Yep , make a good thick layer of horse crap and straw mix , covered by soil , preferably sterilized as other wise you get a fantastic crop of weeds . Then place the cold frame on top .
You can plant directly into this soil , or in trays or pots as normal .
Lift the lid to control the temp .
A 2 foot layer of manure will last about 3 weeks and gradually cool off till the temp outside is correct for transplanting .
Care needs to be taken at first as the heap may generate enough heat to cook the seeds or plants placed in the frame .
Melons grow well this way .
At the end of the year the soil and manure can be put on the veg plot .
Harry Dobson knew what he was doing , lovely bloke too .