During the first year of its growing, stevia is slowly developing and that is why it is appropriate to be grown as a perennial crop. In the conditions of the temperate zone, where Bulgaria is also situated, that is done through digging out its roots and storing them in a storehouse during the winter. After harvesting the leaves, the roots together with the soil left around them are placed in boxes on the bottom of which a soil layer of 3-5 cm is sprinkled, and after that some moist soil is placed so that on the surface only the cut stems are left. Stevia roots are kept under strict temperature control, no more then +8° С (otherwise they begin to sprout) and no less then +4° С (because they freeze) and air humidity of 80-85 % in a basement or a room without light. Suitable for their storing is the bottom part of a refrigerator if a constant temperature is kept there. In the next season when roots are planted in the garden, the speed of stevia development is significantly increasing in comparison with the plants which are grown from seeds.