Ballasts are necessary for grow lights to operate. Grow Light Ballasts power the high intensity grow bulbs and lamps via 120 volt or 240 volt power. You connect a ballast to a reflector or socket by the cord that comes off the reflector or socket you screw your grow light into. Some ballasts power specific bulbs such as HPS or MH, and others known as "Switchable" can power both HPS and MH bulbs. Digital ballasts are also often dimmable meaning the wattage can be dimmed down e.g., 1000w ballast can be dimmed to 600 and 400w. To learn more about HID lighting read our buyer's guide. HID Lighting Buyer's Guide.


Grow light ballasts power high intensity grow bulbs and lamps by regulating the voltage a high-intensity discharge (HID) light or compact fluorescent light receives. Some ballasts power specific bulb types while others are "Switchable" and can power both HPS and MH bulbs. There are three types of ballasts, electronic, digital, and magnetic, typically available in various wattages from 315w to 1000w.

Digital ballasts

Digital ballasts are the latest technology that uses microprocessors to monitor and regulate the voltage and are often dimmable.

Double Ended ballasts

Double-Ended ballasts are specifically made to power double-ended fixtures safely.

Magnetic ballasts

Magnetic ballasts are an older technology and use an electromagnetic system for controlling voltage. They are typically cheaper than the other ballast technologies.

T5 Fluorescent ballasts

Fluorescent ballasts are made specifically to power your fluorescent lights such as the longer T5 bulbs frequently used for propagation of many plants in one small space.