Wild Mandevilla are vines that have dark green leaves and showy blossoms. Some newer hybrids are mounding but still have impressive flowers. Mandevilla is a popular plant to grow. You may be wondering, “Does Mandevilla need full sun?”
Picking the best spot to grow a new plant can be confusing. Read this guide to find out where to place your Mandevilla for the best results.
Does Mandevilla Need Full Sun?
Mandevilla grows best with at least six hours of sun a day. While the plant will grow in partial shade, the blossoms will be smaller, and the plant won’t have as many of them. The Mandevilla will also be leggy and won’t have as many leaves.
How Much Sun Does a Mandevilla Need?
Mandevilla needs at least six hours of direct sun a day outdoors. Indoors, because the bright, indirect sun is weaker than the direct sun, a Mandevilla will do better with sunlight all day long.
Enough sun will result in:
- Leaves will be a more vibrant and darker green.
- The blossoms will be larger and more frequent on the vines or branches.
- The vines or branches will be bushier and thicker with the right amount of sun.
Can Mandevilla Get Too Much Sun?
Sunlight isn’t the problem; heat is. If you live in a hot climate, the best place for your Mandevilla while it is outside is where it gets morning sun and afternoon shade. The afternoon shade helps keep the Mandevilla from getting too hot and dry.
Indoors, as long as the temperature and humidity are adequate, a Mandevilla can’t get too much bright, indirect sun. Direct sunlight will burn the leaves.
Can I Plant Mandevilla in Shade or Indirect Sun?
Mandevilla will not grow in full shade. The plant will grow in partial shade (2-6 hours of sunlight), but it will not do as well. Indoors, Mandevilla needs indirect sunlight. Again, the plant will grow in partial shade but will not do as well. Even indoors, Mandevilla will not grow in full shade.
What Happens If Mandevilla Does Not Get Enough Sun?
If the Mandevilla does not get enough sun, you will see these problems:
- Smaller blossoms
- Fewer blossoms
- Smaller leaves
- Muted colors in the leaves
- Fewer leaves
- Leggy vines or branches
Where Is the Best Place to Plant a Mandevilla?
The best place to plant a Mandevilla varies a little according to the hemisphere you live in.
In the Northern Hemisphere
- In the ground, place the Mandevilla facing south. If you live in a hot climate, do not place the plant against a surface that radiates heat, such as a brick wall, or it will get too hot. Mandevilla in hot climates do better someplace where they get morning sun but afternoon sun. This location is often an easterly or westerly facing area.
- In an outside pot, the same locations will provide the sunlight your Mandevilla needs. Mandevilla in pots is more likely to need afternoon shade because the heat will dry the soil excessively.
- Indoors, summer locations include southern, easterly, and westerly facing windows. Remember, direct sunlight will burn the leaves indoors.
In the Southern Hemisphere
Substitute northern locations for southernly ones.
Interactions Between Sunlight, Water, Humidity, Temperature, and Fertilizer
Sunlight doesn’t affect plants in a vacuum. The amount of water, humidity, and fertilizer a Mandevilla needs goes up or down as the amount of sunlight and the temperature go up or down.
Temperature is closely linked to sunlight. As the sunlight increases, so does the temperature.
While outdoor Mandevilla needs a temperature of at least 60 degrees at night and at least 70 degrees during the day, very hot temperatures are hard on the plants. High heat increases water and humidity needs and decreases fertilizer needs.
In hot climates, afternoon shade helps keep the temperature of the soil and plants down. If the temperature is too high, the plant cannot draw up enough water to regulate its temperature and will dehydrate and die.
Plants in pots dry out faster and get hotter than Mandevilla growing in the ground.
Established Mandevilla growing in the ground can tolerate some drought.
Plants in pots cannot because the smaller amount of soil does not hold as much moisture. Mandevilla in both situations does better if they are kept evenly moist. Using a moisture meter helps eliminate guesswork about the moisture in the soil.
Water as often as necessary to keep the soil moist but not wet. The number of times you will need to water will be more when it is hot than when it is cooler.
Reduce watering in the winter but do not let the soil dry out between waterings.
If you have difficulty with fungus gnats indoors, let the top of the soil just dry out between waterings to keep the gnats from growing there.
Mandevilla is a tropical and subtropical plant. Because of this, Mandevilla needs high humidity to do well. Hot climates increase the humidity requirements of the plants.
Mist the leaves in the morning if your climate is dry. Pots can be set on pebble trays. Take a tray larger than the saucer for the Mandevilla and fill it with pebbles. Fill the tray with water, so just the tops of the pebbles are dry.
Set the Mandevilla, saucer and all, on the top of the pebbles. As the water evaporates from the tray, it creates a humid microclimate around the Mandevilla.
Remember to refill the pebble tray with water regularly.
Mandevilla is a heavy feeder. In the early spring, place a fertilizer that has at least half slow-release granules around in-ground plants. Work the fertilizer in the top two or three inches of soil, being careful not to damage the roots of the Mandevilla.
For Mandevilla in pots, fertilize with a water-soluble fertilizer for indoor plants mixed at half strength every two weeks. Choose a fertilizer high in phosphorus. Do not fertilize during the fall and winter.
In extreme heat, especially when the humidity and ground moisture is low, Mandevilla needs less fertilizer. Make sure you water any fertilizer in and keep the ground moist to avoid burning your plants. Potted plants are especially vulnerable to fertilizer burn in these situations.
Will Mandevilla Survive Winter Outside?
The temperature during the winter where you are determines whether Mandevilla will survive the winter outside. Mandevilla grows best when the night temperature is at least 60 and the day temperature is at least 70 degrees.
When the temperature gets below 40-45 degrees, the foliage starts to die back. If the temperature gets below 30-35 degrees, the roots die. If your winters get below 35, your Mandevilla is unlikely to survive the winter.
Growing your Mandevilla in a pot allows you to bring your plant indoors during the fall and winter. You can then set the pot outdoors when the temperature warms up enough for the Mandevilla to survive.
In summary, Mandevilla needs at least six hours of direct sunlight outdoors to grow best. Indoors, Mandevilla needs at least six hours of indirect sunlight. More indirect sunlight will help compensate for the difference in light levels indoors.
The Mandevilla will grow in partial shade, but it will be a shadow of itself without full sun. Moisture, humidity, and fertilization needs will change depending on sunlight and temperature, so be sure to compensate for higher temperatures when caring for your plant.