Clair, how cold is it there? More information on your grow house would be appreciated. I grow all of my seedlings here in northwestern Arkansas, USDA Hardiness Zone 6, Sunset Zone 35, in a low tunnel I made of PVC pipe and 6 mil greenhouse plastic. It’s unheated. I do take my seedlings indoors at night to prevent them from freezing (Though this has not been needed as much lately, as it’s been very mild weather.), but during the day, even if it’s below freezing all day, it maintains at least 50 F. With no wind inside, that’s perfectly fine for the cool weather seedlings. I suspect in the UK you guys rarely have below freezing spells for weeks like we do occasionally, so you’d probably be fine. I vent it when we hit 40 F and it’s sunny, as it will quickly hit 100 F inside if allowed much higher. It averages 50-70 F on the coldest days at this time of year. You may wait until it gets warmer, as I am, to sow warm weather crops like tomatoes or peppers. The normal time here is mid March, which is perfect for transplanting in mid May, our average last frost date.
I suspect the grow house would be fine, but more information on it would be appreciated! Is it plastic, or fabric? Is it enclosed? etc.
