What Causes Bougainvillea Yellow Leaves?

One sight you don’t want to see is Bougainvillea yellow leaves. They look terrible on your bonsai, and it gives the appearance that your small tree is dying. You’ll need to look into what the cause may be, and how you can prevent it from happening.

Fear not! We have a detailed guide to help you observe the probable reasons with a few solutions!

bougainvillea yellow leaves

What Causes Bougainvillea Leaves to Turn Yellow?

When you have Bougainvillea yellow leaves on your hands, it’s often a sign that your bonsai tree is under a lot of stress. In some cases, it may just be that it’s going into dormancy, but that’s only the case where you live in a cold climate during winter. It’s actually an evergreen tree under the right conditions.

There are plenty of other reasons you may see your Bougainvillea’s leaves turning yellow, such as insufficient light and nutrients and too much water. We’ll take a look at a few of these in this guide so you can see how to deal with them.

Top Reasons for Bougainvillea Yellow Leaves

In this section, we’ll break down the top reasons you may see your Bougainvillea bonsai suffer from yellow leaves. These aren’t cast in stone, and they may also cause other issues, such as losing leaves or no flowers growing.

Water Stress

When it comes to Bougainvillea yellow leaves, both under and overwatering can be culprits. Since it’s a tree that loves drought conditions, it’s usually a case of overwatering. You’ll want to leave the soil to dry for about a week before you add any more moisture to it.

However, wilting is a sign that there isn’t enough water for it to survive. It loves rainfall conditions, so you may need to simulate it at home. Test the soil with your finger to see if it’s too dry, in which case you should drown it in water for about 30 mins.

Insufficient Sunlight

When plants undergo photosynthesis, the chlorophyll helps to absorb energy from sunlight so that the cells can use it. If there’s isn’t enough energy, it won’t produce new leaves, roots, flowers, and stems. One trait of chlorophyll is that it can’t absorb the green color of light, which is what gives it such a stunning appearance.

When you end up with Bougainvillea yellow leaves, it could be that there’s not enough direct sunlight for this process to occur. It needs at least six hours daily, mostly during the morning before the day begins. If it can’t create enough energy for the tasks ahead, the leaf will turn yellow.

Transplanting

There are three aspects to consider with transplanting. The first is preparing for the winter, where you bring it inside to protect it from the cold. Secondly, it’s taking your Bougainvillea outside for spring when the weather becomes warmer. Finally, it deals with buying a new bonsai and bringing it to your home.

All three of these can cause the leaves on your Bougainvillea bonsai to turn yellow. For the first two, we recommend a gradual change from inside to outside and vice versa. Let your tree become used to the new environment before you make the change permanent. For buying the bonsai, you just need to give it a few weeks to get used to your home.

Pests

Another top cause for Bougainvillea yellow leaves is a pest, such as a spider mite. They cling to the leaves and feast on the stems, leaving tiny web trails all over your bonsai. If you look at the leaves closely, you may even see small dots moving around.

The best solution is to remove infected leaves and spray the rest with an insecticide. The sooner you treat this, the better, as they are known to spread quite quickly. You can also try neem oil.

Cold

For the most part, Bougainvillea trees are evergreen, so you should expect the leaves to be green all year. However, they only do well in zones 9 to 11, and anything outside these areas may be too cold during winter.

You have two choices in this scenario. You can either let it become deciduous and go into dormancy, or you can bring it indoors and simulate the same, warm environment with bright sunlight. Even under the best conditions, you may need to succumb to the idea that the bonsai will go into dormancy anyway, which will cause the leaves to go yellow and drop.

Insufficient Nutrients

One of the macronutrients needed to boost foliage growth is nitrogen. However, there are two micronutrients that help to keep the leaves green. These are magnesium and iron, and specific Bougainvillea fertilizers are available with boosted amounts of these items.

It doesn’t help to add the nutrients if the bonsai struggles to absorb them. To aid with this issue, you can add Epsom salts to increase the levels. If you see the leaves are twisting while turning yellow, you’ll need to apply some chelated zinc instead.

Alkaline Soil

One more factor that plays a role in the absorption of nutrients is the pH level. If the soil is too alkaline, the roots will struggle to take in any food you provide. That means the magnesium, nitrogen, and iron will have a difficult time getting to the leaves, which is why they might turn yellow.

You’ll need to test the soil and get the pH to about 5.5, or at least under 6.0. In a few weeks, you’ll see a vast improvement in the leaves and stem, with new growths appearing.

bougainvillea yellow leaves

Can Yellow Leaves Turn Green Again?

Whether or not you can change Bougainvillea yellow leaves back to green depends on how far it’s gone. If it’s all the way yellow, there’s no way of transforming it back, and then the leave is lost. Usually, when you touch it, it will drop immediately due to its fragile state.

If the yellowing of the leaves has only started, there’s still a chance that you can save it. It might not go completely back to green, but it won’t lose any more color either. It all depends on how quickly you can diagnose the issue and solve the problem.

What Should I Do with the Yellow Leaves on My Bougainvillea?

The best thing you can do with Bougainvillea yellow leaves is to remove them if they’re too far gone. You’ll see them drop after a while anyway, but they are absorbing a small number of nutrients that are going to waste. That energy is best spent elsewhere, like on new shoots and roots.

The next step is identifying what went wrong and the cause of the yellow leaves on your Bougainvillea bonsai. With the guide we provided above, you should be able to readily identify the issue and resolve it going forward. Make sure you remove any more yellow leaves on the way to rehabilitation.

Tips for Preventing Bougainvillea Yellow Leaves

So now that you have the main causes of Bougainvillea yellow leaves, it’s time to see how you can prevent it from happening again. We have a few tips here below as a summary of some of the things we mentioned while adding a few more tricks you can try:

  • Don’t overwater your bonsai. Make sure you drown it once a week and let the soil dry out completely before you supply any more liquid. Once you feel the soil with your finger and there’s no moisture, you can bathe it again.
  • Make sure there’s enough magnesium and iron to go with the nitrogen. They help the chlorophyll in maintaining the energy needed for the cells, keeping your leaves healthy and strong.
  • Add some Epsom salts to increase the uptake of magnesium and iron into the bonsai tree.
  • Keep the Bougainvillea warm in the winter months if you don’t want it to go into dormancy.
  • Whether summer or winter, make sure there are at least six hours of sunlight during the day to create enough energy. However, don’t let it take in more than 12 hours of direct light.
  • Keep watching the tree for any signs of pests and diseases.


bougainvillea yellow leaves

Final Thoughts

As you can see, there are plenty of reasons for your Bougainvillea yellow leaves. Not all of them are fatal, but you’ll need to react quickly to prevent more leaves from suffering the same issue. We hope this article has guided you in some way from avoiding it altogether, and you managed to save your bonsai tree.

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