12/12 vs Veg and Flower

Today I started 2 plants on 12/12 HPS light and 3 plants on 18/6 MH light. All from the same crop and all just a couple days old. I was told they are "Rainbow Kush" but have no real idea what they are. Bagseed.
I've read that 12/12 from the start will result in faster maturing, smaller plants and I've also read (in Jorge Cervantes "Growers bible") that the stress caused by the 12/12 cycle used before the plants are showing pre-flowers will work against growth so that both sets of plants should mature around the same time anyway. I'll post weekly updates on both groups but for now they all look alike, a 1.5" tall stick with 4 leaves... Currently in 6" pots with Miracle grow potting mix and 25% additional perlite.

I'm going to watch.

12/12 is when you cut the light back you should be 18/6 or 20/4

slk said:

12/12 is when you cut the light back you should be 18/6 or 20/4

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alot of people do 12/12 from seed

It's now the end of week 1. Just to be clear , I'm counting from when they all had seed leaves opened. C and D are the 2 being kept under a 400w HPS on a 12/12 cycle. E and F are under a 200w MH on a 18/6 cycle. So far I don't see a large difference. They all range from 2.5" to 3" both tall and in leaf span. C is lagging a bit but with such a small group I don't think it's significant. I know I said there were 3 in veg but G was accidently crushed by a well meaning individual...
Same watering. No feeding yet.
I don't expect to see much variation until week 3 or 4 myself. We'll see.

I had that in mind too to turn one of my seedlings and one of my clones (clone just week in to rooting) to flower . Was wondering if you could use cfls ?

ninky323 said:

I had that in mind too to turn one of my seedlings and one of my clones (clone just week in to rooting) to flower . Was wondering if you could use cfls ?

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Absolutely you can use CFL for the same effect, flowering spectrum bulbs rather than the veg ones, at 12/12.

The claim made for 12/12 from seed (clone? maybe the same. Maybe not...Hmmmm.) is that the plants will mature faster but with a smaller yield. I am running this test to see how much faster (if at all) and how much comparative yield (if there's a difference). I've also seen talk of some very marked developemental differences in how how the plants will grow. If what I've read is true the mature plants should look very different from each other.

I'm just the curious type.

I don't know if the photos show it but the 2 in veg cycle lights just seem more lush. C is developing a bit differently with the leaves not so well formed.D has a bit of leaf curl but I'm watching it.

there is now a very definate difference between the 12/12 hps and the veg mh. The veg plants e-f are larger with more developed leaves and branchings. The 12/12 have been giving me some trouble with yellowing lower leaves. While the temp difference between the 2 locations is only a couple degrees it is possible (not likely) that under watering may be involved. I have started using the watering meter every day. Advice on the sad 12/12 plants gladly taken.

Plant D turned out to be male today. That's one from the 12/12 side down. Pretty fast. 32 days from seed to showing. Reached 9" in hieght. Good root mass for the size. I removed and destroyed it.

this is a pretty cool little experiment.. i never really understood why anyone would want to grow 12/12 from seed, other than space issues... i too have always read the same things as you about a longer veg period giving a larger yield.. and that forcing the plants to flower before maturity isn't really all that beneficial as it will take almost as long as if you would have waited for the plant to show preflowers.. we must be reading the same books, lol.. i also read jorges grow bible..
that is pretty quick for the plant to show sex from seed, but i have also read that males tend to sex themselves faster than females...
this is definitely a cool idea for a grow, and i will surely be checking back in to see how it goes, and also to see if everything i have read about regarding veg time and yeild really are true or not..
best of luck with the grow..

yea, thanks for doing this experiment and sharing the results...

I think the 12/12 thing really depends on the strain you're growing. Tropical sativas come from places where there's 12 hours of daylight year round so these strains should be better suited to this than a kush or northern lights type plant, which are bred from plants that are native to more temperate climates. So from what I understand, most Sativas are adapted to this light cycle and will basically grow vegetatively under 12/12 until they are mature and ready to flower.

I've been growing skunk x haze, which produces some really nice bud but is a huge pain in the ass to grow due to the mostly sativa genetics. The first run I vegged them to about 12" the way I would with any other plant and ended with 6-foot plants....my lamp sits about 4 and a half feet from the ground. The second time, I vegged only to about 6" and the plants were the exact same height! This time I'm thinking of doing 12/12 from seed to see if I can keep them under 5 feet. If this doesn't work i'm gonna stop growing this strain, which would be a shame because it's a really nice potent heady strain...

my brother grew from 12/12 from seed he said they grew verry quickly but unfortunatly they both snapped probally because of the 12/12 20/4 all the way

Thanks for the encouragement. I didn't think I was the only one wondering...

