inferno,
it depends on how you get your females, and how stable the strain is in the first place.
feminized seeds are all the rage these days, and a lot of european breeders offer nothing but feminized seeds anymore. for instance the strawberry cough that i grow is from dutch passion, and were feminized when i bought them (3 years ago now.) i think dutch passion might only sell feminized seeds now too.
they definately produce ass well as no fem seeds and will not hermie, if you either (a) get them from a reliable seed bank or (b) feminize them yourself THE RIGHT WAY.
(1) light poisoning
i have made feminized seeds before using the light poisoning method. this is the most popular method, the easiest, the cheapest, and the worst. . . just turn on the lights for a while in the middle of the night cycle.
when i did it i would go to 12/12 for one week.
the second week of flower i would turn on my lights for an hour dirctly in the middle of the dark cycle. so 12 on, 5 1/2 off, 1 on, 5 1/2 off, and repeat.
then go back to 12/12.
this would reliably produce male sacs from female plants. the problem is that the sacs would grow right inside of the flowers or just above them, and then just make seeds in that flower. . . not spread the pollen all over (maybe a bit on the branches directly under a sac too). this means that all of my plants were only being inbred with them selves (if all of your plants are clones from the same mom, you have this inbreeding problem too)
after light poisoning, and inbreeding, these seed tend to produce more hermies and semi-hermies. all of my light poisond seeds are semi-hermies where the top colas are seedless and all the bottom branches are full of seeds. but those seeds are all semi-hermies or hermies too.
not good if you want reliable sensi.
(2) Gibrillic acid
dangerous to your health. very toxic. i stay away.
(3) STS (silver thiosulfate solution.)
there are two easy to get cheap chemicals available at any photography store called silver nitrate and sodium thiosulfate. you mix a small amount in a specific order to make STS solution. if there is interest i could post instructions to make it. but for now lets just say 20 bucks worth will make 200 1 liter bottles, and each 1 liter bottle will treat 15-20 plants. (and you only treat one or two per cycle)
all you do is take your target female, and spray it down with STS with a spray bottle, until it is drenched and running off the leaves. (if you have autoflowers you do this at the end of the third week) if you have clones, then you just put them in 12/12 the next day.
for about 4 weeks you will get yellowing of leaves and little to no growth. after that you will get PROFUSE male sac. not just a few little balls, but full male tops.
this is usually done 3-4 weeks before your other females are ready to be pollinated. this way you have time to harvest the pollen before you need it for the other ladies.
obviously keep the she-male in a seperate area if you dont wont millions of seeds. then use a paint brush to polinate a few buds for a few seeds.
im gonna want alot of seeds, so il prob grow the male in my clone box, then when the pollen starts to be released, ill just take 4-5 of each plant that i want pollinated (cross bred) and move it into the clone box with the she-male for a few days. . . prob shake she-male over top of them too.
then they'll go back into wheel with the rest of the non-pollinated girls.
there is no inbreeding (unless all clones have same mom, and even then its not as bad as light poison)
all of the seeds are pure female with no more chance of hermie than the original seed. maybe less if its a good cross breed.
also a second application can be made 2 weeks after the first for more profuse male flowers, a temp around 80, and a bloom nute high in phosphorous when male flowers are forming give best results.
wow, long post, did i forget anything?
Thanks Wheel some good info there.
+rep
Pan4