Vinca is best grown in full sun areas or areas that get at least 6 hours of direct sunlight a day. Soil should be well drained and these drought tolerant plants do not need a lot of water so be careful not to overwater. Season long blooms bursting with color from late Spring to late Summer for gardens and containers. Grow Vinca seeds indoors 4 - 6 weeks before the last frost is expected. Cover the Vinca Periwinkle seeds with 1/4 inch of potting mix, spray with water to moisten and press down lightly. Vinca flower seeds will not germinate in any sort of light, so cover trays or containers with a black plastic sheet or a newspaper. Lift the plastic or newspaper regularly to moisten by misting. Once Periwinkle seedlings emerge, they need bright light. At about 2 - 3 inches tall, transplant the strongest plants into individual pots. Directly sowing seeds is not recommended, but if you choose to direct sow, follow the same steps as above. Wait until danger of frost has passed and temperatures are consistently warm, and prepare the soil well so that it is light and fine.