As you can see, I've transplanted all 3 kids. E and F got 5 gal buckets and C went into a 4 gal as it should not get as large. E and F have shown very nice growth this week and seem happy in the new home. C has also shown good developement. Under 12/12 I don't think I can expect lush growth on this one but it has the same hieght as the others. C only has 5 branch pairs while E and F have 7 each. I seem to have resolved the leaf wilt issue on C which I think was a combination of needing repotting and a PH problem with my water that I now correct for. This shouldn't cause comparison problems as all 3 got the same.

"C", the last of the 12/12, has just shown as female I believe. Tiny little pistils...

The different grow patterns are really becoming apparent now. The 12/12, "C", is the tallest at 9.5" and is strong and healthy with good color. There are a dozen or so clearly visible calyx with 2 little pistil each waving out there. The inner growth is small and C has 7 branchings to the others 8 and 9 branchings. The leaf span of C is much less than E and F as well while E/f are just barely forming calyx, let alone showing sex conclusively. E is 9" tall while F is 7.5". All 3 have shown good health and growth all week but they are certainly developing differently.

There certainly is alot to say today. Plant C (12/12) is now 15" and growing buds. Fully sexually mature and very healthy in appearance. These seeds were put to soak on 10-10 and cracked shell between 10-11 and 10-17.Which makes them 6-7 weeks old from seed. This is the week 6 update because they are 6 weeks in veg. The book says ""The preflowers grow at branch internodes just behind the leaf spur or stipule about the fourth week of vegetative growth when the plant is 6 to 8 weeks old." The book also says "Inducing flowering before preflowers form will not expedite flowering. In fact, flowering will occur at about the same time as if you had waited for preflowers to show!" I still have no preflowers as such on either of the 18/6, E or F. I even posted photos of the node areas and the little bumps they show and nobody else could see sex. They just aren't mature yet and C is budding. I believe the difference between what I read and what I see is the difference between 12/12 from seed and 12/12 from clone. I can see where the books statement would be correct on a clone which was brought to 12/12 after adapting to 18/6 or 24/0, that would seem like alot of stress but it does not seem to apply to 12/12 from seed in this case.
Growth rate has been excellent all around This week. C is 15". E is 13" and F is 10". E and F are filling in differently one from the other. I hope F is not male. It just has that look. Both E and F are filling in more densely and have more nodes than C. C should be ready to harvest in 6 to 8 more weeks (around half way there) while E and F won't be moved to flowering for a week or 2 yet then have 8 to 10 more weeks of flowering time. Once again, the pictures are in order of C,E,F.

End of 7 weeks from seed. We should be at least half way on the 12/12 plant. I have now moved E and F into the 12/12 hps. F is showing definate preflowers but I don't know what! 1st photo is of F's preflowers. anyone able to ID from this what the gender is?
Photo 2 is a group shot. the tall one in the back is C, our original 12/12 from seed. C is 25" tall. E is the next tallest at 17" and F is just 12.5".
Photos 3,4,5 are C,E and F from above. You can see that C is starting to bud and E got a little light burn before I moved them. In fact, that's largely why I moved them. I was going to go 8 weeks from seed but My veg light does not go any higher. Still working the kinks out.
With C towering 8" over it's next rival I must admit that based on what I see today I'd expect C to have the largest yield. I think that E and F will start an "early flowering" growth spurt now so maybe they'll get larger. I always sort of thought that 12/12 plants would look spindly next to veg and flower. Looking right now, C seems nearly As "full" as E. F is bushier but it's also the shortest. I am personally pleased by the health and growth I'm getting on these plants. I'm sure I'll get better as I learn more but these are much nicer than my last plants at the same age.

"F" is male. So now we have C, our 12/12 and E, our veg and flower. C is 34.5" tall with 11 branchings and buds forming up. First picture. E is 21" tall and much bushier with 11 branchings as well. Just started flowering stage, no budding. Second picture. I do think the light burn before changing to 12/12 has slowed E but I expect it to catch up and perhaps get taller than C in the next 8 - 10 weeks. As it seems clear that C will not be ready for harvest in 2 weeks then 2.5 months grow time for 12/12 seems unlikely.

The first picture today is plant F. The male. Bloom already! I want to collect pollen and pollenate a branch or 2 on a plant or 2 in order to preserve the line. I'm getting to like it. C (pic 2) is 38" tall now with buds around 3/4". E (veg and flower, pic 3) is 27" and bushing out nicely. I'm thinking 4-6 weeks to harvest on C and 7-10 on E. I moved the fan because I think E was getting a bit blown. She's drinking alot.