What is a Detached Medium?
Question
What is a detached medium, and what is its status regarding cultivation during the Sabbatical year?
Answer
A detached medium refers to greenhouses. This means that the medium on which the plants grow (soil/gravel/tuff/straw, etc.) is placed on rigid plastic sheets and covered on the sides with walls. It is considered like a non-perforated pot located inside a house. Some are lenient, considering that in this manner, there is no prohibition of labor and sanctity of the Sabbatical year for vegetables. However, in practice, one should be stringent because this permission is not clear, especially in greenhouses where the practice is to sow throughout the year. Also, the entire permission for growing in a house is because the house interferes with natural growth, but greenhouses facilitate growth. Additionally, large pots are considered as land.
Source
Azmera Lishimcha (Shemita, Issue 2).