Duration of light exposure for seedlings
Most farmers use artificial light in the seedling systems on their farms. One really handy thing about artificial lights is that you can set them to turn on and off by themselves using timers.
But how long to keep light on your seedlings?
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Balancing light and electricity costs
Although this does depend some on type of light and type of crops, for most situations growers are going to need 12-18 hours per day of light.
Your place in that range depends on the costs of two things: real estate and electricity. Which one is inherently higher for your facility?
This gives you four situations.
1) If the cost of real estate is higher, then you want to move things through your space quickly. This means that you will be paying for more hours of light (18 or so) to move crops along.
2) If the cost of electricity is higher but you have plenty of space, then you’ll want to reduce lighting a bit (12 or so hours). This means that your crops will grow slower.
3) If both costs are equally high like they are at our farm here in Laramie, then you’ll find a balance. We give our crops about 14 hours each day.
4) If both posts are equally low, then go ahead and run them fast, at about 18 hours a day. (Just remember to give crops everything else that they need as well, like airflow and CO2, or they won't be able to use all that light.)
Don't forget to harden your seedlings before transplant!
Remember to harden off your seedlings before transplanting them! Hardening seedling includes hardening them to things like temperature and humidity, to reduce plant shock. It also means hardening them to light.
As you harden your seedlings, start changing the seedling environment to be more like the main grow out system environment, bit by bit.
When it comes to artificial lighting, things can get confusing in a hurry.
To be successful, however, indoor farmers have to know not only how their plants use light, but what lights are best suited for their operation.
Unfortunately, this information is not always easily accessible, and if it is, it's usually a little biased.
The Modern Farmer's Guide to Artificial Lighting is our straight-forward, no BS guide to help you make informed decisions about your lighting needs.