AUGUST ELEGANCE: 'DIANA'
Mid-August brings the flowering of the rose of Sharon shrub, at a time when garden blooms are sparse. Hibiscus syriacis is an old-fashoned flowering shrub currently out-of-favor with most landscape designers. It has Victorian associations and has been so overplanted throughout the years that it is now often found on small, cramped urban lots growing into houses, in the company of painted dwarves and pinwheels. However, one cultivar of rose of Sharon stands alone, and it's the only Hibiscus syriacus cultivar that The Green Man uses: 'Diana'
In full bloom 'Diana' rose of Sharon is simple, classic, graceful, and a joy to behold unlike its often garish relatives. As a single specimen, 'Diana' works wonders in lawn areas that need a single large specimen shrub as a focal point or near the transition zone from the family living area to the woods beyond. 'Diana' is somewhat formal in appearance so it functions superbly in pairs...and spectacularly as an allee as planted at Longwood Gardens, the former Dupont estate in Kennet Square, Pennsylvania.
The Green Man loves Hibiscus syriacus 'Diana' but proffers several caveats. First of all, all rose of Sharon plants require lots of space and plenty of sunlight and water.
However, 'Diana' is easily-grown in average, medium, and well-drained soil. Rose of Sharon prefers moist, organically-rich soils, but tolerates poor soils and some drought after it is well-established. Although the species is quite tolerant of summer heat and humidity, a specimen may flag during prolonged hot spells so make sure the location of your shrub is within easy reach of water. Large flowers may be obtained by pruning back hard to 2-3 buds in early spring. Otherwise, prune to shape.
'Diana' is vigorous, multi-stemmed, and will max out at about 5-8' tall. Also, it may be trained as a single trunk tree or espalier. 'Diana' features showy, hollyhock-like, 5-petaled, pure white flowers (4-6" diameter) with no eye. Each flower has a prominent and showy center staminal column. Long, early-summer to fall bloom period.
Flowers stay open at night thus making 'Diana' perfect for spacious moon gardens. Also, 'Diana' is a sterile triploid that produces few if any seed pods so it's not weedy. Triangular, lobed, leathery, dark green leaves. A Royal Horticutural Society of Great Britain "Award of Garden" Merit plant.
Some problems make 'Diana' moderately management-free: light susceptibility to blight, canker, rust, leaf spots, aphids, scale, whiteflies, and Japanese beetle.
However, a well-situated and happy specimen should thrive with minimal attention.
