Winters are long and cold in Canada, and a gardener can get antsy as the months go by. What you need is a greenhouse—or a sunroom, conservatory or solarium—to call your own: somewhere you can overwinter plants, start new seedlings, even produce mid-winter vegetables.
Still, having your own personal crystal palace can cost about $25,000, easily as much as adding an extension to your house. After all, you need a solid foundation (dug down below frost level, as glass won't tolerate bending or shifting), excellent insulation (usually double-glazed, tempered glass), a heating system, electrical and water outlets, and a ventilation system. Except for the most talented of do-it-yourselfers, you'll also have to hire a contractor, and possibly an architect.
In truth, a year-round, heated greenhouse with seemingly limitless space probably is beyond many budgets. But you can have a smaller structure at an affordable price. If you want year-round growing, there are permanent greenhouses that won't cost an arm and a leg. You can cut costs further if you opt for a non-winterized structure. Some of the greenhouses described below cost less because they are temporary, install-it-yourself affairs.
Here are a few points to keep in mind when planning your greenhouse. Even if you only want a sunny, warm place for a small houseplant collection, both the collection and the plants will grow. Figure out how much space you'll require, then add another third.
Greenhouse structures are covered by municipal bylaws only if they are permanent. Always check with your local building permit department early in the planning process; there may be limitations on where you can place your greenhouse and even the type of covering used.
And don't be tempted to save money by using inappropriate materials. Non-tempered glass is fragile and cracks easily; plain polycarbonate panels aren't treated to prevent condensation; and ordinary plastic film isn't UV-resistant and rarely lasts more than a few months when exposed to full sun. Unless you intend to grow foliage plants only, avoid heat-mirror or tinted glass—often recommended for sunrooms to reduce heat loss—as it doesn't allow enough light in for your plants. A compromise is low-emission glass, which lets in less light than double-glazed, tempered glass, but has better insulating properties—and provides enough light for flowering plants.