What can you grow in a greenhouse? That depends on your climate, your intent, and your greenhouse setup. The National Orchid Garden in Singapore has an air conditioned greenhouse for mountain orchids and other cool weather orchids that could not survive in their tropical climate. While in in southern Florida, "screen rooms" are more common than greenhouses to protect the plants from the hot sun, insects and birds.

Here in the Northwest, typically greenhouses are used to even out temperatures throughout the year, and primarily, to protect plants from the harsh winter freezes.

The number of independent sections, the size and the heating and environmental controls installed within the structure ultimately affects the conditions available for growing a variety of plants.

vines and fruit
If you wish to grow vines and fruit such as nectarines and figs, a lean-to structure against a garden wall is recommended for the extra warmth it provides. Maximum airflow through the building, combined with the good sloping roof, effectively reduces the chance of fungal disease.

vegetables
If you wish to grow vegetables, like zuchinni, cucumbers, carrots, lettuce, and tomatoes (fruit), a Value-hut or standard Glasshut greenhouse are recommended for the growing space and options you can equip your greenhouse with. Consider heating solutions for early harsh winters to protect susceptible plants like tomatoes, cucumbers, etc.

flowers
If you wish to grow assorted flowers, a Gropod, Value-hut or standard Glasshut greenhouse are recommended for the location, position and flexibility they provide in accomadating your plant needs. Consider plasting sheeting (thermal blankets) or heating solutions for early harsh winters to protect susceptible flowers like geranniums, etc..