days and resumed during the spring and summer seasons. Doing so will avoid unwanted reactions from the Mandevilla plant.

– Make Sure the Mandevilla Has the Correct Soil

To ensure a hospitable soil condition, you should make sure your Mandevilla plant has well-draining soil, preferably a mix of potting soil, some peat moss, and some builder’s sand. Provide the root system of the plant with some growing area. When placed in a container, repot the Mandevilla plant once the roots come out of the drainage holes.

So, poor drainage can be another cause why your Mandevilla plant is not blooming. When the soil around the plant retains too much moisture, this can cause the plant to go into survival mode. When this happens, the Mandevilla plant will focus all of its energy on repairing and healing itself and will not focus on producing flowers.

– Keep the Correct Room Temperature for the Plant

The Mandevilla plant prefers warm temperatures over colder ones. When the temperatures drop below 65 F, the Mandevilla plant may stop producing flowers and go into forced temporary hibernation. When exposed to cold temperatures for prolonged periods, the Mandevilla plant may experience a sudden demise and die off.

When the Mandevilla plant is placed in a container, you may bring the plant indoors if you live in a region where cold seasons exist. You should also ensure that your indoor temperature is around 65 F or higher. Otherwise, if left outdoors in the cold, the Mandevilla plant will eventually perish.

– Prune Your Mandevilla Plant Timely

Pruning can encourage the Mandevilla plant to bloom. Best done during repotting or during the early part of spring, pruning triggers the vine to produce flowers. However, we should note that the more important factors, such as light, temperature, and water, are already present at the ideal levels.

FAQs

– What Is the Magnificent Mandevilla Plant?

The Mandevilla plant is a tropical and subtropical genus of flowering vines. Moreover, the plant was first described in 1840 and named after British diplomat and avid gardener, Henry Mandeville. The Mandevilla plant is sometimes commonly called the Rocktrumpet plant, owing to its flowers that are in the shape of trumpets.

– Where Is the Mandevilla Plant Native To?

The Mandevilla plant is native to Central America, South America, Southwestern United States, Mexico, and the West Indies. Many varieties of the Mandevilla plant originally came from the rich forests of Rio de Janeiro, Brazil.

– Does the Mandevilla Plant Produce Flowers?

Yes, it does! As a warmth-loving vine, the Mandevilla plant often produces fragrant flowers, although some varieties do not produce any scent at all. The Mandevilla flower also comes in an array of spectacular colors, with many hybrids formed over the passage of time.

– What Makes the Mandevilla Plant Popular?

The trailing characteristics of the Mandevilla plant make the vine a popular plant in many gardens. Placed on trellises, pergolas, or against walls and balconies, the Mandevilla plant provides lush foliage and tropical beauty to many homes and gardens.

– Is Mandevilla a Hardy Plant?

That depends on the species. While the Mandevilla plant can be considered a tropical plant, some species can be hardy in USDA zones 9 to 11. 

Conclusion

• The Mandevilla plant can be coaxed into flowering when exposed to more sunlight, approximately six to eight hours each day. Also, as a warmth-loving plant, the Mandevilla needs temperatures above 65 F to grow and produce flowers
• The lack of water can cause the Mandevilla plant to stop flowering, so ensure that the soil around the base of the plant is consistently moist, and not excessively dry or wet
• The Mandevilla plant can benefit from fertilizers that are high in phosphorus to encourage the plant to bloom
• The soil of the Mandevilla plant should have sufficient drainage yet hold enough moisture to keep the plant hydrated. Equal parts of potting soil, peat moss, and builder’s sand are ideal
• Pruning can encourage the Mandevilla plant to develop blooms in tandem with the right levels of sunlight exposure, temperature, and watering.

Now that you’ve learned the important factors in getting the Mandevilla to bloom, you’ll know what you need to encourage your plant to flower. With the right patience and care, your Mandevilla plant will reward you with more foliage and breathtaking blooms in no time!