I Have to Know Before I Buy

A customer has a question and I hope we can get some opinions on it, thanks.

"First of all, i ´am a French speaking guy, so please, excuse my English.
I have a small place with 2- 1 000 wths, so i have to put my 20 plants at the same time and harvest them at the same time.
I have two questions on auto-flowering seeds.
1- How many hours of light do they need daily
2- is there any possibilities i can start only one lamp with 10 young plants, and trhee weeks later start the other one with 10 young, and alternate so i could have an harvest every 3 or 4 weeks
I have to know before i buy "


Yes, you can start them at different times to have different harvest times. As far as light goes, you’ll get varying opinions in that. From watching several grow journals, it seems 18 hours of light provides the biggest harvests. But you can essentially run them under any light schedule you’d like.


Although I’m not an auto grower, that seems to be the sweet spot for them. You could also acquire a smaller “nursery” light that requires far less power to run which would be perfect for starts and early vegetative phase.

If you are contemplating a perpetual grow, then you can get lighting more suited for each phase of the plants’ life cycle. I.e. bluer spectrum in veg and more reddish in flower.


I don’t know if all LEDs they sell on Amazon have different settings for veg and bloom. I recall somebody mentioning their light had such a switch. The classic method was to use MH HID lamp during veg and then switch to HPS for flower. You could still do that if you wanted, LEDs are a bit more efficient (160 lumens/watt versus 133 lumens/watt for HPS). They make MH lamps that work with an HPS ballast, so you can just switch bulbs when you go to flower. Of course, for a perpetual grow you would want one of each or two LEDs to use at different switch positions.

Whatever lights you get, you need about 35-50 watts per square foot. So for a square meter grow tent, you would need 376 - 538 watts. With LEDs you can aim near the low end because they are more efficient. If you buy LEDs, find out the real power draw from the mains, not the phony marketing number. They do need more light for flower so you could aim lower for the veg light and higher for the flower light.

If you can do minimal electronic assembly, you can get very simple COB kits and you might be able to specify color temperature when you order them. You want about 5000 K for veg and 3500 K for flower.

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