Grow Light CheckPlant grow-light guide
How much grow light does Indoor herbs need?
Most culinary herbs require stronger light than tolerant houseplants to remain compact and productive indoors. A practical starting target is 200–500 µmol/m²/s at the leaves for 12–16 hours per day, followed by gradual adjustment based on the plant’s response.
Written and reviewed by Grow Light Check · Updated
Indoor herbs light targets at a glance
| Plant | Common culinary herbs |
|---|---|
| Starting PPFD | 200–500 µmol/m²/s at the leaves |
| Photoperiod | 12–16 hours with a consistent dark period |
| Starting setup | Use a bar or panel that evenly covers the full tray and keep the growing tips within one height range. |
Choose distance from output, not watts alone
A narrow bulb, a diffuse clamp lamp, and a long bar can all draw the same electrical power while delivering very different light at the leaves. Use published PPFD at a stated distance when available. Otherwise account for PPF or PPE, beam shape, coverage and distance.
Let the plant confirm the setup
Possible under-lighting
Thin stems, long spaces between leaves, pale growth, or weak aroma and production.
Possible over-lighting
Bleached upper leaves, heat stress, or rapid drying directly beneath the fixture.
Change intensity or distance gradually and evaluate healthy new growth over time. Water, roots, nutrition, temperature and pests can produce similar symptoms.
Source and limitations
The target is a broad household starting range, not a species maximum or a guarantee of flowering. Background plant-care guidance was reviewed against University of Minnesota Extension; the numeric range is Grow Light Check’s practical interpretation for broad-white electric lighting.
Use the result as a starting point
A listed wattage is electricity use, not plant-level brightness. Reflectors, lenses, fixture dimensions, spectrum, barriers, and the illuminated area all affect the result. Manufacturer PPFD maps or a reading from a cosine-corrected quantum meter are stronger evidence than wattage alone.
Sources and review basis
Sources support the background guidance; numeric ranges and product-fit conclusions are Grow Light Check’s bounded interpretation.