Repotting is a critical aspect of bonsai care that ensures the tree’s growth is not restricted and helps maintain its health and vigor. This guide will walk you through the process, from understanding when to repot to the actual steps of repotting.
Recognizing When to Repot Your Bonsai
The need to repot your bonsai tree is dictated by several factors, including the species of the tree, the size of the pot, the age of the tree, and the specific growing conditions it’s subjected to. As a general rule, younger trees tend to require repotting every two years due to their rapid growth rate, while older, more mature trees may only need repotting every three to five years.
The most reliable indicator that your bonsai tree needs repotting is the state of its root system. Over time, as the tree grows, the roots can become densely packed and begin to circle around the root system, a phenomenon known as becoming ‘root-bound’. This not only restricts the tree’s growth but also impedes the soil’s ability to percolate water effectively.
Moreover, the potting medium itself can degrade over time, becoming more compact and less efficient at draining water, which can lead to root rot and other health issues for the tree.
To assess whether your bonsai tree needs repotting, it’s advisable to check the roots in early spring, just before the onset of the growing season. If the roots are still well contained within the soil and not showing signs of being root-bound, you can safely postpone repotting until the following year. However, if the roots are densely packed and circling the root system, it’s time to give your bonsai tree a new home.
Choosing the Right Bonsai Pot
Choosing the right pot for your bonsai tree is an essential step in creating a harmonious bonsai display. The pot you choose should not only be functional but also aesthetically pleasing, complementing the tree’s attributes such as the flowers, bark texture, trunk thickness, and leaf and needle sizes and shapes.
Different Types of Pots
Bonsai pots can be made from various materials, including plastic, ceramic or porcelain, concrete, metals, clay, mica, stoneware, and wood. However, it’s best to avoid metal pots as they may release toxins. A classic type of bonsai pot is made of porcelain or ceramic, genuinely stoneware burned. These pots absorb and hold no water in their material, which is crucial for the health of your bonsai trees.
Glazed and Unglazed Pots
Glazed colors of bonsai pots are recommended for fruiting and flowering bonsai trees. For evergreen bonsai trees, such as pine and juniper, the muted tones of gray and brown are highly recommended. Glazed bonsai pots usually have designs such as flowers or birds. Flowering or deciduous bonsai trees are best complemented by being displayed or planted in glazed bonsai pots having soft hues, like cream, green, or light blue. Unglazed bonsai pots in colors brown, gray, and red clay are somber hues, which are the best complement with evergreen and conifer bonsai trees, portraying the harsh environment of the tree’s natural habitat.
Vertical and Horizontal Pots
The shape of the bonsai pot must relate to the bonsai tree’s style. Those with straight trunk style bonsai trees balance better when they are in rectangular bonsai pots, while soft-lined or curved trunk bonsai trees look better in a round, oval, round-cornered, or a rectangular pot. A rugged and powerful looking bonsai tree is best planted in a bonsai pot with hard angles.
Trays and Training Pots
There are two types of basic bonsai pots, display pots, and training pots. While your bonsai is still in the training phase, it should remain in a functional and practical training pot. Display pots are typically made out of wood, plastic, or mica. Your bonsai training pot should provide enough space for a healthy and stable root system to grow, in order to achieve your bonsai tree’s desired trunk thickness as well as good branching. Bonsai training pots have large drainage holes, ensuring that the water doesn’t pool at the bottom, that can waterlog the root system and possibly kill your bonsai tree.
After completing the critical training phase, and it has fully developed, your bonsai can be repotted in a display bonsai pot. Display bonsai pots are generally more aesthetically appealing. They are typically made of ceramic with either a glazed or shiny finish or an unglazed or matte finish. The ceramic bonsai pots are frost-proof. Display bonsai pots can be attractive, and it’s important not to select a bonsai pot that overshadows the beauty of your precious bonsai tree. Instead, select one that will even enhance the beauty of your bonsai tree.
Preparing for Repotting
Before you begin the repotting process, prepare the bonsai pot. Place a plastic mesh over the drainage holes, held in place by a piece of wire. This prevents soil from washing out of the pot while still allowing water to drain.
Next, prepare the soil mix. Bonsai trees require a specialized soil mix that differs significantly from regular potting soil or garden soil. The soil mix for bonsai needs to provide excellent drainage, retain sufficient water, and offer good aeration. A common mix includes akadama, pumice, and lava rock.
Akadama is a hard-baked Japanese clay specifically produced for bonsai purposes. It provides excellent water retention but needs to be replaced every two years as it begins to break down. Pumice is a soft volcanic rock that absorbs water and nutrients quite well. It helps retain water and allows the roots to ramify very well. Lava rock also helps retain water and create a good structure when part of a Bonsai substrate. Roots can’t grow into the Lava rock.
These components are often used in a ratio of 1/2 akadama to 1/4 pumice to 1/4 lava rock. This mix ensures that the soil drains well, preventing waterlogging and root rot, while also retaining enough moisture to support the tree’s needs.
It’s important to note that regular garden soil or potting compost is not suitable for bonsai trees. These types of soil can become compacted and hard when dry, which can impede water percolation and root growth. Furthermore, most potting composts absorb water very poorly once they are completely dry, which can lead to watering difficulties.
When using your soil mix, ensure that your bonsai is planted in a proper, well-draining bonsai soil, to prevent a buildup of salts. When using solid fertilizer, it helps to use fertilizer covers to make sure the fertilizer stays in place. Never overfeed your trees, as this will have serious consequences for their health.
The Repotting Process
How to Repot a Bonsai Tree?
1. Removing the Bonsai from the Pot
Carefully remove the bonsai tree from its current pot using a root hook. Inspect the roots and decide whether repotting is necessary based on their formation.
2. Teasing Out the Old Compost
Use a chopstick to carefully remove the old compost, ensuring you do not damage the roots. Trim any roots that have grown too long.
3. Positioning the Bonsai in the New Pot
Place a layer of soil in the bottom of the pot before positioning the plant. Add more of the growing medium around the tree, ensuring it reaches the bottom edges of the pot.
4. Watering
After repotting, water the tree thoroughly. This settles the soil and fills up any remaining air pockets.
Caring for Your Bonsai After Repotting
After repotting, protect the tree from strong winds and sun for about two months. Start fertilizing one month after the repotting to help the tree recover and continue its growth.
Repotting your bonsai tree is a vital part of bonsai care. By understanding when and how to repot, you can ensure your bonsai tree thrives and continues to captivate with its unique charm. Happy repotting!
Bonsai Repotting FAQs
When should I repot my bonsai tree?
The frequency of repotting a bonsai tree can vary greatly depending on the species, size of the pot, age, and growing conditions. Younger trees typically require repotting every two years, while older, more mature trees may only need repotting every three to five years. The key indicator that it’s time to repot is the root system. If the roots begin to circle around the root system, it’s time to repot.
What type of pot should I use for my bonsai tree?
The choice of pot is crucial for the overall composition of your bonsai. The pot should be the same height as the width of the ground root, which is typically one to two-thirds of the tree’s height. The style of the pot is largely up to your personal taste, but it should complement your bonsai tree’s aesthetics.
What type of soil mix should I use when repotting my bonsai tree?
A good bonsai soil mix should provide excellent drainage while retaining enough water to supply the tree. A common mix includes akadama, pumice, and lava rock. These components are often used in a ratio of 1/2 akadama to 1/4 pumice to 1/4 lava rock. This mix ensures that the soil drains well, preventing waterlogging and root rot, while also retaining enough moisture to support the tree’s needs.
