Hydroponic Light Timers, Meters & Controllers

Start with a timer

Of everything on this page, a timer is the one piece of equipment no indoor grow should be without. Plants respond to consistent day length, and flowering in particular depends on an uninterrupted dark period. Switching lights by hand works right up until the evening you forget, and a single interrupted dark cycle can stress a flowering plant badly.

A basic plug-in timer handles a single fixture. Mechanical dial timers are the cheapest and are hard to break, though they switch in 15-minute increments. Digital timers give you precise start and stop times, multiple programs a day, and usually keep their settings through a power cut.

When you need a heavy-duty timer

A standard plug-in timer is rated for one light. Run several and you exceed what the switch inside can carry — which is a genuine fire risk, not just an inconvenience. Multi-outlet timer boards and contactor boxes exist for exactly this: the timer switches a relay, and the relay carries the load.

If you are running more than one or two fixtures, this is the point to move up rather than daisy-chaining plug-in timers.

PAR meters — what light is actually reaching the plant

Manufacturer coverage claims are measured under ideal conditions. A PAR meter measures the light landing on your canopy, at your hanging height, in your tent, with your walls. It is the only way to know whether a fixture is too high, too low, or leaving corners dark — and it makes a real difference when you are comparing two lights or setting up a new space.

The extendable wands sold alongside them let you take readings across the canopy without leaning over your plants.

Controllers and dimmers

A controller sits between your fixtures and the wall, letting you dim several lights together, ramp them at sunrise and sunset, or adjust output to conditions. Some are brand-specific — Hortivision, Digi-Lumen and Hi-Par each make their own — while multi-zone units run several fixtures independently. Worth it once you are running more than one light; unnecessary for a single fixture with a dimming knob on it. See the full LED grow light range for what they control.