How to Identify and Care for an Adelaide Dunbar Common Lilac

1). Identify the Adelaide Dunbar Common Lilac by its medium green foliage. The leaves are either oval or heart shaped and can get up to 5 inches long. The double purple flowers are fragrant and last a long time. They grow on panicles that are 4 to 8 inches in length. This is also referred to as the French lilac--the plant that most are familiar with. This plant can grow up to 20 feet in height and 20 feet in width. It blooms in late spring to early summer.
2). Plant this lilac where it will receive at least 6 continuous hours of sun. Dig a hole that is at least two times the size of the root ball and as deep as the container it is in. If you have poor soil, dig the hole a bit bigger and add a mix of 50 percent original soil and 50 percent compost. Separate the roots. Fill in around the plant and water it well.
3). Keep the shrub watered with at least an inch of water per week during mid spring to mid fall months. The soil should be moist but not soggy. If the soil does not drain well, create a runoff ditch by digging a trough in the ground leading away from the plants. If the problem is not solved with an above-ground ditch, you can create a French ditch. Dig a trench that is 18 to 24 inches deep and fill with gravel. Top with sod.
4). Prune every spring, removing dead, decaying or old wood. This allows for better air flow and helps the plant resist disease. Throughout the growing season, remove any dead branches. Pinch the stem tips of a young plant–this promotes branching. If normal spring pruning does not give enough air flow, you can thin the plant out by removing whole branches at the trunk.
5). Fertilize with a fertilizer with phosphorus when the plant is young. This promotes root growth. Once the plant has become established, use a good all-around fertilizer, unless a soil test shows missing nutrients. Shrubs should be fertilized only once per year.
6). Prevent disease such as verticillium or fusarium wilt by not using nitrogen-heavy fertilizers unless absolutely needed and not over watering. Always remove infected plants.