Midnight Duchess Hydrangeas

Origins

• This bigleaf hydrangea cultivar -- Hymmad II -- was developed by Michael Dirr of the University of Georgia in 2002. It was the result of a chance seedling produced by the hydrangea cultivar Nigra, which is also known as Mandschurica. The shrub that supplied the pollen is unknown. After several years of evaluation of its ornamental qualities, Hymmad II was given a U.S. patent, number PP18282, in 2007. It is better known by its trademark name, Midnight Duchess.

Features

• New stems are markedly blackish-purple on the Midnight Duchess hydrangea, making a stark contrast to the deep, dark green leaves that are heart-shaped. Leaves often have a black cast over the green. Flowers occur on branch tips. The flower head is referred to as lacecap: the center true flowers are tiny, but larger flowerlike bracts line the clustered mass. Soil pH does not play a significant role in determining the color of Midnight Duchess' lacecap flower. One key feature is that both alkaline or acidic soils, regardless of the amount of aluminum ions present, create pink to lavender-pink flowers. The blooms do not vary from rosy pink to cobalt blue like in other bigleaf hydrangeas.

Size and Habit

• Midnight Duchess hydrangea grows into a rounded shrub with mature size anywhere from 3 to 5 feet tall and 3 to 5 feet wide. In mild winter climates, where cold doesn't kill back branch tips, this bigleaf hydrangea attains a size closer to 5 feet tall and equally wide if pruning is never conducted. Temperatures below 0 degrees Fahrenheit progressively kill branches, eventually back to the roots. The shrubs must rejuvenate with new shoots from the roots or base of the branches every spring, and therefore may only reach 3 feet tall by 3 feet wide by the end of fall each year.

Cultivation Insight

• Midnight Duchess hydrangea is winter-hardy in U.S. Department of Agriculture plant hardiness zones 6 through 9. However, with a thick layer of mulch over the winter, the shrub may survive into zone 5b. Flowering may be delayed or absent in zone 5 because of the loss of year-old branches from winter cold damage. Grow this hydrangea in fertile, moist but well-drained soil that is rich in organic matter. It tolerates partial sun to full shade conditions. In sandy or drier soils or where the summers are long and hot, it's best to plant this shrub in shadier conditions to limit stress from afternoon heat and lack of soil moisture. Midnight Duchess may also be grown in containers filled with potting mix, but not topsoil.