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Autumn Bonsai Work

Updated: Jan 7, 2023

Autumn can be a confusing time in Bonsai for those of us just starting out, We see the usual crowd wondering why there tree is turning different colours and losing all of its leaves. At this point panic usually sets in. For those of us that understand the autumn cycle we need to make sure we prep the trees for the next 2 seasons. Its kind of like painting a car or the walls in your house, you always get better results when the proper prep work is done. Bonsai is no different.

Lets quickly start out for those of you just getting into the hobby and explain whats happening to some of your trees. In bonsai deciduous trees are very popular and the most common trees in this category are maples, elms, hornbeams, hawthorns and cypress just to name a few. These trees will begin to change colour and eventually drop all their leaves during winter. As we move into the colder weather and the days become shorter the tree begins to pull its resources from the leaves causing them to change colour and eventually dry up and drop off the tree. The tree stores all its resources to get it through the winter period and to push growth again in the spring season. It is important that moving into spring we dont prune any of our deciduous trees as this can cause the tree to push another round of growth which may not have the time to harden off, reset buds and regain the vigor it had.

Now what about general Autumn work? what should we be achieving in this period?

  1. Big Bends- If you have trees that need some major bends done now is the time, The tree is more likely to respond positively to harsh bends during its phase of vascular growth during the autumn season and there is a period of weather that is not freezing but it is also not overly hot allowing the tree to recover well. You can also do wedge cuts on your pines during this time if you have a thick trunk or branch that needs a little extra help moving.

  2. Interior Cleaning- Approaching the end of autumn we need to clean up any extra interior growth that may not get enough sunlight but more importantly we need to clean out the interior to allow air flow through the tree in the winter period. This is important to stop any moisture from sitting in your branches creating a cold dark damp environment inviting fungal issues and rot.

  3. fertilisation- This one is important, right now you need to be feeding your trees up to help with the spring push on the other side of winter. Any fertiliser you apply now you will see the results of in spring time. If you don't feed now you may see weak spring growth on your tree, people usually feed at the start of spring thinking this will help the tree grow but when the tree first push's new growth in spring it is using the resources we give it now.

  4. Green House preparation- If you live in an environment that requires protection for your trees over the winter time then now is a good opportunity to get in the green house and make sure there is enough room for all your trees and the green house is still sealed to prevent frost from entering. You dont want to get to the first frost and realise not all your trees have room on a bench or there is snow getting through.

  5. Purchase of Repotting Supplies- Starting to slowly get together the supplies you need for repotting at the end of winter or early spring depending what trees you have will make life easier when the time comes around. Repotting season can sneak up on us and most of the time we have a limited window to get the work done and you dont want to be chasing up supplies. Things like pots, potting mesh, substrate, sickles, sieves, soil scoops, shop sticks and wire. Have a look at what trees need repotting now and begin to take note of what trees will need a pot and how much substrate you think you may need.

  6. Adjust Your Watering- As the trees begin to slow down so does their water uptake, you will notice during autumn your trees will stay wet longer due to both a limited amount of transpiration in your trees and also the temps outside are not hot meaning the water in the pot will sit longer. Autumn is a strange time of year for watering as some trees will continue drinking at a fast rate while others slow right down. last week i watered some of my junipers almost every day where as i watered 1 of my trident maples twice all week. Make sure you are actually monitoring your trees and their water needs rather then just watering every day.

As a quick side note also remember to listen to your trees and not your calendar, the tree can either begin dormancy early or late depending where you are but the seasons begin on a scheduled date every year. This doesn't mean the weather actually follows suit. i have found the last few years here in Australia our seasons where i live in particular seem to be about a month late.

Until Next Time Enjoy Your Bonsai Journey

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Mar 29, 2022

What's wrong with liquid fertiliser? Why organic, which only becomes available to plants after a few weeks only, not right away?


Mar 29, 2022

Hi Josh,

Would it be possible to elaborate in more details on "wedge cut" technique please? Here or in another post. I didn't hear before about it. Quickly searched internet and found hardly anything relevant.

I have a few 3-4 yo JBPs I have grown from seeds, with mostly straight trunks. I'm happy with their D of 20-25mm as I'm after very small bonsai, say 15-20cm tall so it would be good if I could add more movement by bending but too thick for wiring. I would appreciate a link to any info about how to do wedge cutting, please.



Apr 13, 2021

Any particular fertiliser you would go to for this time period? I have junipers, jbp, an elm and trident maple. all in development.


Apr 14, 2021
Replying to

If your trees are all in development just go for something with a neutral NPK.

Something in the higher end with nitrogen, you will hear some people say no nitrogen during autumn but that is for specific cases. I'm guessing you want your trees to grow as much as possible in spring so give them a good all round feed. if you can get something with micro nutrients as well then even better. Use organic fertiliser and not liquid.

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