Oak: large leaves

Question: oak: large leaves

I state that it is a bonsai that has been outside for almost 5 years, its habitat is in a tombstone, until last winter it was planted in the garden but inside in its original vase. in the fall the gardener suggested I plant it directly in the ground, the result is that this year I find myself having a bonsai with huge cocks ... what can I do?
thank you in advance
Giampietro Mariani

Answer: oak: large leaves

Dear Gianni,
bonsai are small trees, kept small through a series of treatments; among these, life in a small vase allows us to keep the root system small, and therefore also the plant. Moving a bonsai from the vase to the full ground, we allow it to start to develop again naturally, and therefore your oak, over the years, will tend to stand up and develop like a normal oak tree, reaching several meters in height.
I understand that a plant placed in the ground allows us to give it much less care than a bonsai: the large amount of land allows us to water only sporadically, while a small bonsai pot often needs very frequent and regular watering.
The only way you can get your plant back to being a bonsai is to limit its root development; therefore you can place slabs around the roots, in depth, so that they do not develop at will. Or you can periodically extract the oak from the ground and prune the roots, about one-third 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 presents already clearly visible gems; in any case we avoid ruining the taproot, which is the largest root that maintains the erect plant, which generally develops perpendicular to the ground. Besides this you can try with the periodic defoliation of the plant, it is generally practiced in May, when the plant is still in full vegetative development; half of the leaves are cut with a pair of scissors, starting from those placed in the most foreign part; in this way the sapling is stimulated to produce new ones, all together, which will generally tend to be smaller.