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Artifical light vs sunlight

- Thu, 20 Feb 2020 09:46:22 EST 2oz2EJ52 No.147196
File: 1582209982192.jpg -(25537B / 24.94KB, 250x201) Thumbnail displayed, click image for full size. Artifical light vs sunlight
Hello. This might be a weird or outright idiotic question. How much difference is there between: artifical light with lower intensity (compared to sunlight) but longer duration AND sunlight but with less duration.
For example 400W HPS lamp that would be on for 18hours a day. Compared to sunlight which would be "on" for about 12 hours a day.
Basically what i'm asking is: should i bother with outside growing if i can provide the proper temperature outside but with less uptime of light as in early-late spring or should i wait till late spring early summer to start?
As i have the choice to either grow in a box or grow outside in a greenhouse but i'm afraid the less duration of light wouldn't be sufficient even if it's more intense for AUTOFLOWERing plants.
Is there a study of some sort or a growers journal regarding this?
Hamilton Dimmlelutch - Fri, 21 Feb 2020 07:28:47 EST 8NnaVizo No.147199 Reply
First at the levels we usually grow cannabis the amount of usable light indoors is absolutely equivalent to sunlight.
The noon sun at the equator is about 1000W per sqm, with an average over the day of 500W at the most.
The rule of thumb of 400W per sqm for indoor lightning provides the plants with about the same amount of PAR (photosynthetic active radiation) because a higher percentage of light is in the 400-700nm region spectral region that plant can utilize.

Regarding your question in a greenhouse that depends. A lower amount of light is absolutely fine for plants that are in the growth phase or early flowering (stretching) phase. If you plan accordingly you can time it so that late flowering happens during the summer for autoflowering plants.
Regular strains however need the 10-12h of darkness which won't happen in the northern hemisphere until late august.
Hugh Blinkinway - Tue, 25 Feb 2020 10:52:04 EST 2oz2EJ52 No.147200 Reply
Thanks. Managed to find some weather stations nearby and checked their measurements for radiation in a day and based on that it's too early for starting outside. Will have to wait till early/mid April or May.
Caroline Drabblehodge - Sun, 15 Mar 2020 01:21:40 EST 6IK8eNOZ No.147214 Reply
Always check your lights PAR values for your lights. Wattage isnt exactly UV output equivilant.

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