Acer trees or Japanese maples are beautiful trees ideal for pots, not only because they are slow growing but also because they can very much be enjoyed by those with small yards or gardens despite the limitations their property might have. Also, the best time to be repotting your Acer tree is at the start or end of winter. 

Reasons for repotting an Acer

You may choose to re-pot your Acer palmatum for various reasons:

  1. Japanese Maple Acer trees are often repotted to replace the fresh potting soil and provide it with fresh soil. This is an important process that facilitates these trees in getting the necessary nutrients they need to grow.
  2. It is a norm for Acer trees to grow beyond the pot they are in. It is easily seen when the tree becomes disproportionately heavy at the top or you can simply see it outgrowing the container causing roots to emerge from different parts of the plant. With this, it is obvious it needs more space to grow and expand.
  3. You can stimulate the growth of your smaller sized Acer trees by transferring them to a larger pot. If you keep your Acer in a tight container, it will simply adapt to it by growing much slower than it should. Hence, repotting your Acer in a large container or pot is beneficial as it gives it more room to thrive. It will encourage this lovely tree to grow larger at a faster rate. 
  4. The roots of your Acer tree can become entangled when they become too large to fit the container that they are in. In such a case, you may see the tree’s roots break out of the holes. This is a way to let you know you need to re-pot your tree.

 

Repotting Your Acer: A Step-by-Step Guide

Follow these steps if you want to know how to repot your Acer tree:

  1. Choose the right time: The ideal time to repot your Acer is during early spring (April) or early fall (September), when the tree is not actively growing and is less susceptible to transplant shock.
  2. Select an appropriate pot: Choose a pot that is approximately twice the volume of the tree’s root ball (if potting up from having no pot) made of stone or terracotta for better insulation and moisture retention. Ensure that the pot has proper drainage holes and a wide base for stability. If you’re repotting, choose a pot that is only a few inches bigger than the one you have.
  3. Prepare the new pot: Place a layer of drainage material, such as gravel or broken terracotta pieces, at the bottom of the pot to prevent soil from blocking the drainage holes. Add a layer of fresh, well-draining, acidic potting soil with a pH of 5.5 to 6.5 to the pot, leaving enough space for the root ball.
  4. Remove the Acer from the old pot: Gently lay the tree on its side and carefully remove it from the existing pot. It may help to tap or squeeze the sides of the pot to loosen the root ball. If the tree is pot-bound or the roots are tangled, use your fingers or a root hook to gently tease the roots apart.
  5. Inspect and trim the roots: Examine the root system for any signs of disease, damage, or circling roots. Use clean, sharp pruning shears to trim away any dead, damaged, or overly long roots.
  6. Position the Acer in the new pot: Place the tree in the center of the new pot, ensuring that the top of the root ball is slightly below the rim of the pot. Spread the roots out evenly over the layer of soil.
  7. Add more soil: Fill in the gaps around the root ball with fresh potting soil, gently tamping it down to eliminate air pockets. Make sure the soil covers the roots completely, but avoid burying the trunk. Get suitable soil consisting of 50% moist but well-drained soil and 50% compost. Mix them while breaking up large chunks that may be in the mix. You may also get some decorative mulch if possible.
  8. Water thoroughly: After repotting, water the Acer thoroughly to help the soil settle and eliminate any remaining air pockets. Allow the excess water to drain out of the pot.
  9. Place in a suitable location: Position your potted Acer in a sheltered spot with dappled sunlight or partial shade, protected from strong winds and frost. Monitor the tree closely for a few weeks to ensure it is adapting well to its new pot and environment.
  10. Ongoing care: Continue to provide proper care for your Acer, including regular watering to maintain slightly moist soil, fertilising with a slow-release, balanced fertiliser, and pruning as needed to maintain the desired size and shape.

What size pot for an Acer tree?

Selecting the appropriate pot size for your Acer tree is essential for its health and growth. Ideally, choose a pot that is approximately twice the volume of the tree’s root ball. This provides the tree with sufficient space to grow while preventing potential issues such as root rot caused by excess soil and oversaturated conditions. When selecting a pot, ensure that it has adequate drainage holes to prevent waterlogging.

What pots are best for an Acer?

Stone or terracotta pots are highly recommended for Acer trees for a few reasons. Their weight, compared to lighter containers, offers stability and prevents the pot from being blown over in strong winds. Additionally, stone and terracotta pots provide better insulation and moisture retention, promoting a healthier root system. When choosing a pot, make sure the base is wide enough to provide proper support and stability.

