I just found this info today:
"The name of this plant was given to French botanist Michael Begon. The homeland of tuberous begonias is Central and South America - areas with warm tropical tropics. Several hundred varieties of varying height, plant type, size and shape of the leaves, and the structure and color of the flowers were obtained. Varieties are divided into large and medium-sized and small-sized, with the latter being usually begonias with drooping shoots. The latest varieties are offered as a series, in which the varieties differ only in the color of the flowers, and the remaining varieties are identical. The underground part is brown, kidney-shaped tubers covered with traces of old roots. The upper part of the tuber is concave and there are new shoots. Flowering is from June to autumn. Begonias do not winter in the ground and therefore are typically a seasonal, summer plant whose tubers are planted in May and are already dug in late September. The best place is the area slightly shaded, protected from the wind. The soil should be humus, permeable, moist. Tubers are planted every 25-30cm, covering them only with a thickness of 2cm. Tubers can also be planted in pots, already in March, and ground to exaggerate when the fear of spring frost.
The Rich assortment of varieties makes it possible to find suitable begun for growing in the ground, in groups on the lawns, and in various types of containers. These can be balcony boxes, bowls, as well as standing and hanging pots. Planted begonias with drooping shoots must be protected from the wind because the shoots are brittle and easily break."
Not sure whether it's true or not but I think I can grow them from there