In my experience growing and reading about hermaphrodites (herms) to the point that I named one heirloom strain Herman Munster because it always herms heavilly... If you stress a female you can flip it to being a herm, or even all male. Often times they will herm even is they are not stressed (like my Herman Munster strain). The Dutch have done a lot of research on this and there are ways to stress a female plant into becoming male. Usually too much heat, water stress, cold stress, nutrient deficiency, and moving them around too much will do it. There are also certain chemicals that will force a female to become male and force males to become females, but they are not readily available to he public.
Stress aside, the most common way to get herms these days is to plant fem seeds. The thing (and in my view, the biggest problem) about fem seeds is that they are prone to herm on you. Fem seeds are produced by herms that either self pollinated or pollinated a neighboring female plant. That process tends to generate mostly female plants, but at the same time they are also prone to producing hermaphrodites. There are likely other genetics or genetic switching at play here as well though. Thai stick seeds were notorious to herm. Maybe because they pulled all the males and only herms pollinated the few seeds found in Thai sticks, or for some other genetic reason.
MJ is usually a dioecious species with separate males and females, but they can and do produce both types of flowers on one hermaphrodite plant. As a matter of interest, I have only seen female plants herm with male flowers, and I have never seen male plants throw female flowers. It seems to be a one-way ride from female to herm or male, and not the other way around. I have grown out and flowered a lot of males, as I did this year. I forced 4 fem seed females to be all males this year. I collected and froze pollen from them in an experiment to see 1) if I could force males, and 2) if the seeds produced from their pollin on a female next year will create fem seeds. We shall see.
I have experienced that females can and do produce a few random seeds from a herm/male flower that gets missed in inspection from time to time. I keep those seeds for planting in future. Generally those seeds will be self pollinated fem seeds. However, self-pollinated herms will tent to herm even more than herms that are used to pollinate pure female plants. Also when letting males flower like I tend to do to collect pollen, I can pollinate the females, unintentionally. Pollen tends to get everywhere and on everything, and males can pump out huge amounts of pollen, even from just one flower. So beware...
A few seeded tops will not ruin a crop though. You can smoke tops that have been seeded. We did that for centuries (and likely millennia) before they invented sinsemillia. One solution to less herming is to grow using non-fem seeds. Of course then you run about a 50% chance of getting males, but the resulting 50% females will likely not become herms. To produce more females (even if they are genetically 50/50 male/female) grow them in ideal climate and conditions. Pamper the crap out of them and you will likely get more females, even from non fem seeds. Good soil, good sunlight, good fertilizer, a good fungal mass in the soil, and ideal temperatures. Growing outdoors in ideal conditions in greenhouses in Southern Oregon I tended to get about 75% females from sexed landrace seeds.
Stress aside, the most common way to get herms these days is to plant fem seeds. The thing (and in my view, the biggest problem) about fem seeds is that they are prone to herm on you. Fem seeds are produced by herms that either self pollinated or pollinated a neighboring female plant. That process tends to generate mostly female plants, but at the same time they are also prone to producing hermaphrodites. There are likely other genetics or genetic switching at play here as well though. Thai stick seeds were notorious to herm. Maybe because they pulled all the males and only herms pollinated the few seeds found in Thai sticks, or for some other genetic reason.
MJ is usually a dioecious species with separate males and females, but they can and do produce both types of flowers on one hermaphrodite plant. As a matter of interest, I have only seen female plants herm with male flowers, and I have never seen male plants throw female flowers. It seems to be a one-way ride from female to herm or male, and not the other way around. I have grown out and flowered a lot of males, as I did this year. I forced 4 fem seed females to be all males this year. I collected and froze pollen from them in an experiment to see 1) if I could force males, and 2) if the seeds produced from their pollin on a female next year will create fem seeds. We shall see.
I have experienced that females can and do produce a few random seeds from a herm/male flower that gets missed in inspection from time to time. I keep those seeds for planting in future. Generally those seeds will be self pollinated fem seeds. However, self-pollinated herms will tent to herm even more than herms that are used to pollinate pure female plants. Also when letting males flower like I tend to do to collect pollen, I can pollinate the females, unintentionally. Pollen tends to get everywhere and on everything, and males can pump out huge amounts of pollen, even from just one flower. So beware...
A few seeded tops will not ruin a crop though. You can smoke tops that have been seeded. We did that for centuries (and likely millennia) before they invented sinsemillia. One solution to less herming is to grow using non-fem seeds. Of course then you run about a 50% chance of getting males, but the resulting 50% females will likely not become herms. To produce more females (even if they are genetically 50/50 male/female) grow them in ideal climate and conditions. Pamper the crap out of them and you will likely get more females, even from non fem seeds. Good soil, good sunlight, good fertilizer, a good fungal mass in the soil, and ideal temperatures. Growing outdoors in ideal conditions in greenhouses in Southern Oregon I tended to get about 75% females from sexed landrace seeds.
