Inducing Pre-flowers

Wondering if there are any old SOG seedling growers out there.

I've never been in this situation before were I have a packed veg/flower room and clone/veg room, I wanna get the clones in with the seedlings in the veg/flower room but need to execute 30 or so males before I can do so.

Thus I am in situation where I need to sex some 1 month old seedlings so I can flower them off.

Does anyone know of a way to provoke/induce pre-flowers earlier or in a more pre-nounced way?

Only thing I can think of is dropping the light schedule.

Obviously time will tell but I'm curious as to any techniques out there for doing this.

Yeah, I just ended up having to get rid of 5 plants that turned out to be males... they were vegged for at least 2 months and some change...

Usually my plants will show pre flowers after a month and half while vegging...
I really wanted those plants to be girls...


Only way I know is to put them into 12/12...!!!...

Knock a couple hours of light off

Can fell your pain, know it to well. Think that is the biggest drawback to doing larger seed populations indoors, running out of space, and everything else waiting to be able to kill the males.


The phylos testing, you can sex them at cotyledons. Supposedly its legal to no matter where you are located, since you are only shipping a smear of genetic information, not a plant.


Have seen friends, rushing to put seed starts out in Spring, stick the plants in a completely dark closet for a few days, to induce sexing quicker. Myself I never tried it, so I cant say with certainty, but I do feel like it has some merit.


Lastly, recently I had someone mention that Kelp may prolong sexing, as in if your waiting to sex, don't go nuts on the kelp. Myself I love kelp, so hard to stay away.


I feel like a lot of it is genetics, one cross will sex in 3 weeks, another takes 6.


Gl, and enjoy chopping the males and regaining some space!

Mr^^

Not sure about inducing preflowers. I think they have to be a certain age before they will begin to show whether you drop the light hrs or not. At least 6 weeks with most strains.
Some strains will be more prone to hermis if induced before they are mature.
I always liked to take clones from the plants and put them to flower so you don't slow down the bigger seed plants.

Peace GG

12/12 for 4 days and then back to whatever veg schedule you use 18/6 or 24/0. That is what I always did when I started seedlings to put outside. I learned it from another outdoor grower. You don't want or need to go longer then 4 days or you risk needing a reveg period. It is a huge waste of manpower and resources to plant unknown males outside and sometimes seedlings would not preflower until 12 weeks or so which puts cloning and planting way behind. At around 5 leaf nodes tall go to 12/12 for 4 days. If your plants have more nodes it doesn't matter it still works.

Interesting, I have read the same thing about Kelp MedResearcher and haev used it outdoors in conjunction with a full cocktail to bring photosensitive plants back from early flower. You really can't avoid kelp when using mostly organics, it's in everything.

But light schedule manipulation seems to make the most sense. iTarzan, any issue with revegged growth at 4 days? I.E. gnarled shoots form growing tips?

I never had them look like they were revegging after doing this. I don't think it really triigers them to flower because young seedlings don't react like that. When you plant seeds outside they don't start flowering because they are sensing the dark is getting less every day and they are not sexually mature (alternating leaves). This is why you can strike seeds in the outside plot in early spring and not have them flower and then a reveg.

When you do the 4 days of 12/12 inside you are doing it to seedlings that are immature (still have 2 leaves on each node) and they are more resistant to the light change but it does speed up preflowers.

When people grow 12/12 from seed it takes quite a few weeks until the seedlings respond. If you started seeds at 11/13 and kept increasing the light a few minutes every day they would never flower even if it took a month to get to 12/12 because the nights are growing shorter to the seedlings. It is time to veg and grow. It is spring.

In the above post (post #8) I meant "react like that" not "really like that" so I edited.

I've used the 12/12 trick before with success as well. I would do two days 12/12 around the 5th ot 6th node. Then back to 18/6. A week later preflowers should be visible.

I myself will be doing a 48h straight darkness as a friend of mine told me. I will update when done

NoseBat said:

I myself will be doing a 48h straight darkness as a friend of mine told me. I will update when done

Click to expand...

Let us know how its goes.

I'm gonna pull 2hrs of light off down to 18/6 from 20/4 and see if that helps. I would do the 2-4 days of 12/12. However this strain of mine has showed sensitivity/early flowering on more than one occasion. So best not to poke the dragon I think.

I start my outdoor seedlings on 15/9 in april to mimick june 1st light cycle when they go out, they have always shown sex before june with a few exceptions.

So I did a 48 h light off scheme with 7 regular plants (2 uzbek, 5 Cookies hybrid) and I got 2 female preflowers in the uzbekis the afternoon after the darkness. Next morning I watched some male preflower in one of the hybrids. And in the next 2 days I have seen nothing more.
My conclusion is that 48h is not enough for all the plants. Uzbekis will probably be the most fast flowering of these so they showed their sex, but the hybrids didnt have time for that. So next time I'll be doing 4 days of 12/12 or 3 days light off.

I've learned that most modern types are more prone to show preflowers when kept root bound early in. It doesn't work with the landraces necessarily, depending upon the origin and how worked, or wild the line is. But the trick I believe besides this, is knowing the stock your growing and being able to segregate by the size and structures.

Forcing the light cycles like so to induce earlier flowering or "preflowers" isn't going to always be beneficial with today's common cross bred weed, there's a higher odd of hermaphrodites in a lot of today's "strains" and the littlest things can bring these traits to surface.

When I was a kid growing in my closet, I early in my learning curve would trigger seedlings into early flowering with 12/12 being utilized around a week or less. Anything else longer would often induce flowering that would take a while to reverse. Eventually I realized how detrimental this was and ineffective in the long run.

Once you get a really good grasp with identifying the individual sex traits you won't have the time to do things like this, as it is pretty easy to narrow down the two with high accuracy and even a perfect call being made time after time with your seedlings/plants.

A lot of the hybrids out there tend towards having predominant preflowers anywhere from the sixth node to the eleventh, even though most can be found once the fourth node is well developed and branching out. Then the higher nodes tend to be easy to sex utilizing a magnifying lens if necessary.

Best of luck with your endeavors, I have a tray of three week old hybrids that I made and I will be sorting today looking at the boys I'll need to cull alongside any weak unwanted phenotypes ��