Abstract: A modular greenhouse system for permitting a greenhouse of desired size to be created in a desired location includes a container defined by a plurality of panels removably coupled together and forming a perimeter wall. Each of a plurality of locking pins is engageable to the panels of the container. Each of a plurality of stanchions slidably receives a portion of the locking pins extending upwardly from the panels. Each of a plurality of ceiling joists is coupled to a pair of the stanchions opposite the container and extending across a width of the container. Each of a plurality of spanners extends between and is engageable to the ceiling joists and is configured to maintain positioning of the ceiling joists.