Like gardenia, dogwood and snapdragon, the potentially finicky Madagascar periwinkle, Catharanthus roseus, is often challenging to grow. It enjoys, but seems to prefer more humidity than it gets here. The happiest plants can get nearly two feet tall and wide in sheltered and humid spots. (They can get even larger in exposed spots in humid climates.) Yet, most of us are satisfied with relatively scrawny plants less than half a foot tall.

Madagascar periwinkle is popularly grown as a warm season annual until the weather gets too cool in late autumn, but it can tolerate a bit of cool weather, and can even survive as a perennial through winter if sheltered. The one or two inch wide flowers have five petals and small red centers, and can be white or various shades of pink, pinkish red, lavender or pastel orange. All parts of Madagascar periwinkle are incidentally toxic.