We would like to interplant lilacs and rose of Sharon as a sight barrier along a property line (extended blooming is the goal of the combination). What are your recommendations? Are the plants compatible?

Lilacs (Syringa) and rose of Sharon (Hibiscus syriacus) have the same site requirements: full sun and fertile, moist and well-drained soil. Both will tolerate light shade. This is an interesting combination as a shrub hedge in the landscape as they are both shrubs that were used in Midwestern “yards” at the turn of the century and have continued to be part of the Midwestern landscape since the earliest communities were built. Both can be formidable shrubs and should be planted away from the house. You may have noticed how they were often planted in the outer corners of rural, then city and later in suburban yards, or as borders, often in front of hurricane fences. They have also been used as foundation plantings but that is not where they show their beauty best.

The height of the lilac ranges from 6 to 18 feet with a spread of 4 to 15 feet, depending upon the cultivars chosen. The rose of Sharon has a height of 8 to 12 feet and a spread of 6 to 10 feet. We welcome spring with the lilac’s profuse and fragrant lavender, pink, or white blossoms in May and June. When they are finished blooming, the foliage is medium to deep green on arching or upright mounded branches.

The rose of Sharon is the other bookend of the spring-summer season, showing off its big, colorful blossoms in the heat of the summer and still blooming when the children go back to school. The big, bold flowers of the rose of Sharon come in white, pink, lavender, violet or blue and can be flat, single blooms to carnation-like doubles to the newer anemone type that has a single flower with a lacy center. During the summer, when not in bloom, the foliage is dark and dense with three distinct lobes.

Both plants have proven that they are hardy, rugged and versatile in the Midwestern landscape. The common lilac is known to have problems with mildew and can become leggy and open at the base, but there are some cultivars such as Syringa meyeri ‘Palibin’ that are less troublesome. Think about throwing an early-blooming forsythia and mid-season bloomer like a spirea into the combination and you will have continuous color.