Chop sticking is a very important technique in the repotting process and its probably something most people skip and don't realise that its hurting the cultivation of their trees, So why is chop sticking important? lets take a look
When it comes to re potting bonsai there are many techniques involved in a single sitting and scope of work, this makes it probably the most risky work we do and something we should all understand as i believe most trees live and die by their last re potting. When we re pot this is supposed to be almost like a refresh for the bonsai tree, this is obvious by the sudden vigour a tree will gain after the repotting work, But if done incorrectly this can be quit the opposite effect. So lets have a look at the technique we call chop sticking.
If i were to put it in a simple sentence i would say chop sticking bonsai is done to remove air pockets from soil to prevent the soil system from having areas that the roots wont grow into which will limit the root system you can have in an already small amount of space. too much oxygen = dead root tips.
The way we go about chop sticking is after we get our tree secured down onto our drainage layer of soil in the bonsai pot we will then proceed to backfill around the root system. If we were to just back fill alone this would leave us with a whole bunch of air pockets in around the root system. Once we have filled the pot up with soil we then take a chop stick ( bamboo or wooden ) and start working the soil, we do this by driving the chopstick to the bottom of the pot and working the stick in and out while slowly bringing the chop stick closer to the surface, essentially what this does it breaks apart pockets and allows soil to fall into the voids, as you do this you will notice the soil level sinking in the bonsai pot which shows you just how much empty space was in and around your trees root system. I like to start from the middle and work my way out, This step is repeated the whole way around the tree until i see the soil stop sinking and i can begin to feel the soil structure become more or less solid compared to how loose it will be to begin with when it is full of air pockets.
Here is a video from my youtube where i use this method
Now when wouldn't you chopstick? i wouldn't recommend it with organic soil in a growing pot, by doing this you will be compacting the soil and making it harder for an already moisture heavy mix to take on oxygen.
Why Wooden or Bamboo ChopSticks? When it comes to working on something like your root system if something has to give you want it to be the chop stick and not a root. The wooden and bamboo chop sticks are a lot less aggressive on the root system. Bamboo chop sticks last a lot longer and are also useful for penetrating into a solid root ball to use as a tie down point but are more expensive. Wooden chop sticks can be bought in packs of hundreds for a few dollars so even if you break 2 or 3 per repotting it isn't a big expense. they are also useful for creating anchor points for trees but you need to be more carful as they aren't as strong as the bamboo, i usually use 2 chopsticks rather then 1 in this case.
I hope this is something that helps with your next repotting season and sets you up for further success in the future for your trees.
Until Next Time, Enjoy Your Bonsai Journey.