How do I sex using a paper bag?
Get a small paper bag or something similar that is lightproof (a paper bag will not be suitable for strong H.I.D lighting), and a plastic coated twist tie.
Select a plant that you would like to sex and choose a growing tip. Take the paper bag, place it over the top of the selected tip and seal with the twisty tie. Then, to simulate the flowering phase, simply remove the bag after the 12hr dark period, and replace when the 12hr day cycle ends.
After 7-14 days, the growth-tip you covered should start showing signs of its sex.
Caution should be taken when closing the bag too tightly around the branch.
A small opening should be left open to allow air exchange and prevent heat buildup. Black materials tend to heat up and the branch may suffer from excess heat, causing wilting.
"There is plenty of air inside the paper baggage because it would hold its own blown up shape...sorta balloned over the branch tip."
Contributed by: luckyleaf
This is for people that dont have room for clones or just want to know the sex of there plant without takeing and rooting early cuttings.
Things you need:
1 can of black spray piant
1 box of plastic ziplock baggie (sandwich bag size)
Take the plastic baggie and spraypaint the outside of the baggie, then find one of the lower branches that is furthest from the light (this will insure that light reflection on the black paint isnt too intence for heat buildup)and just simply slip the baggie over the branch for 12 hours of darkness.
If you have painted the whole baggie, then no light will get through to the branch when the lights are on. You will see sex on that one branch in 7 to 10 days in most cases.
I have done this many times on inside and outside plants.