No, you need a ballast at the very least. Ballasts control the electrical current running to the bulb. HPS bulbs are not able to control the current running into them like incandescent can. Incandescent bulbs use what's called a filament that acts as a natural resistor to limit current throughput. HPS bulbs do not have filaments, and will therefore draw current at an unlimited rate until it is destroyed (I don't know how long it will take for a 250watt HPS bulb, but it definitely is NOT long enough to grow cannabis). I would guess it will either burn out or explode within a day without a ballast.