The first greenhouse structures for propagation were specialized sunken or pit greenhouses. Mist propagation was not commercially on a routine basis until the 1950's.
Prior to that pit greenhouses provided a warm, high humidity environment for propagation.
Commercial greenhouse structures used in propagation include gable-roof designs, retractable roof houses, and Quonset growing or overwintering structures.
Gable-roof houses are gutter connected to provide large growing environments with a minimum shading from structural supports.
Retractable or open roof greenhouses are a relatively new greenhouse design that permits the roof of the greenhouse to be opened to almost completely vent the house.
The roof is opened either by retracting or folding the plastic cover or having the roof louver open for glass roofs.
This can reduce energy costs and since plants are grown under similar conditions to outdoors, propagated materials are better acclimatized to move to field or container production.
The quonset style of greenhouse is a very common plastic-covered hoop house used for propagation and over wintering rooted cuttings or grafted plants.
These are relatively inexpensive structures that offer a lot of flexibility for propagators.
They easily support ground bed, container, and bench top production.
Overwintering structures usually have minimum heat and are covered with white polyethylene.