I would like to explain your question on a case-by-case basis:
1. The land on which the greenhouse is built must be legal, that is, the land does not conflict with the nature of the planned land (that is, the land You have the right to use it (it is legal agricultural land itself and meets the requirements for other land) (rural land is collectively owned, and you build it on land assigned to you or contracted by you);
2 .The size of the greenhouse must be built in a legal way. I don’t know the specific size requirements (but it must not be built into something else), and the construction process and the completion of the construction must not cause adverse effects on others;
3. If the locality or village has other regulations, it should also comply with the requirements.
If it meets the above three points, it should be legal.