first time grow temperature problem

hi guys, im growing in a cuboard in the shed, the temperature is fine when the ligfht is on but when it goes of the temperature drops to around 16 degrees celcious, any ideas how i can get this up abit when the light is off.
low cost and low energy prefered.
cheers

Cermaic heaters can be set so they come on only when temp drops. They work well in a small space and are cheap.

a cupboard you say? what are the dimensions?

I have used in the past heat pads that go under the pots... If your in a small area they work really well. You can also adjust the temp settings on them.

Give it a look mate.

the dimensions are H60"xW31"xD17"
any ideas? the ceramic heaters run off like 2kw which is too high for me really.
thanks

Heating mats will probably be your best bet. Like previously mentioned you can find em for cheap and they are easy to use.

Or you can put a fish tank heater in a rubbermaid filled with water somewhat. then put your plants in another rubbermaid and set that rubbermaid in the tub with water in it.

That way the heat is kind of surrounding the plant and is easier to contain.