Sexing plants

Hey all,
I've got a buddy with a bunch of babies grown from seed. He plans on shocking them into showing sex by putting them under 12/12 lighting for a week. If you've used this technique to sex your babies, how early can you do it? I've done this with plants when they're about a foot tall with no problems, but I'd like to know if anyone has done it with smaller plants -- say 6 inches with three or four leaf sets -- and if so how it worked. Can the handle the shock? Did you wind up stunting 'em? Or was it smooth sailing?
Thanks much.

also interested it how long it takes too show sex

What's the rush? If he has multiple seedlings, he will end up with a few ladies. I would veg them for about a month, and then put them on 12/12 light cycle.

Farmer's Hat said:

What's the rush? If he has multiple seedlings, he will end up with a few ladies. I would veg them for about a month, and then put them on 12/12 light cycle.

Click to expand...

exactly what i did. but how long before they show sex on average?

Around 4-7 days. Be patient...

sweet on day 4 now =)

Do you see anything growing by the nodes?

only on a male i chopped. they usually show first?

Farmer's Hat said:

What's the rush? If he has multiple seedlings, he will end up with a few ladies. I would veg them for about a month, and then put them on 12/12 light cycle.

Click to expand...

The rush is less time, energy, and space spent on males. I agree that I usually will sex 'em at about a month if I go from seed, but when my friend asked why I couldn't tell him anything except 'that's how I've always done it.'

A good way to determine the sex of plants is to cut off a clone and sex the clone by putting it under 12 hour light dark cycle. Label the parents and clone from each plant you are trying to sex.

By changing the light cycle of a plant you are putting it into bud mode and then you'll have to put it back in vegitative mode which will stall out the growth by weeks if not a month or more. Th.ere is also the possibility of shocking the plant into becoming a hermaphrodite by playing with the light cycle

Wait until you can cut off a small clone and test the clone with 12 hour darkness, you don't even need to root the clone, you can begin testing it by cutting the light to 12-12 right away. The clone will indicate sex and die but you won't be shocking the parent plant.

I learned this from Ed Rosenthal's Marijuana growers book 25+ years ago, long before the internet. He was the "go to source" for us old school guys, him and Mel Frank, the grandfathers of modern growing.

No matter what the light cycle is a plant will not show sex until it is sexually mature which is usually around 4-6 weeks old. At which time they will preflower even under a long light cycle. I have found it much less stressful to allow them to preflower on their own. Changing light cycles back and forth adds stress and time to the grow.