late potting or repotting your bonsai

Sneak Peek

Who doesn’t dread the idea of late potting or repotting a bonsai? It’s all supposed to get done on time. But ….

Late Potting or Repotting Your Bonsai

There’s potting time for bonsai, which is usually repotting time. It’s supposed to happen at the time which is ideal for whatever species you’re growing. Now, everyone out there who always does this at the ideal time, raise your hands ….

I committed my first potting/repotting sin over 30 years ago, and am still going strong today! No, it’s not something I do for fun, it’s just a necessity sometimes. The good news is, I’ve learned a few tricks that pretty much ensure my trees will survive my transgressions. I’ll share them with you today.

Let’s start with this small Swamp maple bonsai I first potted back in 2019. I had grown it from seed, and after a few years it had a nice trunk with good movement and taper, and I knew I could complete the development of the tree in a bonsai pot. That was two years ago, of course, and as you might suspect from the size of the pot it’s in, there isn’t any more room for roots. You can see this lack of space reflected in the foliar growth – the leaves have some deformation in them. So the tree is struggling to continue on.

The obvious answer is to repot the tree. The obvious problem is it’s already fully in leaf. What to do?

First let’s take off the ugly foliage. It’s going to have to come off anyway, as it’s much too large and the needs of ramification mean defoliation step by step as new growth emerges.


Out of the pot it comes. I think the problems with growth we already noticed directly reflect the overcrowded root system.

Now, you may be wondering if it’s okay to root-prune at this time. I can say I’ve done it, but when I do it’s usually a light root-pruning. Many species can take a lot of abuse, but there’s no point in pushing things if you don’t have to.

In this case of this tree, it needs large pot so that gives me the opportunity to slip-pot and not cut any root at all. And that’s ideal in cases like this one.

I just in some round pots from Byron Myrick, and I think this one suits the tree very nicely. Obviously it’s roomier, and that will help me achieve my goal of increasing the trunk size of this tree (yes, I know that’s a slow process but I accepted a smaller specimen when I first potted it; if I had wanted a thicker-trunked specimen I’d have put it in the ground).

It’s fun to push the envelope from time to time, so how about potting up this Ginkgo today? Well, the tree is fully in leaf so that’s going to be risky. The bonsai pot this tree goes in is going to be a lot smaller than the nursery pot you see – that means a lot of roots will end up on the ground. So my risk goes up quite a bit. But there are a couple of things you can do when faced with this situation.

First I need to pick out a pot. There’s this Kintsugi I made over the winter. The tree will certainly go in it fine, but I’m interested in a more permanent home.

Here’s another Byron pot, and I’ve got to say I think this match was made in heaven. Let’s find out.

Yes, I think this really nails the composition. With this Ginkgo, I’m not looking for a much heftier tree; I’d like it to stay the height it is now, and fill out over time. So this pot should suffice for a very long time.

Okay, so the tree’s potted now and it has lost about 75% of its root system. That’s risky, to be sure. So how do we mitigate the risk? One thing I’ve already done is to remove one of the leaders on the tree. That’s not a huge amount of the top-growth, but it is some and it helps to balance the root loss. Whenever possible, I recommend keeping the balance between root removal and foliar removal as equal as you can. That way the stress on the tree will be lessened.

I have one more trick to ensuring (as best I can) that this tree survives the late potting.

Always keep a supply of produce bags handy. They’re great for maintaining the humidity surrounding the foliage of your tree, which prevents transpiration losses while the root system regenerates. I expect to have this bag on the tree for two to four weeks.

You may have noticed the twine I used to lash the bag to the pot. In your garden or yard, anything that an act as a sail will do so – in fact, if you want to kick up a breeze try bagging some cuttings. It works for me every time!

Let me know what you think of today’s work. Do you pot or repot out of season?