all i do when i want fem pollen is leave the female plant in flower a few weeks longer past harvest, it dont produce as many bananas as the chemical method but i find after about week 2 or 3 of leaving it after harvest it starts to grow pollen sacs at the nodes and out the buds, i then wait till they open then collect the pollen in a pot by tapping the stem, its hard to spot the pollen sacs at the nodes but if you can see the bananans growing out the buds then chances are their is all ready pollen sacs at the nodes and possibly pollen sacs that are open,
so i leave one of my plants in the flower room after ive harvested the rest, using the chemical method i could produce pollen for that grow, but i use the late flowering method and it takes anything from 2 to 3 weeks after the plant is ready for harvest before it starts to self polinate, so i keep checking the plant every couple of days then when i see the pollen sacs i check it every day, i switch all the fans off so the plant is not moving, this stops the pollen falling out the pollen sacs, then i hold the put under the open pollen sacs and give the stem a very gentle tap and the pollen falls into the pot, sometimes the pollen sac falls off as well which is not a problem as it gives more pollen once its totally dry so i leave these in the pot with the pollen,
so i harvest the pollen over the space of about a week, if i left it any longer then the plant im getting pollen from will self polinate, ive not tried letting a plant self polinate so cant comment on the results from them seeds, but they shoud be fem as their is no male genes involved, not sure on the pheno type from a self polination but it should produce a similar plant to the plant that produced the seeds.
anyways i collect the pollen from any pollen sac that opens, using the late flowering method you dont get much pollen per pollen sac, the plant is only trying to self polinate so it dont need to produce masses of pollen, but once ive collected it i leave it in the tub in a dark dry cool place, usually in the bottom of a cupboard in my living room as temps are stable and humidity is not to high, then when i put my plants into flower i wait until buds have started forming, if you use the pollen to early i find the flowering plant dont continue to flower as normal and dont end up as good as it could do, so i wait until the buds have developed and the plant is well into flower,
i then take the female plant into the same room as the pollen is stored in, make sure all windows and doors are closed so the pollen dont get air bourne, i then use a que tip or very small make up/ paint brush, i then gently dip it in the pollen and even though it looks like you dont have much or any on the que tip you probably have plenty, i then gently brush it over the pistils usually on the lower buds on the plant as their less developed as the main buds so have more time to develop the seeds, i get enough pollen to produce around 100 fem seeds so not a lot but enough to give me fem seeds for future grows or breeding programs,
once ive put the pollen on the pistils i want seeds from i leave the female plant where it is for 3 or 4 hours, after that time you should notice the pistils start to shrivel or a slight difference at the end of each pistil, this tells me the pollen is viable and that bud will then produce seeds, so after the 4 hours are up i get a spray bottle and spray the whole plant down making sure all the leaves and buds i put pollen on are getting a good misting, then i let it dry where it is before putting it back in the flower room, the water kills any pollen that might of got dropped on leaves or any that might be still on the buds, so this stops the fans spreading it round the other plants,
then the seeds will develop and some take longer than others, ive had some plants produce seeds in 2 weeks and others in 4 weeks, i just leave the seeds developing until the seed pods are bursting open which is usually a week or so before the plants ready to harvest, so id say at least 4 weeks is needed to produce viable seeds, if you can leave it longer then it can only help produce viable seeds, outdoors the seeds will fall out as the buds die and dry out, but indoors we dont let the plants die so i like to make sure i have at last 4 weeks of grow time before harvest but the more time you can give the more chance you have of viable seeds.
then when i harvest i hang the buds to dry, if you try removing the seeds before the buds are dried its a nightmare and you get in a right mess and end up squashing the buds, but i let it all dry and when its ready to go into jars for a cure i just get the buds with seeds in and gently pop them out their seed pods, some seeds will fall out as the buds are drying as the seed pod shrinks and the seeds pop out so i always have a shoe box under the drying buds to catch any seeds that fall, most dont but some do so the rest i just pop out the buds once the bud is dry,
then i just place them in plastic tubs and leave the lids of for a week or 2 just in case their is any moisture, after that time i put the lids on and ive kept seeds for 6 months and possibly longer just by leaving them in a drawer in a small dark tub, ive not had any problems with them not germing.
i have found that if the seeds have been developing for a long time like 5 or 6 weeks then the seed shells tend to be really hard and wont germ as well so i scuff some seeds if germ rates are low and then it germs as normal,
so to answer your question i leave my plant in flower for a few weeks longer than normal, this forces it to self polinate, i collect the pollen from any bananas that open and any other pollen sacs that open, some plants you get pollen sacs that look like male pollen sacs and these usually appear at the nodes, on other plants you get just bananas and nothing growing at the nodes, but either method has produced pollen and ive got fem seeds from them