Read something about seeds from Holland (you wrote it being in dialogue with MLA earlier, I thought) and I though, can you easily 'sex', or see the difference between a female and male plant, so you only have to harvest the females in the end? How to do that properly, earlier on? (since growing from seeds will give you either sexes in the end of course and yeah, the males plants are pretty useless)
Shitty question? Um, press ctrl/alt/WTF.
There is no way of seeing the gender of a plant that hasn't started flowering yet. The trick is to start by growing twice as many plants as you would like to harvest, but plant them in smaller pots.
Only once you decide to make them flower can you tell what sex it is. As soon as you see that a plant is female, you pot it into a bigger pot. If you see that a plant is male, you either dispose of it, or keep it for breeding.
There are a couple of other options. The seed companies sell "feminized" seeds, which means that they have been specially bred to be females. That is done by using light to force a female plant to become partly hermaphrodite, allowing the plant to be bred with itself, thus creating a clone. All of the seeds from a plant that has been bred with itself will be female (or I presume male, if the original plant was a male that was forced to grow some female flowers.) The problem with this is that you cant really breed these feminized seeds, so you would have to keep buying more seeds from the company.
The other option, and this only works if you are planning on growing huge plants, is to force the plants to flower when they're really young. This allows you to weed out the males. As soon as you do that, you can force the plants to stop flowering again, making them grow fast safe in the knowledge that you will only be growing females.
To "force" a plant to flower, or to stop flowering is very simple. A plant that recieves under around twelve hours light a day will stop growing fast, and start to grow flowers instead.
A plant that gets 16-18 hours a day will not grow any flowers, but instead will grow fast.
Sorry for the essay