Also known as rose periwinkle or Madagascar periwinkle (Catharanthus roseus), annual vinca is a versatile little stunner with shiny green foliage and blooms of pink, white, rose, red, salmon or purple. Although this plant isn’t frost-hardy, you can grow it as a perennial if you live in USDA plant hardiness zones 9 and above. Collecting vinca seeds from mature plants isn’t difficult, but growing annual vinca from seed is a little trickier. Read on to learn how.
How to Gather Vinca Seeds
When collecting vinca seeds, look for long, narrow, green seedpods hidden on the stems beneath blooming flowers. Snip or pinch the pods when the petals drop from the blooms and the pods are turning from yellow to brown. Watch the plant carefully. If you wait too long, the pods will split and you’ll lose the seeds.
Drop the pods into a paper sack and place them in a warm, dry spot. Shake the bag every day or two until the pods are completely dry. You can also drop the pods into a shallow pan and put the pan in a sunny (non-windy) location until the pods are completely dry.
Once the pods are completely dry, open them carefully and remove the tiny black seeds. Place the seeds in a paper envelope and store them in a cool, dry, well-ventilated location until planting time. Freshly harvested seeds usually don’t do well because germinating vinca seeds require a period of dormancy.
When to Plant Annual Vinca Seeds
Plant vinca seeds indoors three to four months before the last frost of the season. Cover the seeds lightly with soil, then lay a damp newspaper over the tray because germinating seeds of vinca require total darkness. Place the seeds where temperatures are around 80 F. (27 C.).
Check the tray daily and remove the newspaper as soon as seedlings emerge – generally two to nine days. At this point, move the seedlings into bright sunlight and room temperature is at least 75 F. (24 C.).