Dear Gianni,

bonsai are small saplings, kept small through a series of care; among these, life in a small pot allows us to keep the root system small, and therefore also the plant. By moving a bonsai from the pot to the ground, we allow it to begin to develop naturally again, and therefore your oak, over the years, will tend to rise and develop like a normal oak tree, reaching several meters in height. a plant placed in the ground allows us to give it much less care, compared to a bonsai: the large amount of soil allows us to water only sporadically, while a small bonsai pot often needs very frequent and regular watering. you have to get your plant back to being a bonsai is to limit its root development then you can place slabs around the roots, deep, so that they don’t develop as you like. Or you can periodically pull the oak out of the ground and prune the roots, about one-three of their length. This operation is carried out at the end of winter, when the plant shows itself at the beginning of the vegetative period, and already has clearly visible buds; in any case it is avoided to ruin the taproot, that is the largest root that keeps the plant erect, which generally develops perpendicular to the ground. In addition to this, you can try the periodic defoliation of the plant, usually done in May, when the plant is still in full vegetative development; with a scissor cut the petioles of crica half of the leaves, starting from those placed in the most external part; in this way the sapling is stimulated to produce new ones, all together, which generally will tend to be smaller.