If you want to propagate your begonias, you will need shoots from the mother flower. You can also propagate begonias by seed.

Propagating begonias from cuttings
Begonias are propagated by cuttings. This means that you have to cut shoots about eight centimeters long from the mother flower. Remove all but the top two leaves. These should be cut off cleanly and not ripped out. Then fill a glass with water and cover it with cling film. Now pierce several holes and insert the stems of the cuttings. The stem gets enough water, the leaves stay dry.
Plant cuttings
After a few days you can already see the first smaller roots. About four weeks later, the roots are so big that you can put the offshoots in pots. Now you always have to water the offshoots regularly. The begonias should get a bright place with a maximum of 15 degrees to get through the winter well. In addition, there should be good humidity in the room where the begonias are placed. With the right care, you can then enjoy the new plants next year.
Propagating Begonias by Sowing
Begonias can of course also be propagated by sowing. However, this method is not as promising as propagation via cuttings. The problem with this is that only about half of the seeds you sow will sprout.