Back in 2008 I was treated to a Vitopod electric propagator. My conclusion after 8 years is that it is one of the best investments a serious gardener can make. It’s not just useful for propagating, it’s great for over-wintering tender plants as well.
Vitopod Electric Heated Propagator – Large, Double Height Space for 55 Pots or 12 Seed Trays – Available from Harrod Horticulture
The Vitopod is available in two base sizes, the large (double) one being roughly 2 x 4 feet and the single half that size. I strongly suggest you go for the double if you can. Like a greenhouse, whatever size you have you could always do with a little more room.
The Vitopod base is a solid, heavy plastic tray about 2″ deep which contains the heating elements. The base draws 100 watts so it’s powerful as these things go, useful if the weather springs a surprise and temperatures plummet.
The temperature is controlled by a separate thermostat with one degree accuracy. It’s actually designed for aquariums and terrariums where people keep reptiles which require close temperature control.
This means your plants are exactly at the right temperature and it reduces energy usage.