One of the biggest problems with using hot pepper plants for bonsai is the leaf size, but it’s not a unique problem in the bonsai world.
There’s always a risk of killing your plant when you do anything to it. Most of the tips for getting small leaves involve things that have quite a high risk to the health of your plant. I wouldn’t advise doing all of them to your plant in the same year as it could stress your plant too much.
Start With the Right Kind of Plant
There are certain pepper plants that are more suited to bonsai – particularly compact and ornamental varieties. If you go for one of those it’ll make this whole process a lot easier but, even if you decide to go for something a bit unsuitable, you should see a reduction in leaf size by trying some of the other tips.
Defoliation is where you cut off all of the leaves of your plant. It can be quite stressful for your plant and equally stressful for you as you wait to see if you’ve just killed your bonchi.
An easier, less fear inducing type of defoliation is semi defoliation. Instead of taking off all the leaves you only take off most of them. Removing most of the leaves when the plant has just sent out it’s spring growth means that most of the energy that was stored in the roots has been used up making the first batch of leaves. Because there’s less energy for the second set of leaves they’ll grow in much smaller.
I’ll put together a post on defoliation soon as it’s a little trickier than just ripping off the leaves. Basically, you need to leave a piece of the leafs stem attached to the plant so don’t try and cut it level with the trunk or even worse, pull it off. If you do you could damage the node where the second leaf would grow out of. Make the cut at the bottom of the leaf itself instead.
There’s a few different ways to encourage your plants to branch. Topping, FIMing and defoliation are the most popular.
The more branches your bonchi has, the more leaves it’ll need to produce to support them. Because it needs to grow more leaves off the same sized root system, the leaves will grow through smaller.
It can be intimidating to root prune a healthy looking tree but doing it to a sad looking overwintered pepper plant is even worse. It will help you get those lovely miniature looking leaves though.
When your plant goes dormant it stores energy in the roots, once the right conditions are met for it to wake up again it uses that energy to grow new leaves. By root pruning during the dormant phase, you’re restricting the amount of energy the roots have to create that new growth resulting in smaller leaves.
Usually when you overwinter peppers you cut off the majority of the growth. If you’re root pruning to reduce the leaf size you’ll want to leave the plant as big as you can so the energy stored in the pruned roots needs to feed a larger plant.
If root pruning and defoliation seem too extreme then you could top prune instead. It’s pretty similar to semi defoliation but a bit less intense and more aesthetically pleasing. Basically, you prune it to make it look nice, to ensure light is getting where it needs to go and to keep the plant generally healthy. Check your plants as often as possible and remove any growth that is getting too large. Your plant should respond (assuming you didn’t damage the node) by growing a new leaf from the same node but it’ll be a third of the size. Doing the same thing a second time will give you a leaf a third of the size of the previous leaf. After that you probably won’t see additional shrinkage.
It’s top of my list to try this year to see whether it actually works as it’s another technique ripped straight from the world of bonsai.
I don’t advise doing top pruning on a plant growing new leaves after a root pruning. If you root pruned your plant during the dormant phase then let the plant grow for a while and lightly prune it when its filled in and is looking healthy.
To grow healthy plants you need to make sure they’re getting the right nutrients. If your bonsai is in a small pot it’s even more important as there’s less soil for the plant to get nutrients from.
However, there is a certain nutrient that plays a big role in leaf growth. Nitrogen.
Limiting the plants nitrogen slightly will help keep the leaves small but it can have other nasty side effects, the most drastic being chlorosis which will kill your plant. Yellowing leaves is a sign of nitrogen deficiency so if you’re going to mess with your nutrients then keep a close eye on the leaves. You’ll probably have to experiment a bit to figure out how much to feed your plant and it what ratios to keep it healthy and get that smaller leaf growth.
Because bonchis are kept in small pots they’ll become root bound fairly quickly. The reduced root size will help keep the leaves small as the root system isn’t large enough to produce and support larger leaves.
You don’t want to go so small that the plants overall health is negatively affected but letting your plants get a little root bound before repotting/root trimming will help it produce smaller leaves.
I’ll be doing some experiments with bonchis this year and a lot of them will be looking at how to affect the leaf sizes so if any of you have anything you think might work let me know! I love putting on my lab coat and experimenting on my poor little bonchi.
I’m curious to see if there’s a way to make smaller chillis as well as I’m sure I’ve seen pictures of bonsai fruit trees with miniature fruit but I’m not sure if that’s photoshop or not.