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10 things to do to prep your Bonsai for the growing season - Repotting Procedure

The new growing season is upon us and time is running out to get everything we need. It can be a bewildering time with so much to decide but with this series we will look at all the necessary items we will need over this 10 part series.

Re-potting Procedure

One of the most exciting and stressful times in a bonsai growers season is when new life starts bursting through the cold and weary weather. New buds start to swell with the oncoming of Spring. This is our cue to get ready for the hard work ahead.

Why do we repot?

  1. To keep trees healthy and invigorate them

  2. Nutritional content of the mix decreases due to root growth

  3. Pot has become root bound and a tangled mess

  4. Root pruning encourages new growth of branches, roots and leaves

  5. Increase size of pot for better growth

  6. Proper positioning of a tree in its pot (change of front)

  7. Removal of weeds otherwise difficult to remove

  8. Changing of the pot for better composition

  9. Insufficient drainage

  10. Cleaning of the pot and removal of lime scale

Preparation before repotting

What do you need?

  • All the necessary tools, example: Scissors, Root rake, wire cutters, root cutters, jinning pliers, chopsticks and a saw

  • Sufficient growing mix

  • Chilean Moss that is already sieved fine and ready.

  • Clean pots for different options if your first option does not work

  • Clean working area that is sanitized as well as all tools and pots

  • Drainage mesh or gauze for covering of the holes

  • Different grades of wire for tying in trees into the pot and securing the drainage mesh to the pot

  • Spray bottle with water for misting of the roots during repotting

  • Create an area where the trees can be placed for 2 weeks after repotting. Best is a shade net or greenhouse structure to block strong winds and harsh sun rays.

  • Cloths to clean repotting area and tools between trees.

Lets get repotting...

Step 1: Get all your necessary items together and ready for repotting as above

Step 2: Select the tree you wish to repot and the pot choice. Secure the drainage mesh over the drainage holes using a butterfly design(View our YouTube video on preparing a bonsai pot for more detail). Insert wires for tying in the tree. 2mm is usually the best grade for most trees however 3mm or 3.5mm can be used for larger trees.

Step 3: Remove the tree from its current pot carefully. With care use either a root hook or chopstick to slowly tease the root ball open. Start from the sides of the root ball and move upwards and downwards loosening the soil as you go. Try not to break roots at this stage while doing this. An effective technique is to "stab" the root ball with the chopstick and work all the way around till it starts falling apart.

Keep on teasing out the root ball until enough of the roots are exposed for root pruning and selecting.

Step 4: Place the tree in a container with Bioroot and water. This step is one of the most important steps done during repotting. Bioroot has just the right amount of trace elements, plant hormones and seaweed extract. This is used to reduce the stress of the repotting and to feed the roots for quicker stabilizing and fine root growth in the new growing medium.

General rule of thumb is add a capful of Bioroot to 10 liters of water. Place the tree into the water mixture while preparing the pot with growing mix etc. We allow the trees to soak for about 10min before removal.

Step 5: Place the tree on a flat level surface and carefully tease out the roots. Remove any crossing roots leaving only the best possible ones to grow and develop the root structure. Directly under the base remove any roots growing from this area. In time the root system, will look like an upturned side plate, slightly hollow underneath with a radiating root system developing at a slight downward slope. Prune the root system depending on the species between half and 2/3thirds. Make sure to research and get professional advise on specie specific procedures.

Remember to mist the root system or place back in the Bioroot mixture to avoid drying out.

Once complete the root system should radiate beautifully from the base and taper from large roots to fine in a short space. This can take many years to accomplish depending on the species and development thereof.

Step 6: Prepare the pot for your tree by making sure it is on a level surface. Add a layer of growing mix into the pot and heap more of the mix where you want to place the tree. Either on the left third line or right third line. This depends on the movement of the tree either to the left or right. Generally speaking when the tree is leaning to the left, plant on the right third line of the pot, when leaning to the right, plant on the left third line.

Keep the tying in wires neat and ready to be use in the next step.

Step 7: Place the tree in the correct position in the pot to create a beautiful composition. Apply pressure and wiggle the tree down into the heaped growing mix to get the right planting height. Using the tying in wires, find possible points to secure the wires to the root system, either by inserting a chopstick into the root ball or securing over a non visible root. Use multiple fixing points to secure the tree. Do not cut the wires yet as this step is only a temporary fix until finally finalizing after adding the growing mix.

Step 8: Add growing mix into the pot layer by layer. Using your hand as a guide to keep your place, push the mix into the crevices with a chopstick. Work the mix from the trunk line outwards to the pot edge. Make sure to angle the chopstick towards the base to get the mix under the base and into the root ball. Keep rotating the pot pushing the mix into the root ball and adding more where necessary until it is sufficient.

Step 9: Tighten the tie in wires finally and make sure they are positioned correctly. Cut off any excess wire and cover so the wire is not visible. Water thoroughly to get the growing mix completely saturated. Leave for a few minutes in the shade to drain before applying the Chilean Sphagnum moss.

Step 10: Apply Chilean Sphagnum moss to the entire surface of the pot. We keep the finely sieved moss in a bucket ready for use. Add sufficient handfuls of the moss to water and allow to soak up the water for 5 minutes. Squash between your hands to create a type of burger patty like shape of about 5mm thick. Apply this to the entire surface, filling up any spaces as you go.

Water once again thoroughly to soak the entire area of Chilean Moss and the growing mix.


Aftercare is vitally important to the establishment of the tree and initial recovery period. The tree needs to be protected from:

  1. Excessive heat and direct sun

  2. Overwatering and drought conditions

  3. Heavy winds that can cause leaf burn

  4. Movement from wind, animals and excessive handling

A suitable place needs to be prepared ahead of time to protect the trees during the first 2- 3 weeks after repotting. Look for an area that is secluded with wind breaks and a shaded roof or dappled light under trees. A greenhouse that can be closed with high humidity will be ideal. Keep an eye on the tree twice a day to make sure all is well.

In Part 3 of this Blog series....

The next part of this blog series will tackle how to fertilise your trees, what fertiliser to use with evergreen and deciduous trees. How to mix different fertilisers, pesticides and fungicides together. And much much more...

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