I just built a [harbor freight greenhouse](https://www.harborfreight.com/lawn-garden/gardening-garden-tools/greenhouses/6-ft-x-8-ft-greenhouse-47712.html) last spring, so this is my first chance to do get working on my plants before the frost clears here in Mid-May.
I’m most interested in tomatoes. I’m a tomato fiend. Anyway, I’m wondering if anyone on here has experience using an unheated greenhouse in zone 5b. When can I safely start my seeds? Recommendations seem to be all over the board.
by IAmTheLiquor23
8 Comments
It’s difficult to start tomato seeds without heat. Can you use a heat mat? (I have the 8X12 harbor freight gh in zone 8b)
I don’t put anything in my greenhouse until April/May and I am zone 4/5, it’s too expensive for me to heat.
I do start things indoors (in my living room) and move them into the greenhouse around that date.
The problem is that with out heat, the night time temps inside your GH will pretty much match outside temps. Even if you have full sun on cold days, which will really warm up the GH, night time will do them in
Why not start seeds indoors and move them out when its warmer?
My small greenhouse is zone 5b. My local university extension office says tomato seeds need heat to germinate (~85F). Start them indoors in February. Start heating your greenhouse in May, and move the plants outside. Monitor the interior temperature, maintaining about 72+/- daytime and 62 +/- nighttime temperatures. You will be harvesting before your neighbors.
I have a small unheated greenhouse in 5b and I use it to start cold hardy plants in spring. The temperature fluctuates too much for things like tomatoes but it’s a great environment for cold hardy flowers like anenomes, ranunculus and bells of Ireland, or cold veg like spinach, kale and peas.
I had that greenhouse and it only survived until Buffalo winter 🙁
Definitely will need to heat it if you want anything started super early. Insulating the interior walls helps a ton to conserve on bills.