Heat

[BDG]

Thing is in the UK, little point of lots of heat in the winter - you just want enough to stop things from freezing - as we do not really get the light for a lot of active plant growth. You can make it as warm as you like and stuff still wont grow.

The reason for heat is to stop stuff like pak choi, mustard and other winter leaves dying off and to give you a bit of heat early on in the season to help with small tomato plants - you do not need a lot.