Why do Bougainvillea Lose Their Leaves? | 5 Ways to Prevent Leaf Drop

Bougainvillea plants love mild and tropical climates so if the temperature drops too low in winter they can lose their leaves. Any stress to the plant can also cause them to lose their leaves including strong winds, root disturbance, overwatering, underwatering and frosts.

Bougainvillea are hardy plants but cold weather will cause them to drop their leaves. If the plant is well watered they will grow back new leaves and flowers in spring. Feed them with a gentle, slow release fertilizer when the weather warms like pelleted chicken manure.

This article will explore why bougainvillea lose their leaves and how you can prevent this.

7 Reasons why bougainvillea lose their leaves

Here are the top causes of bougainvillea losing their leaves. Check out each one to see if this is the cause for your pant at home.

1. Cold weather

Cold weather is the top cause of bougainvillea losing their leaves. Temperatures below 40 degrees Fahrenheit (10 degrees Celsius) will stress these tropical plants and cause leaf drop. They can lose some or all of their leaves when exposed to cold temperatures.

Bougainvillea will be evergreen in tropical or sub-tropical climates. I live in a sub-tropical climates and most plants will keep their leaves all year round. When we get very cold winters, plants will lose around half of their leaf coverage.

Do not worry if your bougainvillea looses its leaves in winter. Mulch the plant well, water it every 2-3 weeks deeply and it will grow back strong in spring. Trim back any damaged stems and you will see new growth fast. I like to feed my bougainvillea with a handful of pelleted chicken manure when the weather warms up to boost leaf growth.

Avoid adding too much nitrogen however as this can reduce the flower growth on these plants.

2. Frosts

Frosts can damage bougainvillea leaves causing them to drop almost instantly. You can lose a the whole coverage of leaves in one night if frosts are heavy.

Bougainvillea plants that are growing in pots can be protected from frosts over winter. Pull the pot into an area that has overhead trees or branches or place them under a verandah.

You can then move them back out into a full sun position to encourage new leaves in the spring.

3. Wind

Strong winds can cause bougainvillea to lose their leaves. These plants are not keen on extreme weather conditions so hot or cold winds can stress the plant. Both can result in leaf drop if the plant is not protected.

If you experience lots of winds over the winter or summer it is best to leave extra growth on the stems to help to protect it. Outer leaves and stems will protect the inner ones so the whole plant does not lose all of its leaves.

Growing bougainvillea up a garden screen that protects them from the majority of the wind is ideal. These plants will grow up the screen and make a great feature in your garden.

4. Not enough light

Bougainvillea that are not getting enough sunlight will have limited leaf growth and can drop their leaves over time. Bougainvillea love full sun so excess shade will limit their leaf growth.

Move potted bougainvillea to a full sun position in the spring and summer. This will give you loads of new leaves which will form the colorful leaf ends that we all expect.  

5. Transplant shock

Bougainvillea that have been moved or repotted can experience transplant shock if their roots have ben damaged. Bougainvillea roots are sensitive to any damage or movement. Damaged roots can allow water, fungus and bacteria to enter the plant.

The damaged roots will not be able to absorb nutrients and water as the plant needs. This can slow the plants growth and lead to leaf drop.

When transplanting bougainvillea it is best to limit the amount of root disturbance. This means cutting off plastic pots if you can to get them out.

Avoid using rakes or digging on top of the root zone of bougainvillea growing in the ground. Even disturbing the roots near the surface of the soil can affect the plants growth. Cover the root zone with 2-3 inches of bark mulch to protect them from damage.

6. Overwatering

Overwatering bougainvillea can lead to root rot which will cause the leaves to curl and drop. While these plants like regular water over summer, allow them to dry out between watering. In winter you can reduce your watering even further.

Try to mirror the tropical climate and give them lots of regular water in summer when the weather is humid and allow them to dry slightly when it is cold and their growth has slowed.

7. Drying out

While overwatering can cause damage to bougainvillea, underwatering can also lead to leaf drop. Underwatered bougainvillea will develop yellow and then brown leaves. These dry and dead leaves will drop off leaving the branches bare.

The branches can regrow new leaves if the problem is caught early. Using your house, deep water the root zone and completely soak the area. For potted plants you can water on a mix of seaweed solution to help the roots to recover.

Top ways to prevent leaf drop in bougainvillea

Here are my top ways to prevent leaf drop in bougainvillea at home. These easy tips will help to keep your plant covered with leaves and growing well.

  1. Protect them from cold weather
  2. Do not disturb the roots
  3. Give them regular, but not too much water
  4. Move them in to a sunny position in spring
  5. Trim back damaged stems after summer

Why do Bougainvillea Lose Their Leaves? | Summary

Bougainvillea will lose their leaves if they are stressed. This could be due to cold weather, winds, drying out or due to transplant shock. Protecting the plants from extreme cold, watering them regularly and taking care of their roots is the best way to prevent leaf drop.

Happy growing.