Repotting the maple before the first frost
The little acer has been in the same pot for four years, and this summer it finally said so. Leaves smaller than last year, the whole thing drying out by mid-afternoon however much I watered it. When I tipped it out, the rootball came away as one solid felted mass in the shape of the pot, with barely any soil left in it at all.
The mix
I have stopped buying bagged compost for these. What works on the balcony, in a pot that has to survive both August sun and February wind:
- two parts sieved loam, the heavy stuff, for something to hold on to
- two parts fine bark, which keeps it open long after peat would have collapsed
- one part sharp grit, more if the pot has no feet under it
The point of all three is drainage. Acers in pots die of wet feet in winter far more often than they die of drought in summer, and by the time the leaves tell you, the roots have been sitting in cold water for months.
On not making it neat
I teased out maybe a third of the old roots, trimmed the worst of the circling ones, and left the rest alone. Years ago I would have combed the whole thing straight and trimmed the top to match. Now I do the minimum that lets it grow and leave the shape to the tree.
The best-looking maple on this balcony is the one I have interfered with least.
It went back into a pot two sizes up, not four — an over-large pot holds water the roots cannot reach, and you are back to the same problem from the other direction. Watered once, hard, then left alone. It will not do much before spring, and that is the whole idea: get it settled while the soil is still warm, and let the first frost find it already at home.