Approx 6years ago I inherited a lovely Acer from an old forum member Terry Evans. Terry was a wonderful gardener, which I am not ,although I am learning. The Acer is doing well but I think the pot it is in is getting too small for it,and I am wondering if anyone could tell me when I should repot it. At the moment it is looking lovely.It is about 4ft 6 tall and has a lovely spread with lots of beautiful red leaves. I feed it regularly. Hoping one of the forum members can give me some advice.
How To re-Pot Japanese Maple Trees (acer palmatum)
The best time to re-pot Japanese Maples is mid spring time. The idea is to re-pot before they break into leaf. A good time is late March in your area. It's best to leave the repot to that time because Japanese Maples are delicate trees when grown in pots. Make sure the plant was watered well in the previous couple of weeks.
The "soil" you need is half John Innes Number 3 and half ericaceous compost. Just ask at any garden centre or nursery and they will know what you mean. Japanese Maples dislike alkaline soil and produce the best leaf colour in a slightly acid soil.
It's essential to put some rubble or stones at the bottom of the pot to ensure good drainage, especially in the winter. Nothing will damage an acer quicker than waterlogging.
The new pot should be 5cm (2ins) or so larger than the old pot.
Tip the pot sideways taking care not to damage the leaves. Gently pull the maple from the pot using the base of the main stem as near to the soil as possible. Place a layer of soil over the rubble in the new pot and place the maple in the new pot. The aim is to keep the top of the soil at the same level as it was before. So adjust the amount of soil in the bottom of the new pot to do that.
Fill around the edges with the new soil and gently firm it in. Water well
Margaret did a search and found this, hope it is of use to you