Haworthias can be crossed between different species in the same genus and even ones in other genera of the Aloeae tribe. On the other hand, pollination can only be successful by crossing two genetically different plants. Many growers consider breeding cultivars as the most fun part of growing Haworthias, which involves the search for new patterns, colors, shapes and textures.
A pair of fine tweezers and a headband magnifier are useful tools for pollination. The tweezers should be sterilized before using.
The flowers on a stalk bloom from bottom to top. When the upper parts of the petals curl outwards, a flower is fully opened and as a male parent, its pollens are ready to be used. However as a female parent, its stigma will take 2~3 more days to mature, and when mature the stigma will elongate and swell slightly. For pollination, use a flower which just opened as the male parent to cross with a female parent which opened earlier.
Carefully remove all the petals of both parents. Then remove all stamens of the female parent. The stamens can be put on a piece of paper for pollinating other plants later. Pluck 1~2 stamen from the male parent and rub the anthers to the stigma of the female parent, until some transferred pollen can be seen. Rub gently to not to break the stigma.
For a flower of the female parent, keep pollinating it for 2~3 consecutive days can improve the success rate. The best time for pollination is from noon to late afternoon. Keep a pollinated plant in a cool and shaded place to prevent pollens from drying out quickly. After ~1 week, if the ovary becomes green and swollen, the pollination was successful.
The seed pod will keep growing for another 1~2 weeks. Once it matures, the pod will snap open to spill the seeds. To not lose the tiny black seeds, when the color of the pod turns darker, loosely wrap it with a transparent sticky tape and leave some padding on the top. This allows the pod to breathe and will keep all seeds inside it.