I've jotted down a list of some of the supplies Deb and I have already purchased this year:
Drip irrigation system
irrigation timer
Limestone
Dr Earth
bacillus thuringiensis
organic fertilizer spikes(on sale)
yellow sticky traps
ladybugs (for gh)
azomite
cocoa coir
heat mat
plastic labels
useless metal labels
rootrainers seed starter
Today I decided to put a second layer of plastic over the greenhouse. It made a noticeable difference while I was there. The temperature started rising fast. We have some cold nights ahead of us in the 10 day forecast. It should drop into the mid 20s. I'm sure the 900 watt space heater could keep the frost away with a single layer of polyethylene, however, the temperature should stay about 50 at night for the young tender seedlings. We have a min/max thermometer. Last night the temperature got down to 45 degrees inside the greenhouse with an outside temperature of 31. I'll check it tomorrow to see what the double plastic does.