Adding a greenhouse to a Minneapolis-area garden can certainly extend the gardening season a little bit on each end of the bitter cold Minnesota winter. While most of the state falls in USDA climate zone 4a, there are patches that are classified as USDA zone 2b: this means that Minnesota winters can hit consistent lows of 25°F to -45°F. So while the short growing season and low winter temperatures alone can certainly make a greenhouse look attractive, there are other factors to consider.
First and foremost, it’s useful to think about the space available in the garden. A greenhouse large enough to walk around in can take up a significant chunk of real estate, and it should be situated with good sun exposure, and far enough away from potential hazards like falling tree branches as possible.
If space is a concern, a smaller microclimate solution may be in order, such as a cold frame or a wall or lean-to greenhouse. These simple mini-greenhouse designs can shelter more tender plants in winter, and be used to propagate seedlings in early spring.
How Does Your Garden Grow?
Secondly, it is useful to consider how you use your garden space, as this will also dictate the type of infrastructure you will get the best use out of.
An unheated greenhouse can be a space for hardcore vegetable seeding in spring, winter storage of plants that are tender by a zone or two, or as a cozy and warm sitting room in spring, summer and autumn, sheltered from the wind and rain.
A heated greenhouse, on the other hand, can be an “orangerie” for growing very tender plants, like citrus trees. It can be a place for all-season gardening projects. This of course entails a significant investment in making sure it is insulated, sealed, temperature-regulated, and of course consistently-heated, so it is perhaps only an option for the most devoted of winter gardeners.
The best results will come if you consult with a landscaper about integrating a greenhouse into your garden design. It is a significant investment that requires upkeep and use to maintain it’s value in a landscape.
However, a durable and well-suited greenhouse can add value to a property, and allow for a greater diversity of plants to be cultivated at home, never mind providing a tropical-feeling enclave for the enjoyment of plants and people alike.