Here we are... God Bless Overgrow again. I do use first method and it really works, additionaly, i know a guy who tried both of them and got positive results. This is the way for produsing feminized seeds.
LIGHT-POISONING METHOD: During the first three weeks of flowering, turn the lights on for an hour during the middle of the dark period. That is, 12 hrs. on, 5.5 hrs. off, 1 hr. on, 5.5 hrs. off, and repeat for the first 3 weeks, after which you may return to the normal 12/12 light cycle. This causes a plant to go "hermie" and pollinate itself, as well as any other female in the room. You must use plants originating only from female seeds or clones to ensure that no male chromosomes are present. The resulting seeds will produce NO MALE PLANTS!
GIBBERELLIC ACID TREATMENT: Select your favorite female plant and spray it from approx. two feet away (first under the leaves, then on top). This must be done 2 weeks before the plant is put into the flowering light cycle, thus the need to start with female seeds/clones. DO NOT SMOKE BUD TREATED WITH GIBBERELLIC ACID! Spray the plant again after 2 weeks have passed, and place it under 12/12 lighting. This plant will "hermie" and pollinate itself and other females present. It will not produce as much pollen as a pure male, thus less seeds. However, these seeds will be 100% female.