LED Light for Microgreens: How Much, How Close, and How Many Hours You Need
The three settings that matter
| Setting | Practical range | What happens if you get it wrong |
|---|---|---|
| Photoperiod (hours on) | 12–16 h/day | < 10 h: slower, spindly stems. > 18 h: energy waste + sometimes pale leaves. |
| Distance from canopy | 15–30 cm (6–12 in) below the fixture | Too far: stretching. Too close (<10 cm): leaf scorch on sensitive crops. |
| Spectrum | Full-spectrum white (5000–6500 K) works great | Cheap red/blue: works, but uneven and hard to judge visually; not worth it for beginners. |
How much light do you actually need?
Microgreens tolerate much lower light than lettuce or fruiting crops. A rule of thumb for good growth:
- One standard 10–20 W clip-on or panel light at ~20 cm above a single 1020 tray is enough in winter when the windowsill falls short.
- A ~$20 clip LED covers roughly one tray well; two trays want either a bigger panel (30–60 W) or two clips offset on opposite corners.
- Don't chase "professional" numbers: if your microgreens are compact, deep-colored and not stretching — you're fine.
Common setups and what they cover
| Setup | Cost (rough) | Coverage | Notes |
|---|---|---|---|
| $15–25 clip LED + timer | ~$20 | 1× 1020 tray | The beginner standard. Timer = set-and-forget. |
| 30–40 W panel with hanging bar | ~$40–70 | 2–4 trays in a rack row | Good for a corner shelf rig. |
| 60 W+ full-spectrum panel | ~$80–150 | a full 2×2 tray grid or small rack | Where you go if you scale to selling. |
The winter windowsill trap
In winter, a north-facing window might give 2–4 h of real sun — microgreens respond by stretching (long pale stems) and lodging. Two fixes: add the clip LED on top for the remaining hours, or move the rack to a south/east window + supplement. A windowsill-only winter grow usually fails; plan for the light.
Sources
- Cornell Small Farms Program — microgreen production guidance (light requirements).
- Utah State University Extension — microgreens guide (photoperiod ranges).
- Retail LED specs (clip/panel wattage and coverage), checked 01.10.2026.