Do I need a greenhouse to grow sporophytes?

No, sporophytes can be cultured in a C-Fern Growth Pod – well I suppose that is a teeny-tiny greenhouse! Use a 35 mm film canister (if they are still available), or equivalent. as a miniature pot or a small plastic water bottle. Once sporophytes outgrow these they can be transferred into and cultured in clear 2 L plastic soda bottles. Sporophytes require the same warm temperature, 28 °C (82 °F), and adequate light as needed for gametophytes.