This is also called “Myrtle” this popular ground cover, about
six inches tall, sends out runners over the soil surface that root where they
touch ground. The handsome, dark green leaves are about an inch long, and the
April blooming flowers a cheerful blue. You can find varieties that are white
or purple, but I like the old fashioned “Periwinkle blue” the best. There’re
also some varieties with variegated leaves. Periwinkle is probably the best all-purpose
ground cover around and is hardy to at least Zone 5. Though the plant is said
to be native to the West Indies, it first was described in Madagascar. The
periwinkle is a perpetual herb with flowers that can bloom throughout the year,
but heavily depending on the climate.
How to Grow Periwinkle
You can grow periwinkle in sun or shade, though some shade is
preferable, especially in hot climates. Although it is not fussy about soils
and will grow even in poor ones, it likes soil that is moist and slightly acid.
I value it for its rather open growth habit, which allows me to interplant it
with spring bulbs, but it can be sheared to promote denser growth. Source: Charismatic Planet