Light timing

[bloodshot_eyes]

I'm curious on lighting, alot of people seem to use 18/6 veg 12/12 for flower, I was wondering if there are any advanteges to using say 24/0 for veg and 18/6 for flower. This provides a shorter lights on period than in veg but is it enough to trigger flower of do you need more than 6 hours dark? I was thinking that if you could do that no probs, would the buds grow bigger than on 12/12 as they have 6 hours more light each day or have I got something totally wrong here?

Slightly off topic but I read a paper written buy some canadian guy about marijuana potency and in it it states that high UV radiation exposure causes plants to increse trichome production inturn increasing potency. Are there any grow lights available in Australia other than that big bright one in the sky that produce a strong UV spectrum?

[Luke Skywalker]

You need a minimum usually of 10 hours complete darkness to initiate flowering, due to the required buildup of phytochrome which triggers flowering. Some strains may begin to flower if you drop them from 24/0 to 18/6, but most won't and even those that do begin usually drop back into grow once they realise the dark period isn't getting any longer.

 

18/12 is another matter though, as you'll have a longer day but similar night time. This is relatively easy to program into a good digital timer, but almost all growers utilise a standard 24 hr day rather than a 30hr so that may be evidence there is little advantage. Still, might be worth playing around with it, provided you're not dependent on crop timing.

[Pam]

The UV theory is still unproven. Adding a cfl or MH during flower does help though.

 

MJ needs a 12 hour dark period to flower. You can use 20/4 or even 24/0 in veg but it is believed that the 18/6 allows the plant some rest time, as well as helping to start flowering faster once switched to 12/12

 

The only strain that you can grow under 20/4 throughout is an autoflowering type like LowRyder. You can learn about them at highbred.com. That site is dedicated to LR strains and growing them. It is as good at teaching growing LR as this site is at reg MJ.

Edited March 17, 2008 by Pam

[bloodshot_eyes]

Cheers, makes plenty of sense