How to Grow the Annual Viola Flower

Plant the viola flower during spring in a location that consists of rich, moist, well-drained soil and receives partial shade throughout the day. Apply a 2-inch layer of peat moss to the planting site and use a garden spade to work it into the soil to increase fertility and drainage. Space viola flowers 7 to 12 inches apart.

Apply a thin 1-inch layer of mulch over the ground surrounding the viola flower to insulate the soil, deter competitive weeds and improve moisture retention. Do not allow the mulch to touch the plant's crown, as this can lead to rotting and fungal diseases.

Water the viola flower about once every seven to 10 days during spring, summer and fall to keep the soil consistently moist, but not soggy. Apply water directly to the soil during the early morning hours to minimize the risk of disease caused by wet foliage.

Feed viola plants once every two months using a balanced 10-10-10 NPK complete fertilizer. Apply following the manufacturer's instructions, and then water thoroughly to release the nutrients into the soil and prevent the risk of root injury.

Prune the viola whenever necessary throughout the year to prevent it from growing in an unwanted direction. Remove faded or dead viola flowers, also known as dead-heading, to prolong blooming and encourage the formation of new blossoms.