[Jeffrey Fouts]

If your growing in a cold space HPS could be beneficial to keep them girls warm. I run LED. A 1000 watt HPS will work in a 4×4 space, but there could be problems in the spring. Myself, I would stick with an LED and maybe a small ceramic heater. I don’t know what your budget is, but there are many lights out there. HLG is a pricy alternative, but highly recomended. Vipar spectra, has more budget friendly lights. I’m running two p1500s in my 2×4 and haven’t had any problems.

[jmystro]

HPS can be cheap to buy up front but buying $100’s of dollars worth of bulbs every few months get’s old. An oil-filled radiant heater is a good option as they don’t produce light for cold nights.

[simon-le-bong]

I recommend a good LED for your tent. Much more efficient overall, saving you money every month. If you’re in a part of the country where home cultivation isn’t legal, that HPS will show up on a FLIR camera like a giant hurricane in a satellite image. The driver for the LED light will add enough heat along with the light itself to keep your tent most likely at 21 Celsius or around there if the tent is closed. Assuming you’re in a cottage or flat and the ambient home temp is near 17 celsius in the coldest winter months. Cheers!

[backyard-boogie]

LED and a radiant heater, you might be able to get away with using the led and it’s driver as daytime heat source and have the heater on opposite timer settings to only kick on at night or lights out hours. You can probably find a used led at your local hydro shop or online that still has good life. Just seen on offer up a guy has 4 chilled led growcraft x6 for sale for $180 each. I believe they are normally in the $700 + range.