Lighting Configuration: Ballasts, Reflectors, LEDs & Timers

August 25, 2025 Tom H

Lighting Configuration: Ballasts, Reflectors, LEDs & Timers

A grow light is more than just a bulb. A full system usually includes a lamp or LED fixture, a ballast or driver, a reflector, and a timer or controller. Here’s how to put it all together and keep it running safely.

What’s in a Grow Light System?

Grow Lamp / LED Fixture: HID lamps emit light directly, while LEDs use diodes arranged across bars or boards.
Ballast / Driver: Regulates power to the lamp. HIDs need a ballast (magnetic or digital). LEDs come with in-built drivers, so no ballast required.
Reflector: Bounces and spreads HID light down onto the canopy. LEDs use angled diodes and bar layouts to give natural spread — no reflector needed.
Timer / Controller: Automates on/off cycles. Many modern LEDs plug straight into digital controllers or app systems.

Step-by-Step: Setting Up

Hang your reflector (HID) or LED fixture using rope ratchets or hangers.
For HID: firmly screw the lamp into the lamp holder. For LED: just secure and plug in.
HID only: connect the reflector cable to your ballast.
Plug your ballast (HID) or driver (LED) into a timer or controller.
Set your light cycle (e.g. 18 hours on / 6 off for veg, 12/12 for flower).
Plug the timer into the mains — and you’re good to go.

Timers & Contactors

Always use a heavy-duty timer or contactor for HID lights — they draw big start-up currents that can burn out cheap timers. LEDs are far more efficient and often safe on a standard digital timer or smart plug, but check the wattage rating first.

Ballasts vs LED Drivers

Magnetic ballasts are now a thing of the past, digital ballasts are lighter, quieter, and run lamps 3–4% more efficiently, often with dimming options. LED fixtures don’t need a ballast at all — they come with a matched driver that regulates power cleanly and efficiently.

Reflectors & Spread

HID lamps lose nearly half their output without a reflector, so choose carefully: open-ended, air-cooled, or adjustable models all affect spread. LEDs don’t need a reflector — multiple light bars or precision designed optics give even distribution straight from the fixture. Just hang level, and you’re sorted.

Replacing Equipment

HID Lamps: Replace every 6–12 months. Output degrades over time, cutting yield.
Reflectors: Replace roughly every 6 months if using HID. Dust and tarnish reduce reflectivity.
LED Fixtures: No bulb swaps needed. Clean bars and drivers, check dimming and controller functions annually. Expect years of consistent output.

Quick Tip: LEDs are plug-and-play compared to HID. No ballast, no reflector, and lower heat output — but still check tent temps. HID still delivers raw power at lower upfront cost, but running costs are higher.

Final Thoughts

Whether you run HID or upgrade to LED, the setup basics remain: hang securely, automate with a timer, and keep reflectors, lamps, or bars clean. Stay on top of replacements (or checks for LEDs), and your lighting system will deliver consistent growth cycle after cycle.

This blog is part of our How to Grow Indoor Plants – Your Complete Guide series, designed to tell you everything you need to successfully grow indoors.