Plant of the Week: Grace smokebush

This October brought record high temperatures to New York City. While many people enjoyed the unexpected sunshine and warmth, trees did not adapt as well. The hot and dry fall allowed the trees to continue producing chlorophyll, keeping their leaves green late into the season and resulting in a lackluster fall display. Fortunately, the Grace smokebush was still able to produce its vivid fall color.

Continus 'Grace' is a vigorous shrub capable of growing three to five feet a year and quickly reaching 20 feet tall and 10-15 feet wide. The large leaves emerge burgundy-colored, fade to a green still tinged with burgundy, and develop brilliant orange and red fall color. Smokebush, named for its airy pastel pink inflorescences, appears shrouded in them from late summer to early fall. 'Grace' is an excellent choice for large gardens and landscapes, particularly on the High Line where its dark foliage dramatically contrasts the surrounding birches and grasses.

Grace smokebush is a low maintenance plant. In fact, it responds poorly to pruning often resulting in gangly, whip-like stems. Intermittent coppicing is recommended to rejuvenate foliage color and increase leaf size. Keep in mind that it will affect the following season's flower display. Coppicing is a traditional method of woodland management historically used to continually harvest wood off the same trees. A coppiced tree is cut nearly to the ground and then left to regenerate over several seasons. This technique may be intimidating to the novice gardener, but the resulting foliage is well worth the risk. The gardener here coppices the High Line's Cotinus on a 3-year rotating schedule. He recommends pruning very early in the season, just before bud break, to avoid the sticky sap that stains clothes and can cause allergic reactions.

Cotinus 'Grace' is a garden hybrid, one of five seedlings resulting from a deliberate cross between the American smoketree (Cotinus obovatus) and 'Velvet Cloak' European smoketree (C. coggygria 'Velvet Cloak'). It was raised by Peter Dummer, in Winchester, in the late 1970s and is named after his wife. Cotinus is closely related to Sumac, which is another top fall performer on the High Line. In fact, smokebush was originally placed in the Rhus genus with sumacs but was later differentiated by its undivided foliage and assigned to its own genus. Both Cotinus and Rhus are members of the Anacardiaceae family, which includes mangos, cashews, and poison ivy.

PLANTING TIP:
Cotinus 'Grace' will tolerate a wide range of soils as long as they are well drained. Plant in full sun for optimal flowering and foliage color. Grace smokebush has no significant pest problems but is susceptible to verticillium wilt and powdery mildew in dry conditions.

WHERE TO FIND THIS PLANT:
Grace smokebush can be found in the Washington Grasslands & Woodland Edge (Little West 12th and West 13th Streets) and at 10th Avenue Square (West 17th Street).

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