Repot Bonsai Trees
Bonsai trees, like other plants grown in containers, need to be regularly re-potted. Re-potting keeps the tree healthy by replenishing the nutrients in the soil, regulating root growth, and keeping the soil from getting too compacted. Learning how to re-pot bonsai trees will provide you with an essential skill when undertaking bonsai as a hobby. This learning process will also increase your general understanding and appreciation of your plant's health.
Steps
- Determine when your bonsai needs to be re-potted. The primary reason for re-potting a bonsai tree is when its root system begins to choke itself off. To determine whether or not this is happening, gently lift the entire tree from its pot. If the roots have begun circling around themselves, you need to re-pot. Eventually the roots will grow thick enough to displace all of the soil within the root system, and the tree will starve.
- Pick the right time of year for repotting your plant. Repotting should ideally be performed in early spring. At this time, the tree is not under the pressure of maintaining full foliage, and thus will be subject to less of a shock by repotting. The vigorous growth that begins in spring will also help the plant to heal any damage caused through repotting.
- Remove the old soil from the tree's roots. Once you have lifted the tree from its pot and decided to repot it, you'll need to remove as much of the old soil as possible. Knock the soil out of the root system either using your fingers or a specialized tool called a root hook. Gently disentangle the roots if they have grown thickly together.
- Remove some of the bonsai tree's roots. After untangling the roots, prune back some of the longer ones to keep the tree from outgrowing its pot. At this point, you should also remove any roots that appear to be rotting. As a general rule, avoid removing more than 25 percent of the tree's total mass of roots.
- Reposition the tree in its pot. When the roots are trimmed, gently lower the tree back into the pot. Fill the pot to the brim with your desired potting mix. Work the soil into the root structure so that there are no air pockets remaining between the roots.
- A typical bonsai potting mix will consist of akadama, gravel, and compost in about a 2-1-1 ratio. Akadama is a special kind of granular clay produced especially for potting bonsai trees. You may need to adjust this ratio depending on your climate and tree species.
- Water the bonsai tree. Watering the tree after repotting will help the soil to settle. Keep the tree protected from strong winds for a month or so after repotting.
Tips
- Young bonsai trees will generally need to be re-potted every year or every other year. Mature trees should be re-potted once every 3 to 5 years.
Warnings
- Do not remove all of the soil if re-potting a pine tree. Removing the soil will also remove the mycorrhizal fungus that helps keep the tree alive and healthy.
Things You'll Need
- Bonsai tree
- Container
- Root hook (optional)
- Pruners
- Akadama
- Gravel
- Compost
- Water
