# Grow Lights On A Timer Or Not?



## happychick (Sep 20, 2010)

Should I put my grow lights on a timer, or should I just leave them on all the time?

I just finished getting set up and have been planting today - 

Thanks


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## Ardie/WI (May 10, 2002)

Use a timer or you'll exhaust them trying to grow all the time.


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## happychick (Sep 20, 2010)

Ok, how long should the lights be off of a night? 2 hours, 6 hours?
Also, does turning the light off only appy to after the plants have germinated, or should they always be turned off some of the time?

Thanks


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## wolfwalkerpa (May 24, 2007)

I turn my lights on in the morning and off at bed time. Around 16 hours. good luck


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## radiofish (Mar 30, 2007)

Well for a lower electric bill, better plant heath, to have them ready to be transplanted outside: use a timer. Use a grounded (3 prong) timer, that is rated for the amount of power (current) that the lights will be drawing through it when everything is turned on. Or multiple timers on different outlets, depending on your setup.

During the growth stage I would not use less than 16 hours of light going up to 18 hours, followed by a period of darkness. That way the plants are used to a normal cycle of natural daylight when they are moved outside to a cold frame, in hardening them off to the outdoor environment.

Watch the height of your seedlings/ plants as they are growing, to make sure that they don't grow against the light source. You will have to move plants and adjust the heights of your lights above the plants often. But not so far above the plants, in that they become 'spindly' as they try to get closer to the light source.

Plus if you are being charged different rates by your power usage during certain times of the day (higher rates per kilowatt/ hour - during business hours), you can run the lights at night when cost per kilowatt hour is less. Like it is here where I am at in California, and having those dang 'smart' electric meters.


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## Jeffery (Oct 25, 2011)

I have been growing seedlings and houseplants under lights for many years and I agree with the comments provided by radiofish. I use shop type fixtures with two standard 40 watt florescent bulbs. For seedlings, keep the lights on 16 to 18 hours a day. Some types of seed need light to even germinate. Adjust the height of the lights to stay as close as possible to the seedlings without actually touching them. Be sure to plant your seeds in clean new potting soil to prevent disease. I also believe that a bit of air flow from an oscillating fan develops sturdier plants. 
.


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## Callieslamb (Feb 27, 2007)

I tend to break timers. I tend to leave the lights on too long. And I tend to forget to them back on if I turn them off. I have great transplants every year. What's best would probably depend on how easy it is to access the light switch.


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## happychick (Sep 20, 2010)

Ok, thanks for the great advice guys! I will put my lights on a 16 hour timer.


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## NickieL (Jun 15, 2007)

I can't figure out how to use a timer so I turn em on when i get up and turn them off right before I go to bed.


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## Paquebot (May 10, 2002)

Looks like everyone has it about right. 16 on, 8 off. Or as Nickie said, on when you get up and off when you go to bed. 

Martin


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## MD Steader (Mar 11, 2010)

You know, I never even though about putting them on a timer. I've always just left them on around the clock.


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## jwal10 (Jun 5, 2010)

I use a light as needed, more when the plants are young. My greenhouse gets great light on sunny days and the plants don't need the light, then. I use a timer set for 16 hours and a dusk to dawn eye kind of hid in the shadows. When it gets bright enough it goes off. I have 2 small 12 volt fans blowing air across the plants 24/7, keeps fungal problems out....James


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## Paquebot (May 10, 2002)

Some species do indeed go to sleep during the night. When tomatoes are still in the cotyledon stage, they will nearly close up during the night and then open in the morning. That's their natural cycle. Leaving lights on 24/7 disrupts that.

Martin


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## bama (Aug 21, 2011)

Are grow lights necessary? I just have my seeds in the kitchen which gets a good amount of natural light, but they are kinda spindly looking.


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## Paquebot (May 10, 2002)

bama said:


> Are grow lights necessary? I just have my seeds in the kitchen which gets a good amount of natural light, but they are kinda spindly looking.


"Kinda spindly looking" means not enough light. Only south-facing bay windows can supply enough sunlight which is close to natural.

Martin


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## happychick (Sep 20, 2010)

bama said:


> Are grow lights necessary? I just have my seeds in the kitchen which gets a good amount of natural light, but they are kinda spindly looking.


Grow light really help keep your plants from getting 'leggy', you don't have to have them, but they really help! You can use florescent strip lights (blue spectrum) instead of the fancy 'grow lights' in seed catalogs (really expensive).


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