fireproofing my box/closet

I literally have a grow box. It's cardboard painted flat white with 4x cfl bulbs, temps cruising at 79 on a hot day.

Anyways, it's cardboard, so it's pretty fire friendly and i'm worried about it. I'm on a limited budget but will need to expand my box sooner rather than later.

How about sheetrock? I know it's mostly fire-proof, and if something happened in the closet, It would be contained.

Is insulation foam fireproof? I'm willing to bet it is, plust it's lighter and cheaper than sheetrock.

Any advice?

Most types of insulation are fire resistant, especially Rockwool. However, most fires are going to stem from an electrical malfunction or an overload of charge maxing out above what your outlet/ballast/power strip can handle. If you're careful and take time setting up your electrical system you shouldn't have to worry too much about a random fire sprouting up and burning your house down.

Okay electrical work then. I'll also put some rock quarry tile on the floor (2x2 is $.97 after tax)