Cross breeding cannabis can be easy and fun. However, there are some rules to follow to produce offspring that are healthy and genetically stable. Before you start, you should know that cannabis can express itself sexually in three ways: male, female, and (less commonly) hermaphrodite. Male plants produce pollen sacks, and female plants have calyxes, which become the casing of seeds should the plant become pollinated. Should the plant not be pollinated, the calyxes swell and become “buds.”
Hermaphrodites, or hermies, will have pollen sacks and calyxes. Hermies may take the form of plants with pollen-containing stamen protruding from the pistils of the buds.
As you would expect, pollination of the female plant occurs when pollen from the pollen sacks or stamen encounter the female calyxes. This happens when the pollen sacs burst open and release their contents (stamen simply release pollen since they have no sac surrounding them). Once this takes place, the calyxes on the female will begin to develop seeds as they swell.
At this point, it’s important to understand that pollen from pure males is your best option when shooting for male and female seeds. If pollen is used from a hermie, you will get hermie offspring, which will cause your plants to pollinate themselves and produce less desirable flowers.
When you have determined the sex of your plants, separate them by sex so you will be in control of the pollination process. What you’re shooting for is the pollination of the most desirable female samples by the most desirable male. As a cross-breeder, you’re also choosing distinct cultivars that embody the characteristics you’re seeking.
Once you have chosen your plants, take the male plant when it begins producing pollen (when the sacs begin to split open) and collect the yellow powder. This can be accomplished by shaking the branches while holding a receptacle below the pods. Alternatively, a breeding chamber can be used.
When your females are ready for pollen, they will have white hair-like strands from pistils (later reddish) protruding from the calyxes. Upon these is where the pollen is to be applied with either a Q-tip or a fine brush.
After the seeds are ready (4-8 weeks), breeding continues with backcrossing (i.e., inbreeding). The resulting seeds are planted and generate hybrid cultivars. Once again, the most desirable plants are chosen. To create genetic stability, the desirable sample is bred with itself or the parent. After crossing and backcrossing (sometimes extensively), you have a more stable cultivar that will produce plants with the traits that you desire.