Lamp operating hours and effect on plants

Hi, I would like to ask if it is ok to turn on the lamp in the evening, and whether it has any negative effect on the well-being of the plants?

Based on the lamp on duration of 16hrs, turning it on in the evening means that the plant will be receiving light throughout the night. and when the lamp turns off in the day, it will be receiving sunlight throughout the day.

So essentially, it doesn’t “sleep”. Does the plants need to “sleep” to grow well?

Or is it better to adjust the lamp on timing such that it will get a minimum number of dark hours? If so, how many hours does it need?

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I would think it’s okay, some dark time is good for plants, but it doesn’t have to be 8 hours for sure.

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Why would you set up the lamp like this? And what are you growing?

It would be perfect if you could turn on the lamp in the morning and leave it on during the day.

If you leave the lamp on during the night and also the plants get enough light during the day, you may experience leggy growth and some salad greens may tend to bold prematurely. Especially, if you have slightly higher temperature range. But, as said before, it depends on what you are growing.

But, gardening is all about experimenting. Feel free to let us know about your results


A rule of thumb, foliage plants needs 14-16 hours of light per day and flowering plants 12-16.
Plants needs to rest, above will give them at least 8 hours of darkness.



The lamp is quite bright. Using it as a nitelight so no need to turn on other lighting (save energy).

Currently Lavender, strawberry, tomato, french marigold, basil, sweet alyssum. Started 1 week ago.

French marigold, basil, sweet alyssum sprouted.

Temperature range is approx 27 ~ 31°C.

So how many hours of darkness do you recommend?

Previously I have grown strawberry, tomato, basil.

tomato flowered and bear fruit… but only like, 1~2 fruits actually matures. then it dies. the 2 tomatoes like tasteless.

strawberry grew and flowered, but never bear a single fruit, then it dies.

Didn’t thin the plants then (no such guides or advise available 1 year ago). So it may not be attributed t the extended light exposure.

basil grew quite vigorously. Managed to re-pot it. That’s the only thing that is considered a success with my experience with C&G.

I restarted the SGs after about 1 year, and I want to get it right, hence asking for advises from experts.

Just before this latest endeavor, I planted 3 batches of basil, marigold, alyssum, lavender. None germinated. But this is off-topic.

From living in Thailand I learned that some plants like strawberry and tomatoes never got the same good sweet taste as in Sweden, I believe this was due plants growing to fast and did not develop a flavor,

On the other hand there are fruits like for example pineapple and bananas that will ripe in a chilled container during the transport, they do not get the heat and sunlight they need to develop flavors and will therefore never taste as good in Sweden as in Thailand.
This is all outdoor gardening, but the principle is the same. Different factors for different plants, but they all need light and dark, some more some less.


On this topic. I am actually currently running a little experiment of my own on my click and grow light timer. I plugged the system into a smart outlet and put it on a timer. From 5:30am - 12:30pm and again from 12:31pm - 11:30pm. In this way I have extended the light time of my CG9. I did this for a couple of reasons, chiefly my apartment is kept very dark. My CG9 doesn’t really get any actual sunlight during the day or very little on days that I’m home during the day. But I’m not usually home during the day. Lol. By extending the light time last week, I think I’ve already noticed a small uptick in growth rate. :slight_smile:


Im just curious what the results of your experiment was.


I’m growing tomatoes that are twice as big as the last ones I grew. My plants are VERY happy with the extra couple hours of lamp light. :upside_down_face:

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Could you send a picture

The little one was pretty standard for my last plants and the big one is looking awesome.


Wow! Just Wow!


If a Click & Grow SG9 gives plants 12 watts for 16 hours a day. A day length increase of 4 hours would increase the total quantity of light photons by 25% ((240-192)/192*100). Thus meaning 25% faster growth.
It is not suitable for all plants though…


That’s super interesting. My apartment is kept very dark 80% of the time. I really think the extra couple of hours of lamp light every day makes up for a lack of natural light. If my CG9 got a normal amount of sunlight, the extra hours would probably be unnecessary.