The pitch for a greenhouse is usually "grow year round." That's not honest for the BC interior without heating, so here's what actually happens.
What you gain in spring
Soil temperature, not air temperature, is what holds spring back. Under cover, soil warms two to four weeks ahead of an open bed — earlier in a sunny spring, later in a wet one.
Practically that means starting hardy crops in March instead of mid-April, and having your own transplants ready at the moment the outdoor beds are workable, rather than buying them.
What you gain in fall
This end is bigger, and it's the one people underestimate. The first frost typically ends an outdoor garden while the plants are still healthy and producing. Under cover you carry on — often three to five weeks longer, sometimes more.
For tomatoes and peppers in particular, that's the difference between ripening the last trusses and composting them green.
What you don't get
An unheated greenhouse will not grow tomatoes in January anywhere in this region. Once daylight drops below roughly ten hours, most fruiting crops stop regardless of temperature.
What does work through winter: hardy greens, spinach, kale, mâche, and overwintering alliums. Cold-tolerant, low-light-tolerant crops that would die outdoors but sit quite happily under cover.
Regional differences worth knowing
- Kelowna and the south — long season already; a greenhouse is mostly about heat control and an early start
- Vernon, Armstrong, Enderby — the sweet spot, where a few weeks at each end genuinely transforms what you can grow
- Salmon Arm and Sicamous — moisture and disease pressure are the real problem, and cover solves that more than season length does
- Revelstoke and the mountains — the shortest season, and where a greenhouse makes some crops possible rather than just earlier
Getting the most from it
Roll-up sides matter more than people expect. Ventilation on a hot afternoon is what stops a greenhouse cooking its own crop, and being able to close it down before a cold night is what buys you those extra autumn weeks. Both our models have them, hand-cranked.
See both models, or ask us what's realistic where you are.
