Countertop HarvestBy the Countertop Harvest team · Last updated
How many hours of sun do herbs need?
Penn State Extension says most herbs need 6 hours of direct sunlight, from a window with a southern exposure. Iowa State Extension goes further: most herbs grown indoors need around eight hours of direct light. A south-facing window is best, and a bright east or west window can work. Some herbs tolerate less. Penn State lists chives, cilantro and lemon balm as able to manage on 2–6 hours.
Signs your herbs need more light
- Thin, spindly stems that lean toward the window
- Smaller leaves and weaker aroma (Penn State)
- Pale or yellowing foliage and leaf drop (Iowa State)
Rotate windowsill pots often so each side gets light (Penn State).
Using a grow light: hours and distance
| Question | Extension guidance |
|---|---|
| How many hours? | 12–16 hours a day on a timer (Iowa State); 14–16 hours under fluorescent tubes (Penn State). Plants still need a dark period. |
| How close? | Fluorescent fixtures about 6–12 inches from the leaves; LEDs often 12–24 inches depending on strength (Iowa State). Follow your light's instructions. |
| Seedlings? | Closer: no more than 4 inches above seedlings, and 2 inches is ideal (UMN Extension). |
| What type? | Full-spectrum grow lights in high-output fixtures (Iowa State). |
Too much light?
Indoors this is rare, but Iowa State lists leaf scorch, bleached leaves and extremely compact growth as signs to move a light further away.
Choosing a setup
For pots you already own, an under-cabinet bar or clip-on LED is the simplest fix. See grow lights for winter herbs and grow lights under $50. If you'd like light and watering handled together, a smart garden or hydroponic kit has a built-in light. Track your daily light routine with our free 30-day herb planner.
Ready to buy? See the best grow light for indoor herbs.
Sources
- Penn State Extension: growing herbs indoors
- Iowa State Extension: growing herbs indoors
- Iowa State Extension: providing more light for herbs
- Iowa State Extension: setting up supplemental lights
- UMN Extension: starting seeds indoors
Frequently asked questions
How many hours of light do indoor herbs need?
Most need about 6 hours of direct sun (Penn State Extension). Iowa State notes most do best with eight or more hours indoors.
How long should a grow light be on for herbs?
12 to 16 hours a day on a timer, per Iowa State Extension. Don't leave it on continuously.
How far should a grow light be from herbs?
About 6 to 12 inches for fluorescent fixtures and often 12 to 24 inches for LEDs, depending on strength. Follow the maker's instructions.
Which herbs tolerate low light?
Penn State Extension lists chives, cilantro and lemon balm as tolerating 2 to 6 hours of direct sun.