Well,this topic has certainly been discussed alot of times....there a few guaranteed ways to make female seeds,such as spraying them with giberrilic acid,or some product called SensaSoak....then theres ofcourse the "Banana Method".Some people SWEAR by it,claiming that after doing this the seeds were 100% female,and its super easy and inexpensive to do..read up on it later,but for now,Ima explain briefly.
Materials:Bananas,Seeds,Paper Towel,Seeds,Ziplock bag
First,get 2 normal yellow bananas from the supermarket.Peel the bananas,and save the "peels"..now get a ziplock bag,and throw the peels in there..use the paper towels to prevent the seeds from actually touching the peels.Now close the bag tight,and leave this in a dark,cool area...As the bananas "rott",they give off a natural gas called Ethylene..this gas is used to ripen many crops faster,and is theorized to actually feminize cannabis seeds..it has been tested on other legal crops,and yes there was 100% female ratios!!
Now every other day or two,open the bag and let it air out,just as if the seeds were "curing"...once the peels get very rotten,replae them with fresh ones...do this for ATLEAST 2 weeks..and just germinate as normal!!
This is still a "theory"in the cannabis community,however test it out for yourself!!Make sure to document the results !!!