Growing acers in pots – everything you need to know
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Acer trees (also known as Japanese maples) are compact trees suitable for growing in pots. Although some varieties do grow high and wide, they’re so slow growing that you can enjoy even these acers in pots before they get too big. These hardy trees are easy to care for in containers.
Choosing your acer tree
You have a choice of many varieties of acer trees, some specifically for growing acers in pots. The Acer Japonicum varieties remain as small spreading trees. If you’re looking for more of a shrub-like tree, take a look at the Acer Palmatum types. These grow broader than they do tall, giving a bush-like appearance.
Then you need to decide what colour leaves you want to feature on your tree. Acer leaves change colour through the growing season. New leaves start from yellow and lime green through to pink; autumn colour ends up at bright yellow through orange to intense red.
Choosing your pot
You don’t need a very deep pot for your acer tree as they like their roots to be close to the surface. However, a wide pot is preferable as acer trees like a lot of space around them.
Terracotta planters are nice and heavy for stability. They’re also frost-proof which helps to protect your tree on cold nights. However, this natural material dries out quickly, especially on windy days. You need to keep to a regular watering schedule and to keep an eye on the moisture level in-between times as well.
Ceramic pots are much the same as terracotta pots. For both these materials, however, you may need to make additional holes in their bases as acers need a well-drained soil. Doing so may prove to be quite difficult.
Plastic containers are easy to drill drainage holes into. However, they’re quite lightweight and may topple easily. You need to weight them down with rocks in the bottom to hold them, and your tree, upright.
The right size pot
The right size of container for your acer tree is ideally one that’s two to three times the width of the extended roots. But that’s not easy to judge if your tree is still in its original container.
As a rule of thumb, select your first container so that it’s three times as wide as the pot the tree came in. This assumes that the root ball is the size of that container. And the new pot gives you plenty of room to spread the roots out without being too big.
Whichever pot you choose, place some shards of terracotta or some small rocks in the bottom. This stops the compost from leaking out onto your deck or the ground below.
The right soil for acer trees
Although acers in pots aren’t too fussy, they do prefer an acidic soil. You can achieve this through using an ericaceous (acidic) compost. Mix this in with your own organic compost for a light but not-too-open soil. The soil needs to drain well but you don’t want all the water to run straight through.
Use mulch on top of the soil to retain the moisture in it. If you choose organic mulch, make sure that the mulch doesn’t touch the tree trunk as that damp and dark environment could lead to disease for the tree. Perhaps consider an inorganic mulch such as gravel instead.
Potting the acer tree
I have a handy article all about this. Visit How to repot an acer tree?
Watering and feeding
Japanese maples growing in containers tend to dry out quite quickly. Establish a watering routine but keep an eye on how dry the soil is in-between times. Newly potted trees, particularly in dry spells, need quite a bit of water. Hot dry spells also necessitate more watering than usual.
If your acer leaves are becoming scorched, that is brown around the edges and tips, it could be because of over- or under-watering. Reflect back on your watering routing to figure out which is the problem and adjust accordingly.
Acer trees don’t need much fertilising. One application of fertiliser for acid-loving plants in the spring should be enough for the entire growing season.
Acer trees, especially those planted in containers, don’t respond well to frost. If the weather forecast is for a cold night, move the container somewhere warmer and sheltered. A corner between outside walls is suitable for their well-being. In addition, wrap the tree in several layers of horticultural fleece to keep it warm and away from any freezing water. It’s also a good idea to raise the container above the ground, perhaps upon bricks, so the cold doesn’t seep in through the bottom of the pot.
You can learn more about how to protect an acer tree over winter here
Frost will cause the leaves to scorch but there are also other reasons for this too, learn more about why your acers might have scorched leaves in this guide here.
If you have sort of acer plant problems, maybe diseases, check out my guide on Acer problems here