Viola sororia aka Common Blue Violet

Viola sororia is a small perennial in the violet family. Gardeners know it as common blue violet or woolly blue violet. It is native to the central and eastern United States. Wild plants grow in woods, thickets, meadows, and beside streams. They also grow on damp, shaded banks. This plant forms low clumps from rhizomes, which are underground stems. It has no leafy stems above ground.

Plants grow about 0.25–0.75 feet [0.08–0.23 metres] tall, with a similar spread. RHS places both dimensions in a broader band reaching 1.64 feet [0.5 metres]. The leaves grow together at the base of the plant. They have broad, heart-shaped blades with rounded teeth along their edges. Fine hairs can cover the leaves. The leaves fall away seasonally and may decline in summer heat. Each flower stands on its own bare stalk. Blue and violet shades prevail, though some flowers are white with purple veins.

The main flower display comes in spring. Missouri Botanical Garden lists April through August, with later blooms appearing in spells. Flowers have short spurs and measure about 0.07 feet [0.02 metres] across. Bees and butterflies visit the open flowers for nectar. In summer, the plant also makes flowers that stay closed. These flowers still form fertile seeds. Green capsules have three chambers and mature from April through June in North Carolina. Birds and small mammals eat the seeds. Fritillary butterfly caterpillars feed on the leaves.

Grow this violet in rich soil that holds moisture but drains well. It prefers dappled light, though it can grow in full sun. It accepts clay, loam, or sand across acid to alkaline soils. It also tolerates wet soil and nearby black walnut trees. Sources rate it for USDA zones 3–7 and RHS H7. Use it beneath shrubs, beside paths, or in woodland gardens. It suits rock gardens, borders, and lawns too. Deer tend to leave it alone, but rabbits eat it. It seeds freely and can become a weed in moist, fertile ground.

Serious pest problems are uncommon, but slugs, snails, aphids, and mites may attack. Violet gall midge can also cause trouble. Possible diseases include powdery mildew, leaf spot, rust, and viruses. Young leaves and flower buds are edible raw or cooked. Leaves can thicken soup, while flowers serve as salad garnishes. Both leaves and flowers can make tea. Plants For A Future reports no known hazards. It also records past medicinal uses, rather than proven treatments.