Abstract: Plant cultivation units include several tiers of cultivation beds in open baskets supported on trays extending between endless chains which couple a pair of drive pulleys to a pair of idler pulleys. The beds are driven about a generally vertical endless path at a speed sufficient to cause artifical air movement and to maintain a low air temperature differential between the top and bottom of the endless path; this permits greater vertical separation between the top and bottom of the path and greater growth area to floor area ratios. Hollow pulley shafts supply and withdraw air. A pair of pipes supply water and steam. A method of growing mushrooms includes two phases in a common housing: a pasteurization phase and a growth phase.