LED lighting basics for edible plants

You don't need to understand PPFD or photon flux density to pick the right light. You need two numbers: the right wattage for your tent, and the right hanging height for your plant's stage. Get both roughly right and you'll outperform someone with a fancier fixture they don't understand.

The wattage cheat sheet

These ranges assume a modern full-spectrum LED at 2.5 µmol/J or better. Older blurple LEDs and cheap 'Amazon specials' often advertise inflated wattages — always check the actual draw at the wall, not the marketing number on the box.

Hanging height by stage

• Seedling (week 1–2): 50–60 cm above the soil, dimmed to 50% if your fixture allows.
• Vegetative (week 3–6): 40–50 cm above the canopy, dimmed to 70%.
• Fruiting (week 6 onward, tomatoes & peppers): 30–40 cm above the canopy at full power.

How to read the plant

Plants are surprisingly clear about whether the light is right — you just need to know what to look for.

• Top leaves curling down and away (a 'taco' shape): too close, raise 10 cm.
• Top leaves bleached white or yellow: way too close, raise 15 cm and dim if possible.
• Plant stretches tall, big gaps between branches: too far away, lower 10 cm.
• Leaves flat, even green, pointing slightly up at the light: perfect — leave it alone.