Growing Japanese Maples in pots is a very common practice. However, the tree constantly grows in size and needs to be replanted from time to time. In this article, you will learn step by step how to transplant a potted Japanese Maple.
Choose the right pot
The new pot should be two to three inches wider and the same amount higher than the previous one. Avoid transplanting a maple into a pot that is too large, as it will leave the roots surrounded by a lot of soil and may cause root rot in rainy weather.
Make sure that there are drainage holes at the bottom of the pot. The minimum number of holes is 3 to 4 with a diameter of about half an inch. If there are not enough holes, drill more of them.
Regarding pot material, you can use either clay or plastic pots. However, clay is heavier and may crack in winter. At the same time, plastic is more manageable and not as expensive.
Use only quality pots to avoid problems with moving the maples. The thicker and more flexible the plastic from which the pot is made, the better.
Avoid using pots with a drip tray or self-watering pots. Excess water should flow out quickly and not stagnate around the roots.
Prepare the soil
The best substrate for potted Japanese Maple is a well-drained and nutritious substrate on an organic basis. Water should not stagnate in the substrate, but at the same time the substrate should not dry out quickly. Organic matter, among other things, will serve as an excellent fertilizer.
You can use potting soil mix from the store. Usually, such substrates meet all of the above requirements. The main thing is to choose a quality and well-known manufacturer. You should not save money here, because otherwise, the maple may suffer.
You can also go the other way and create your own substrate. To do this, take one part of native soil from your garden and add to it one part of quality compost and one part of pine bark nuggets. After that, mix it all up well.
If you want everything to be perfect, test the soil for pH levels. There are special kits available for this purpose. If the pH is above 7.0 then you should add some soil acidifier. If the pH is below 5.5 add some garden lime to the potting soil.
Choose the right time
The best time to transplant a potted Japanese Maple is early spring. It is important that the tree is still dormant. In this case, transplanting will be the least painful.
Don’t transplant in the middle of winter as the roots are sure to get damaged when you take them out of the pot. Damaged roots can rot by the spring. But if you transplant it on the eve of the growing season, the tree will quickly regenerate its root system.
Also, avoid transplanting in midsummer because the heat can kill a newly transplanted maple.
Give preference to a cloudy and wet day over a dry and sunny day. If it hasn’t rained in a while, water the maple one day before transplanting. Mornings and evenings are the best times of day for this purpose.
Trim the roots
One of the things you might want to do is cut some of the roots. Very often a potted maple will develop a large root system and the roots will begin to grow in a circle along the wall of the pot. This phenomenon is called root-bound and it needs to be corrected.
Grasp the bottom of the trunk and gently pull the maple out of the pot. If you see root bound, you need to cut these intertwined roots.
If there is nothing wrong with the roots, don’t touch them and plant the maple as is.
Use a sharp knife or saw to remove the root-bound. First, cut off the bottom layer of the root ball about 1 inch thick.
Next, cut the sides of the rootball as if you were slicing bread. Cut the slices no more than 1 inch thick. If some of the roots are too long, shorten them with scissors.
After pruning, the root ball should shrink by 10-15% but no more. Also, be careful not to shake the soil off the roots.
Plant a Japanese Maple in a new pot
The next step is to plant the Japanese Maple in a new pot. Put some stones in the bottom of the pot. This is to improve the drainage in the pot and to prevent the soil from washing out through the drainage holes.
The size of the stones should be a bit larger than the drainage holes, but do not use too big stones. The layer of stones should be about 1-2 inches but no more.
Next, place the maple in the pot so that the ground surface is about an inch below the edge of the pot. Add some soil to the bottom of the pot if necessary.
Fill all the empty space in the pot with soil and tamp it down a bit with your fingers. Add more soil if needed.
Water the maple well with 1-2 gallons of water, or more if the tree is large. In the next chapter, you will learn how to properly care for the Japanese Maple in the first year after transplanting.
If the weather is sunny and hot after transplanting, move the maple to partial shade. This will prevent the pot from overheating and the soil from drying out quickly.
Mulch the surface of the root ball in the pot with organic material. Pine bark or wood chips are ideal for this. The layer of mulch should be about 1-2 inches, but keep a 1-inch gap between the mulch and the trunk.
Monitor the moisture content of the potting soil at all times. As soon as it dries out more than an inch, water with enough water.
Fertilize the tree with a slow-release fertilizer immediately after transplanting. Avoid fertilizers that contain too much nitrogen. One application per year is sufficient.
For more information on caring for potted maples, see Can Japanese maple survive in pots?