Do Acers need big pots?

While Acers do not necessarily require large pots, it is important to provide them with enough space to grow and develop a healthy root system. As a general guideline, the pot should be around double the size of the root ball. This allows for adequate growth without causing issues like root rot from oversaturated soil. However, avoid using an excessively large pot, as it can lead to waterlogged soil and increased chances of root rot.

What is the best container for a Japanese maple tree?

Containers made from natural materials, such as clay, ceramic, and wood, are ideal for Japanese maple trees. These materials offer better aeration and insulation for the roots, creating a healthier environment for growth. When potting a Japanese maple, use a porous, fast-draining, acidic soil with a pH of 5.5 to 6.5. This soil type will cater to the tree’s fine, fibrous root system. To promote proper drainage, use pot feet to elevate the container and keep the drainage holes clear of debris.

How often should you repot an Acer?

Repotting your Acer tree is necessary to promote healthy growth and prevent the roots from becoming pot-bound. Typically, potted Japanese maples should be repotted every two to three years. This timeframe allows the tree to grow and develop a healthy root system while minimising competition from other plants for water and nutrients.

Do Acers like to be pot-bound?

Japanese maples, or Acers, are well-suited for pot cultivation due to their slow growth and stunning visual appeal. Although they can tolerate being slightly pot-bound, it is essential to repot them periodically to promote healthy growth and prevent root circling or girdling. Regular repotting also ensures that the tree receives adequate nutrients and maintains a balanced root-to-shoot ratio.

When should I move my Acer to a bigger pot?

To maintain the health and growth of your Acer, repot it into a slightly larger container every few years. The best times to repot Acers are in early spring (April) or early fall (September), when the tree is not actively growing and is less susceptible to transplant shock. During repotting, inspect the roots for any signs of disease or damage and trim away any dead or damaged roots.

Where should a potted Acer be placed?

The ideal location for a potted Acer depends on the specific variety and its light requirements. Generally, Acers prefer a sheltered spot with dappled sunlight or partial shade. Direct sunlight, especially during hot summer months, can scorch the delicate foliage, while excessive shade can lead to reduced leaf coloration. Additionally, select a location that is protected from strong winds and frost to prevent damage to the tree.

Why is my Acer struggling in the pot?

There could be several reasons why your Acer is struggling in its pot. Excessive exposure to dry winds, direct sunlight during hot summers, or frost during winter can all negatively impact your Acer’s health. Moreover, overwatering can be detrimental to your tree, as Japanese maples do not thrive in waterlogged soils. To improve your Acer’s condition, ensure that it is placed in a suitable location with dappled sunlight or partial shade, protected from harsh weather conditions, and watered appropriately to maintain slightly moist but not waterlogged soil.

Do potted Acers lose their leaves?

Yes, Acers are deciduous trees, which means they naturally shed their leaves during the winter months. As the temperatures drop and daylight hours shorten, Acers will enter a dormant phase, losing their leaves in preparation for the colder season. This is a normal process and allows the tree to conserve energy during winter. Once spring arrives and temperatures begin to rise, your Acer will produce new leaves and resume active growth.

How tall do Acers grow in a pot?

The height of an Acer tree grown in a pot depends on the specific variety and the growing conditions provided. For example, the Acer palmatum dissectum Garnet is a popular choice for its vibrant red foliage that lasts throughout the growing season. This hardy tree is well-suited for small gardens or pots and typically reaches a maximum height of approximately two meters. However, the tree’s growth can be controlled through regular pruning to maintain a smaller size or desired shape.

 

Further Reading

We have lots of other helpful content for Acers, such as common questions we have been asked such as:

Read more about Acer Palmatum here

Other Acer’s you might be interested in

Acer Brilliantissimum, Acer Feeds, Acer Jerre Schwartz, Acer Altropurprueum, Acer beni maiko, Acer Bi Hoo, Acer Bloodgood, Acer bonsai, Acer Butterfly, Acer Deshojo, Acer dissectum, Acer dissectum Firecracker, Acer emerald lace, Acer fireglow, Acer garnet, Acer katsura, Acer little princess, Acer orange dream, Acer Osakazuki, Acer Phoenix, Acer Sango kaku, Acer Seiryu, Acer Shaina, Acer Shindehojo, Acer Skeeters Broom, Acer Taylor, Acer Trompenburg, Acer Ukigumo.

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Last Modified: May 3, 2023