In What Habitat Does a Periwinkle Plant Live?

Site your periwinkles in full to partial shade. Variegated cultivars tolerate more direct sunlight than all-green types, but keep them well watered. In deep shade, flowering on both types of periwinkle is reduced.

Plant periwinkles in fertile, moist, well-drained soil. Good drainage is key to winter survival and disease resistance, so don't plant periwinkle in low spots that stay soggy or near downspouts.

Space plants 12 to 18 inches apart for full coverage by the end of the second year. For total coverage the first year, plant periwinkle at six-inch intervals.

Spread a two-inch layer of organic mulch, such as hay or shredded pine bark, between plants after planting. This conserves moisture and prevents weeds from growing up between plants. There is no need to mulch again once the plants fill in their designated area.

Fertilize once each spring with a balanced fertilizer containing a nitrogen-phosphorus-potassium (NPK) ratio such as 10-10-10 or other equal numbers. The NPK ratio is required by law to be clearly marked on the fertilizer package. Follow the package directions carefully for the correct amount to apply, which will vary among brands. Don't overfeed, as too much fertilizer can damage the roots. Always apply fertilizer to moist soil; if necessary, water your periwinkles well the day before you plan to fertilize them.

Shear the tops of the plants with pruners, a weed whacker or a high-set lawn mower to rejuvenate plants. Most plantings only need pruning once a year in early spring, to remove winter-damaged leaves. In warm climates or after a mild winter, pruning may not be necessary.