Find out how long you want to put houseplants under full spectrum, artificial lighting each day. This video tells you the range of hours you want to have the lights on and off per day for low-light, medium-light, high-light plants and seedlings. It’s a good idea to keep them on a lighting schedule. Time of year will also affect the length of time you keep the full-spectrum lighting on your houseplants.
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Today, I’m going to talk about how long to put plants under full-spectrum artificial lighting. If you’ve just bought a system like this one from Gardener’s Supply, you might be wondering how many hours per day to leave it on. The same applies if you’re using bulbs in fixtures—there are many ways to provide full-spectrum light, but how long should the lights stay on?
Here are the general rules of thumb:
Low-light plants: 5 hours per day
Medium-light plants: 6 to 7 hours per day
High-light plants: 14 to 16 hours per day
Seedlings: 14 to 16 hours per day as well
Seedlings, in particular, need plenty of light once they emerge.
Try to keep your plants on a consistent schedule, just like in nature, where the sun rises and sets daily. Some systems like the AeroGarden let you program the lighting cycle. You can also use plug-in timers or simply turn the lights off and on at the same times each day. Consistency helps plants thrive.
While light is essential, darkness is equally important. Plants need at least eight hours of darkness per day to rest and respirate. Without rest, plants can produce too much energy, leading to stress, burnout, and even collapse.
Overexposure to light can cause yellow spotting on the leaves—this is a sign you’re using too much artificial lighting. If you notice this, reduce the light duration.
Keep a close eye on your plants and observe how they respond to their light schedule. Over time, you’ll figure out what works best.
Also, remember to adjust based on the seasons. In warmer months when daylight is longer, you may not need as much supplemental lighting.
Let me know if you have any questions—I’d be happy to answer them in the comments below. Thanks for stopping by. If there are any indoor gardening tutorials you’d like to see, please comment. Don’t forget to like, subscribe, and share—and hit the bell to be notified of new videos.
Frequently Asked Questions About Full-Spectrum Lighting for Houseplants
How long should I leave full-spectrum grow lights on for my houseplants?
Low-light plants need about 5 hours, medium-light plants need 6 to 7 hours, and high-light plants require 14 to 16 hours of full-spectrum lighting daily.
Do seedlings need more light than mature plants?
Yes, seedlings typically require 14 to 16 hours of light per day to support healthy development and strong growth after sprouting.
Can I leave grow lights on all day and night?
No, plants need at least 8 hours of darkness daily to rest. Constant light can stress them out, leading to overproduction of energy and eventual collapse.
How do I know if my plant is getting too much artificial light?
Yellow spotting on the leaves is a common sign that a plant is receiving too much light. Reduce the light duration if you notice this symptom.
Should I adjust grow light duration during different seasons?
Yes. In spring and summer, natural sunlight increases, so you can often reduce supplemental lighting. In fall and winter, additional lighting is usually needed.
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