As compared to the observation of preflowers, forcing clones is an almost foolproof method of determining sex. This method anticipates that the grower has started a batch of plants from seed. After several weeks of vegetative growth, the plants should have branched enough that cuttings may be taken. The cuttings should have at least one node and be at least an inch and a half long.
1. The seed plants are numbered or otherwise made distinguishable from each other.
2. Take 2 cuttings from each seed plant. Each of these are given the same number as their donor plant.
3. Root these cuttings and pot separately.
4. One representative clone of each plant is placed in a separate light proof flowering area and the photoperiod there is changed to 12/12. Please note that since these clones will be discarded after they show sex, that practically any light source will serve our purposes here.
5. The other clones remain in vegetative growth. By the time the flowering clones show sex, the now-identified as female vegetative clones are sexually mature and ready to flower themselves.
6. For larger crops, retain both the donor plant and the non-flowering clone for vegetative growth. Both may be used as mother plants to provide clones for harvest oriented flowering.