How far apart do I plant periwinkle plants? Do they need sand in the soil?
Certified GKH Gardening Expert
They aren't very picky. I wouldn't plant them too close together, as they will quickly spread and fill out an area. Maybe start a foot apart from each other. Be sure not to establish these where you will not want them in the future. They can be tricky to get rid of once you get them established. Here is an article that will help: https://www.gardeningknowhow.com/ornamental/groundcover/periwinkle/growing-periwinkle.htm