Perennial violas look a lot like their cousins, pansies. But, perennial violas offer the benefit of coming back year after year, adding early-season color to the garden, as well as lots of curb appeal first thing in the season when relatively few other plants bloom. Perennial violas bloom in a wide range of colors, and have a soft, old-fashioned feel that makes them ideal for use in cottage gardens. Because these spring flowers are low growing, they're excellent choices for the front of the border or lining walkways and sidewalks. Hardiness varies by variety; if you live in an especially cold-winter area, be sure to check the hardiness before planting.

Grow perennial violas in full sun (at least 6 to 8 hours each day) or partial shade. Most varieties can grow quite well in shade, but don't bloom as profusely. Water perennial violas enough to keep the soil moist, but not wet. Though these spring-flowering plants can tolerate some drought, they look better -- and bloom better -- with regular watering.

Primula are an easy to grow group of perennial plants which come in many different colours and shapes. Many people thinking of Primula will bring to mind the popular Polyanthus types illustrated left, but in fact there are many different types, shapes, sizes and colours of Primula and they are great garden plants.

Sources = http://www.costafarms.com/plants/viola-perennial
https://www.sundaygardener.co.uk/how-to-grow-primulas.html