Vinca produces flowering vines that require warm temperatures and sunlight to remain healthy and productive. The plant grows as an outdoor annual in most climates, or you can keep it indoors as a houseplant in winter or year-round. Growing vinca indoors successfully requires supplying the plants with similar conditions to those they require for lush outdoor growth. The plants also require support and pruning so their long vines don't become overgrown and the plant remains full.
Plant your vinca in a 6- to 8-inch diameter pot that has a minimum of one drainage hole. Water the potting soil prior to planting until the soil is evenly moist and the excess water flows from the drainage hole in the pot. Plant the vinca at the same depth it was growing in its seedling pot or outside in the flower bed.
Set the pot in a window that receives full sun all day. The plant should receive at least six hours of sun daily during the shorter days of winter.
Pinch back the tip of each stem to the topmost bud. This encourages bushier growth and shorter vines. Pinch back the tips in spring when new growth begins and again in midsummer to keep the plant compact.
Water your vinca when the soil in the top 2 inches of the pot begins to lose moisture but before it dries out completely. Vinca kept indoors typically requires watering every five to 10 days.
Fertilize the plant once a month with a water-soluble balanced fertilizer in the spring and summer. Use the fertilizer amount directed on the package for the size of pot you're using.
Place your potted vinca outdoors in summer if desired. Set it out after the last spring frost and bring it back indoors in the fall before the first expected frost.