Pistachio Hydrangea Shrub

Pistachio® is the North American trade name for Hydrangea macrophylla 'Horwack', a compact, deciduous mophead hydrangea. Its flower clusters open chartreuse-green and develop red florets with a small blue eye; after deadheading, flowering can repeat on new growth into fall. ## Flowers and Placement The [Chicago Botanic Garden plant finder](https://www.chicagobotanic.org/plant-information/plant-finder/hydrangea-macrophylla-horwack-mophead-hydrangea) identifies 'Horwack' as the cultivar behind PISTACHIO and describes its green-to-red flowers, late-spring blooms on old wood, and later repeat bloom on new growth. It lists a 2–3 ft height and USDA zones 5–9. The plant patent, USPP 25,577 P3, was issued May 26, 2015 ([patent record](https://patents.justia.com/patent/PP25577)). ## Growing Conditions Plant in part shade with moist, well-drained soil. As a bigleaf hydrangea, it benefits from steady moisture and protection from hot afternoon sun. [NC State Extension](https://plants.ces.ncsu.edu/plants/hydrangea-macrophylla/) describes the species’ shade preference, old-wood flowering, and general landscape uses. ## Maintenance Water during dry periods and mulch around, but not against, the stems. Keep older stems until their late-spring flowers finish; remove spent flower heads to tidy the shrub and support its documented repeat flowering later in the season.