Maples are among the most cultivated plants as outdoor bonsai; the many varieties of acer palmatum are preferred, thanks to the already reduced size of the foliage compared to the other species of maple; these plants can also present different types of foliage, many of which have very pleasant colors, some all year round, others only in autumn, before the fall.
They are preferably outdoors, as they are plants that can also be found in our garden in the open ground; however, we keep in mind that bonsai is grown in a small portion of land, and will therefore be much more sensitive to temperature than a garden plant.
So we grow our bonsai in a sunny place during the periods of the year when the climate is mild, then from September to October, until the beginning of spring; we therefore proceed to move the pot into a shady but bright place during the hottest weeks of the year, to prevent the cultivation substrate from drying up completely within a few hours, often causing part of the foliage to dry out. During the winter generally these plants should not suffer from the cold, we can therefore place them outdoors, in a very sunny place; to avoid however that intense and prolonged frosts cause the freezing of all the ground bread, we can cover the vase with woven fabric, and, if the winter is particularly rigid, we can extend the covering to the whole plant, or even move it to a cold greenhouse.
Maples are fairly easy growing essences, once you find the best place to display them; these are deciduous plants, so from October, when the leaves fall, until the spring, the plant is struck by vegetative rest, so it is not infested with fertilizing and watering. Instead we will proceed to regular watering from spring to autumn, trying to keep the soil always slightly humid, even leaving it slightly dry for short periods of time, but only if the climate is mild. We will insist on watering especially during the hottest days of the year, since even just a day with the soil completely can lead to a partial or total drying out of the foliage.
Especially during the warm months, remember to keep the maple in place with high humidity; we can increase the environmental humidity even by frequently vaporizing the foliage, or by placing the vase in a tray filled with gravel, containing at least a couple of centimeters of water, which with evaporation will increase the humidity.
From April to September we provide very frequent fertilizations, but with contained doses of fertilizer; or we mix small doses of slow release fertilizer, specifically for bonsai, on the cultivation soil. Recall that bonsai are grown in small portions of land, which is why they are affected by any modification, even small, in this substrate, so it is essential to avoid over-fertilizing, and strictly adhere to the instructions on the fertilizer package chosen by us.
Maple - Acer palmatum: Extraordinary maintenance
To obtain a well-balanced bonsai, besides watering, we will have to periodically think about pruning, as happens with other bonsai essences, even with maples we will practice two types of pruning; one is the training pruning, which takes place in autumn, when the plant has already lost its foliage: this type of pruning is suitable to maintain the crown of the shape we have chosen for our bonsai, and it must be practiced eliminating the intertwined branches , and those that come out of the crown too much.
A second type of pruning is instead called maintenance; this pruning is carried out during the vegetative period, and guarantees a compact development of the plant and the production of small sized foliage: we periodically remove the apex of the newly formed branches, leaving 2-3 leaves.
Since most of the species have small leaves of significant size, it may be necessary to stimulate the plant to produce a second "generation" of leaves, so that the commitment proffered by the plant causes the reduced size of this generation; for this reason in late spring, when the plant has already produced the foliage and the climate is not too hot, we can remove all the foliage of the maple, which will thus be forced to produce new leaves, generally smaller bunes than the previous ones.
Every year, or at least every two years, we invade our bonsai maple, especially if the plant is very young; this operation is carried out in autumn, pruning part of the roots; we remember that the plants recently repotted fear the cold a little more than the potted plants for a long time, so let's remember to put our maple recently repotted in a sheltered place for the winter, or if possible in a cold greenhouse.