Why Does My Bonsai Tree Have Sticky Leaves?

After giving your bonsai tree all of the care in the world, it can be quite worrying noticing that the leaves are starting to get really sticky. Either you’ve spilled something on your tree or your bonsai has got infected. In this article I breakdown exactly why your bonsai tree has sticky leaves and exactly what you can do to treat it – luckily it’s not too dangerous.

Sticky foliage on a bonsai tree can only be caused by either scale pests of aphids. Both of these insects ‘honeydew’ onto the leaves, which is why the leaves feel sticky. These pests are not dangerous to your bonsai and can easily be treated quickly using very simple methods.

So Why Does Your Bonsai Tree Have Sticky Leaves?

Your bonsai tree has sticky leaves because it has been infested by either scale pests or aphids. These insects secrete a substance called honeydew, which feels sticky to the touch. Usually honeydew will be coating a lot of the foliage on your bonsai, giving it the feel of being sticky.

A lot of owners genuinely have no idea for months when their bonsai has scale insects of aphids as typically they aren’t the easiest to spot and can go unnoticed for a while.

You might be wondering how your bonsai tree actually got pests, as you have such a good maintenance routine. The simple answer to this is the pests have either come from another infected tree, or they have flown onto your bonsai tree from outdoors. No matter how good your watering and pruning routines are, they cannot really stop the infestation of pests but it could prove more damaging to a weaker bonsai tree, than a stronger one.

The risk of your bonsai tree getting infested with aphids or scale pests is greatly increased when living outdoors but this is the only option for a lot of species of bonsai. More importantly, the benefits of growing a bonsai tree outdoors are huge in terms of the air, light intensity and growing conditions.

Does My Bonsai Have Aphids Or Scales?

If your bonsai tree has sticky leaves, I wouldn’t worry about trying to diagnose whether it is infested with either scale pests or aphids. This is because the treatment is the same regardless of which pest you are dealing with, so wasting time trying to figure out which has infested your tree is relatively pointless.

For reference…

Scales are small wingless insects that tend to live on the branches of a bonsai tree, rarely on just the foliage.
Aphids tend to live on the underside of leaves and come in many different colors, brown, green, red or grey.

If you’re still unsure to whether your tree is infested or not, check if there are any ants around the pot, humidity tray, soil or the branches. Typically ants love to feed on honeydew so when your tree is very infested it’s rare to not have ants nearby.

Aphids use their mouths to latch onto your bonsai tree, purely to feed on the sap it contains. A by-product of this is the honeydew they secrete, which causes the sticky leaves. Although relatively harmless in small quantities, these insects can come in numbers and your tree could be infected with up to 150 of these ‘plant lice’ at any time.

How Can You Remove Aphids Or Scale Pests From Your Bonsai?

As scary as it can be having something infesting your bonsai tree, scale and aphids are not actually all that dangerous to the overall health of a bonsai tree, providing the normal care requirements for the tree are being met. Although there isn’t an immediate danger, treating anything you see on your bonsai tree is the best way to keep the tree healthy over the long term, instead of letting anything mount up.

The most common ways to get rid of pests on your bonsai tree are:

Soapy water
Vinegar solution sprayed
Pesticide treatments applied

All of these 3 methods for removing the pests causing sticky leaves on your bonsai tree are very effective. For most small infestations the soapy water method will work but with a larger pest problem you may need to use the pesticide method.

So, this is how you can remove the aphids or scale pests using soapy water…

1. Move the bonsai tree outdoors (unless it’s an outdoor tree, in which case you’re all good)

2. Using a hose on low pressure, start washing the tree with water. Ensure you cover all of the branches, small branches and even the underside of the leaves, be very thorough.

3. Create a mix of water and 2-3 drops of soap.

4. Apply that mix to the tree gently, ensuring you thoroughly clean it to get rid of the insects.

5. Using a clean wet cloth, wipe the bonsai tree all over to ensure the soapy solution is all removed.

6. Return the tree to it’s usual growing conditions and keep a close check on any insects, should they come back.

If this simple method doesn’t remove the pests from your bonsai tree or they come back in force, the final option would be to bring in vinegar. Create a solution of 2 parts water, 1 part vinegar and fill a misting spray bottle with it. If you treat your bonsai tree with this, the insects are going to die off extremely fast.

The vinegar method is very effective but for most light pest infections the soapy water solution should suffice. Should this sticky foliage issue keep coming back, I would take your bonsai tree to a specialist at a local bonsai nursery. They can often recommend great products to use such as pesticides that will be fine to use on your species.

Pesticides are riskier to use as when used incorrectly to treat aphids, they can actually do just as much damage to your bonsai tree. Most are said to be relatively safe when used correctly and shouldn’t actually leave any toxins on your tree. Going down the pesticide route could take a while as usually multiple treatments are needed, however this greatly reduces the possibility of the pests coming back any time soon.

Conclusion

If your bonsai tree has sticky leaves, aphids and scale pests are usually the culprits. They aren’t dangerous and can be easily treated using a soapy water solution or by spraying a solution of two parts water, one part vinegar over the infested areas. Pesticides can be used in small doses to treat these pests too but I would advise contacting your local bonsai nursery first to ensure the product you use is safe for your tree species.

Treating your bonsai tree for aphids and pests should be done as soon as you notice the insects or the honeydew secreted. Keeping up a proper care routine for your bonsai after treating is the best way to nurse it back to full health and ensure the tree hasn’t taken too much of a toll.