Light is the fuel of indoor growing — but more is not always better. The right duration (photoperiod) varies by plant, and even by the growth stage of the same plant. This guide gives a practical light schedule for the most popular crops grown in GrowlyBox.
What is a photoperiod?
A photoperiod is the number of uninterrupted light hours a plant receives in 24 hours. Plants photosynthesise in light and run respiration and cell repair in darkness. Both sides of the schedule matter: enough light and enough darkness.
Plant-by-plant light schedule
- Microgreens: 12–16 hours — fast cycle, tolerant of intense light
- Lettuce and leafy greens: 12–14 hours — more can cause bitterness and early bolting
- Spinach and chard: 12–14 hours — they prefer cool, moderate light
- Basil and kitchen herbs: 14–16 hours — generous light means generous aroma
- Tomatoes: 16–18 hours as seedlings, 14–16 after flowering and fruiting
- Peppers: 16–18 hours as seedlings, 14–16 during fruiting
- Strawberries: 12–14 hours — varies by variety; everbearing types are day-neutral
Intensity matters as much as duration
GrowlyBox's 75W full-spectrum panel covers every stage from sprout to harvest with 144 Samsung 281B+ LEDs. Seedlings prefer gentler light, so profiles run the panel at reduced power early on. If you see curling or bleached leaves, the intensity is too high — reduce power before you reduce hours.
Why darkness is non-negotiable
Uninterrupted darkness is as critical to a plant's hormone balance as light. Even a lamp left on in the room overnight can confuse the flowering of some plants. GrowlyBox's fully isolated door solves this at the root: room light never leaks in while the cabinet is dark, and not a single photon spills into your room while the light is on. The photoperiod runs completely independent of your living space.
Light automation in GrowlyBox
Choose a plant profile in the app and the schedule sets itself: the panel switches on at the same time every day, and the duration updates gradually as the stage changes. You can shift the cycle to fit your routine — set the light to run 07:00 to 21:00 and your plant is lit whenever you check on it in the evening.
3 practical tips
- Do not change the light cycle more than once a week; plants love consistency
- Yellowing lower leaves plus a stretching stem signal too little light; curling tips signal too much
- Worried about electricity? The 75W panel uses about 1.2 kWh over 16 hours a day — see our power consumption article for the full math
Get the trio right — correct schedule, correct intensity, uninterrupted darkness — and your plants will grow on their most productive cycle, whatever the season outside.