Ludwig Spaeth lilac has been a garden favorite since the 1880s and is still considered one of the best deep purple lilacs available. For the most plentiful blooms, place this deciduous shrub/tree in the full sun with well-draining soil, and give it some room. Many sources say this variety can grow from six to twelve feet tall with a spread of six to eight feet, if not bigger. Removing spent blooms before the seeds begin to set will ensure more flowers in the following year, and keeping suckers trimmed out will prevent unwanted spread. Though deciduous, this lilac could be used as a seasonal hedge or privacy screen with its branches covered in lovely heart-shaped foliage.