If you’re wondering how long to run grow lights in winter, the good news is: you don’t need complicated charts. Most indoor plants do best with a consistent winter grow light schedule—the same hours every day—then small adjustments.
Why winter requires a different plan
In winter, your plant experiences:
• Shorter days (fewer total daylight hours)
• Lower sun angle (light doesn’t penetrate as deeply)
• More cloudy days (lower intensity even when it “looks bright”)
• Indoor placement (further from windows, filtered through glass)
So your goal isn’t “maximum light forever.” Your goal is a stable, repeatable grow light duration that mimics a dependable day.
Consistency is what prevents that classic winter problem: “I ran it 4 hours today, forgot tomorrow, then did 12 hours the next day.”
STEP 1：The Quick Rule (Start Here)
For most grow lights for indoor plants in winter:
• Bright window + small boost: 6–8 grow light hours
• Some window light, but weak: 8–12 grow light hours
• Low-light room (mostly relying on lights): 12–14 grow light hours
• Seedlings / high growth: 14–16 grow light hours (avoid going over 16 long-term)
If you’re unsure, start at 10–12 grow light hours per day.
Step 2: Choose a “daytime window” (timing matters)
A reliable winter grow light schedule is usually best when it happens during your normal day, for example:
• 7:00 AM – 5:00 PM (10 hours)
• 8:00 AM – 8:00 PM (12 hours)
• 9:00 AM – 11:00 PM (14 hours)
Try not to run your grow light hours entirely overnight if you can avoid it. You don’t need to perfectly match sunrise, but keeping it aligned with daytime generally supports a more natural rhythm.
Don’t Change It Too Fast
Set your grow light duration and leave it for 7–10 days. Plants need time to respond.
Then increase grow light duration by 1–2 hours if:
• the plant is stretching (leggy growth)
• new leaves look smaller
• leaves lean strongly toward the light
Decrease grow light duration by 1–2 hours if:
• leaves look pale/washed out (after checking watering)
• leaves curl or look stressed
Tip: If growth is still weak at 12–14 hours, the issue may be grow light distance or coverage—not time.
Make It Automatic (So You Don’t Forget)
The best winter grow light schedule is the one you can keep.
Use a plant grow light timer to lock in your grow light hours.
If you’re using Glowrium G4、G5 、G6、G7、G8, you can also set schedules in the grow light app for different plant zones—so your routine stays consistent even when life gets busy.
And if you’re not sure what your plant actually needs, our updated app includes a Auto Timer & Sunrise/Sunset Mode. Once you bind your plant to a compatible light, the app can recommend a target grow light duration—and you can choose from multiple timer styles. It’s an easy way to stay consistent without overthinking the schedule.
Winter Cheat Sheet (Save This)
• Window boost: 6–8 grow light hours
• Weak window light: 8–12 grow light hours
• Mostly lights: 12–14 grow light hours
• Seedlings: 14–16 grow light hours
• Change slowly: adjust grow light duration by 1–2 hours after 7–10 days
• Automate with a plant grow light timer / grow light app
FAQ
Can I run grow lights 24 hours a day in winter?
Not recommended for most grow lights for indoor plants. Many plants do better with a daily dark period. A safer range is usually 12–14 hours/day, and 14–16 hours/day for seedlings.
What if I’m already doing 12 hours and my plant is still leggy?
Legginess can come from weak intensity (distance/coverage), not just grow light duration. Before adding hours, make sure the LED grow light is positioned so the plant is actually receiving strong light across its canopy.
Is window light enough in winter without a grow light?
Sometimes, but often not—especially for indoor plants placed away from the glass, in shaded windows, or in cloudy climates. If you’re wondering, start with a small boost: 6–8 hours/day added as grow light for houseplants.
What’s the best “on” time for winter?
Any consistent daytime window works. A common winter grow light schedule is roughly 8 AM–8 PM (12 hours). Choose what fits your life and stick with it.
