Without no doubt the acer palmatum including all it's subspecies is one of if not the most
appreciated bonsais because of it's beautifully colored leafs. Depending on the season and region, the color changes from light green
to dark red. I will not explain the difference between all the subspecies mentioned above, the differences reside mainly in the form of the leaves,
the color they adopt in different seasons.
Light: Keep the acer palmatums in mid shadow, the fine leafs will be burnt in direct
sun. Be sure to keep the soil humid, this will reinforce the resistance against the sun.
Temperature and exposure: Trees should be protected from temperatures below 3° C, in fact
last year I lost some branches because the tree was exposed one only night to lower temperatures. It will also react with toasted leafs if
it's exposed to warm winds. As a counterpart a good ventilation must be assured to avoid diseases as red spider mite.
Pruning and cleaning: Always remove dry or fallen leafs. Pinching:
Like all acers, pinch the final part of the branches leaving only two knots. Lateral branches shut be left with only one knot. Pruning:
During the growing period, cut the branches leaving only two pairs of leafs per branch. Structure pruning is done in wintertime when the tree has no leafs.
Repotting / Soil: Repot every two to three years eliminating the half to 2/3 parts of the fine
roots and plant in a bigger pot. Acers looks good in oval low pots in dark green colors, or dark brown ceramic pots, always in circular and
semicircular forms. The mixture of soil I recommend is composed of 3/6 of compost, 1/6 of humus and 2/6 sand. Acid soils inhibit a good growth.
Wiring: The main season for wiring are is from June to August when the
tree is growing fast. Don't keep the wires for more than 5 months and protect the sensible branches with raffia.
Watering: Water abundantly in spring and summer and as always, reduce the
watering in winter. Be sure to shower or vaporize the trees as often as possible as they need a lot of humidity.
Fertilizer: Organic solid fertilizer must be applied starting in march, reducing
the dose during the hot summer days and stooping completely at the end of November. Never apply on recently repotted or affected plants.
Diseases: Acers can be affected by a lot of diseases and parasites, a lot
of them can be avoided keeping humidity high. I have had aphids and red spider mite which I eliminated keeping the whole tree under water
for some hours. If that doesn't help, apply a product in which you trust (Folithion for me is one of the best) always in very small doses.