Most marijuana strains sold these days are in the form of feminized cannabis seeds.
Difference between feminized and regular cannabis seeds?
These were first developed by breeders in the early 2000s and quickly became popular with cannabis growers.
A batch of regular cannabis seeds may include both male and female plants, requiring the grower to ‘sex’ the plant and throw away the males during growth in order to prevent them from pollinating females (which will force them to produce seeds instead of flowers/buds). With feminized seeds, every seed in a batch will produce a female plant that will only produce flowers.