Poly tunnel heating for bedding plants
I've got a bit of a problem I was given loads of old seeds by an elderly relative. I planted them all as I assumed only a handful would come up, but I've ended up with over 3000 bedding plants, and i've got about 2000 more than will need pricking out. My 10x12' greenhouse is crammed, so I've built a temporary polytunnel out of a couple of old tent frames and a plastic sheet i got on eBay, it's 9x30' roughly . Last night it went out to check the temperature in there at about 11pm and it was just above freezing, I quickly went and got a couple of 1KW electric heaters and put them in there but they barley made a difference but going forward i think i will need to heat it otherwise i'm going to loose the lot. I was thinking of a 5KW diesel heater from a campervan, runs on red diesel which is quite cheep, but is 5KW going to be enough? or will i need 2 or even 3? Incidently my greenhouse has 3 massive water tanks under the bench and a large heat sink under the ground so heating is not really a problem it only droped to 6°C last night, but the poly tunnel is a bit of an issue.