Answer: It will be much easier to just allow the vinca to spill its ripe seeds on the ground. Next spring new plants will pop up. You can try to collect the seeds, but they are tiny so it will be labor intensive. Wherever there is a flower, there is potential for a seed pod. After the petals fall from the flower you will see a swelling which indicates seeds are in the process of being produced. When that seed pod turns a tannish white the seeds are ripe and ready for harvest. Cut the stem below the seed pod and place the entire thing in a paper envelope. The seeds will fall out as the seedpod splits open. This may take a few days after harvest. Use a pair of tweezers to remove the old pods and stems, leaving the seeds in the envelope. Seal the envelope and place it in a glass jar with a lid or into a sealable plastic bag and store it in a cool, dry place. Next spring sprinkle the seeds over the prepared bed and you should get lots of new vinca plants. Enjoy!
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