How Far Should Grow Lights Be From Plants?

It's one of the most-asked questions in indoor growing — and for good reason: grow-light distance is the difference between compact, thriving plants and stretched, bleached, or stalled ones. Too far and your plants reach desperately for light; too close and you scorch them. Here's how to get it right.

"Plants don't eat fertilizer. They eat light." — Andrew Woodward

Why distance matters so much

Light intensity drops off fast as it travels — move a light twice as far away and the energy reaching your plant falls dramatically. That's why two growers with the same light get wildly different results: one has it dialed in, the other doesn't. Distance is the dial.

The two failure modes

• Too far away: plants stretch toward the light, growing tall, leggy, and weak with big gaps between leaves. This is the most common beginner mistake.
• Too close: leaves bleach, curl, or develop burnt tips — light "burn" from too much intensity (and sometimes heat).

General distance guidelines by stage

Exact numbers depend on your light's power, but the principle holds across every setup:

• Seedlings & clones: the most sensitive — keep light farther and gentler.
• Vegetative growth: bring it closer as plants toughen up and demand more energy.
• Flowering/fruiting: highest light demand — closest, as long as you watch for stress.

The only way to actually know: measure

Guidelines are a starting point, but plants don't read charts — they respond to intensity at the canopy. The professional approach is to measure PAR/PPFD at plant height and adjust distance until you hit the right range for your stage. Then confirm with the plant itself.

Let your plants tell you

Your canopy is the best meter you own:

• Stretching, reaching, pale lower growth? Light is too far — lower it.
• Bleaching, curling, crispy tips on top leaves? Too close — raise it.
• Compact, deep-green, tight growth? You've found the sweet spot.

The bottom line

There's no single magic number — there's a range you find by measuring and reading your plants. Once you understand how intensity changes with distance, you stop guessing and start growing with intention. The best growers aren't lucky. They're observant.

Want to master PAR, PPFD, DLI, and dialing in light for any crop? Mastering Light is Module 3 of Aero-Gro Academy — it turns lighting from guesswork into a skill.