GAHT Greenhouse

[Britesea]

You could try something like the old style hot beds- put a layer of hot manure or compost under a layer of sand on the floor of the greenhouse-- the heat from the decomposing manure/compost would add a bit of heat to the greenhouse?

 

[cabinguy]

It would if you could keep the water out of it so it wouldn't become a swimming pool. Good drain tile system with sump pumps should work well.

Agreed water could be the issue
However it would extend the greenhouse season both early and late.
Checkout the Walipini Greenhouse designs

 

[Mini Horses]

You could always put the compost/sand on the dirt floor...then remove & replace each year -- or a tall ceiling

I read where a guy puta raised walk in the middle of his, with lifting panels & kept earthworms in that area, year round. Additionally, at each end, he had a small coop for a few chickens...roost raised, portable fence divider for balance of house. Between the composting worms & chicken heat, he was pretty good MOST of the year for cold crops in there. Another innovative method.