Primula (Primrose). I always thought primroses were difficult to grow, but I’ve found them to be super easy as long as you provide shade and moist soil. There are 425 species of primula. They come in every color of the rainbow and range in size from little 3-inch dwarfs to 4-foot giants. The photo at right shows Primula denticulata, also known as the drumstick primula. Colors range from white through lilac, pink and deep red.