could use some help is it possible to put a space heater in my grow box??????????

i am building a grow box that is 5 foot long 3 feet wide and 5 feet high. the grow box is going in my shed but the problem is where i live its really cold temperatures in the 20s some times. I was thinking if possible could i put a very small space heater i have seen very cheap ones for 12 bucks and put it right in my grow box i am however going to buy a very good quality thermostat that is for growing so it stays at the right temperature. the grow box is going to be insulated. My other option is to insulate the whole shed and heat the whole shed but i looked into this and its very expensive. i mean i will if i have to life goes on. i guess the only thing im worried about is that the heater will dry out the plants if i heat it and keep it more humid with maybe a humidifier or something would this do the trick?any help would be awesome thanks guys

do you mean these small ceramic heaters with the fan??? dude these are a NO NO! they are not meant to be left unattended, if the fan breaks they BURN! remember the horrible swiss tunnel fire that killed like 100 skiers? it was caused by one of those placed in the cockpit of the train! the space is good you can place a small heater in there just dont go cheap with such an item, you could get electric heaters that are quite safe. you can also start with insulating the grow box

well is there any other way of heating the box the right way like without drying out the plants has anyone else had to do this?

Oil filled radiant heaters are probably the safest - though also the biggest.
I've got a small ceramic type with a thermostat. I keep it at a pretty low setting to keep my cabinet about 70f or so - I'm not going fo tropical.
I've got it hanging up with my circulation fan, so overheating shouldn't be a problem.

I have always had heaters in my grow room it's just good insurance where I live. Just buy a good small one with a good thermostat built in. The hard part is setting it right, the plants will take low temps but yo-yoing temps is not good. Make sure you have a small fan going all the time to move the air.

I have had great success with a small forced air electric thermostaticly controlled space heater I bought at Wallmart for $32.00 I have it hung from the ceiling and it works great. Pix of it are posted here on my grow journal .https://www.rollitup.org/grow-journals/393424-harrys-first-grow-looking-forward.html I maintain a 74.5 degree daytime temp with a steady 69 degrees at night in my indoor garden.

I also have a small $30 wally mart heater with thermostat set at 60F.. Keeps my grow at 62 F at night. I usually just check the wiring out each time I'm in there. Feel the plug to make sure it is'nt warm and always keep objects 3feet away from the heater on all sides and you should be ok. Safety first.

ive tried ceramic heaters but theyre no goid because the temp was always going up and down and the heater would turn on every few minutes. to keep a steady temp youd need a radiator heater or whatever its called.