Sexing plants?

Noonin NorCal

Active member

Veteran

• Mar 6, 2019

• #1

I have seed plants that are about 7 weeks old... Started them in 4 inch containers and now are in 1 gallon pots.

I can't see any sings yet on the sex of them. They were under 18 hours.....I need to transplant soon, they are getting root bound.

Can i cut the hours from 18 down to 12 hours for a week?
I just want to sex them so i can cull the males out and don't want to buy more soil then i need to.

Would cutting them back to 12 hours for a week until they pre-flower stress them?

And once i get the females i would like to set the timer back to 18 so they can veg again..... Would that be to much stress on them?

Thanks a bunch

 

BOMBAYCAT

Well-known member

Veteran

• Mar 6, 2019

• #2

That is a lot of stress for the plants. I pre-sex all my plants in 1 gal pots so it is possible to do that. The preflowers normally show up on the 3rd or 4th node with true leaves counting from the bottom. If you have vegged for 7 weeks I would expect the preflowers pretty soon. It varies a bit with the different varieties, but they are usually around the same.

 

Switcher56

Comfortably numb!

• Mar 6, 2019

• #3

Short answer NO! So you waste a little dirt. Repot to a "finish pot size" then switch to 12/12. Within a week you should be able to determine sex. Repotting after the 12/12 stresses the plants. Some can determine sex after 7 weeks but most don't have that capability.

 

Noonin NorCal

Active member

Veteran

• Mar 6, 2019

• #4

So i forgot to mention... I don't have space, If i had space i would cut a clone off each plant and flower it.

Just talked with a good buddy and said to just cut back to 15 hours instead of 12

 

Noonin NorCal

Active member

Veteran

• Mar 6, 2019

• #5

Switcher56 said:

Short answer NO! So you waste a little dirt. Repot to a "finish pot size" then switch to 12/12. Within a week you should be able to determine sex. Repotting after the 12/12 stresses the plants. Some can determine sex after 7 weeks but most don't have that capability.

Click to expand...

The plan was to go into 3 gallon from 1 gallon pots, for a month and final homes would be in a greenhouse into 20 gallon fabric pots.

Id love to put them in the GH right now like a seed plant should be, but its a mess in there have to pull weeds and sterilize it before putting anything out there

 

Noonin NorCal

Active member

Veteran

• Mar 6, 2019

• #6

Switcher56 said:

Short answer NO! So you waste a little dirt. Repot to a "finish pot size" then switch to 12/12. Within a week you should be able to determine sex. Repotting after the 12/12 stresses the plants. Some can determine sex after 7 weeks but most don't have that capability.

Click to expand...

I have a high powered dino-lite scope. Im pretty good at just using natural sunlight to see shit. But even under the high powered lens i still can't tell

 

Noonin NorCal

Active member

Veteran

• Mar 6, 2019

• #7

Well, I packed them all into my flowering room. Under 2, 1k hps. 8' x 4' tray

Set the timer for 15 hours

I have limited space in my veg room. which is only a 600 mh, 4' x 4' tray

I dont kneed them to grow much, i just want to sex them already. Chuck the males

once that is done i want to veg them enough to fill out a 3 gallon pot before going into 20's in the greenhouse

Thanks. This shouldn't be difficult but i have limited space, thats the only thing setting me back i think!

 

G

grayeyes

Active member

• Mar 14, 2019

• #8

You can throw them into 12/12 for about six days that should make them sex. Then you will have to cut off the flowers and re-veg under 24 hour light for a while. This is a friend's method of sexing and he has done it for years.

 

mr.brunch

Well-known member

Veteran

• Mar 14, 2019

• #9

Might have been easier to chop a small side branch from each, label them , put them in water and 12/12 them... just stick em in a dark cupboard for 12 hours. At 7 weeks veg they should show in no time.
Sorry it’s probably a bit late for that advice, best of luck