Pycnanthemum californicum is a native perennial herb of the Sierra Nevada and surrounding California mountain ranges in the mint family (Lamiaceae). Its intensely aromatic foliage and dense clusters of small white flowers flecked with purple make it a productive choice for pollinator-focused and native plant gardens. It goes by Sierra mint, California mint, and mountain mint interchangeably.
The plant grows in rocky, well-drained soils along open slopes and stream margins, and tolerates moderate drought once established. It spreads via short rhizomes, forming manageable clumps that can be divided every few years to control size. In hot inland gardens, occasional deep watering through summer improves performance. Good air circulation around the foliage reduces fungal pressure.
Broadly across the Pycnanthemum genus, Native peoples made leaf teas for fevers and digestive discomfort. The strongly scented foliage discourages some insect pests and draws heavy visits from bees, native wasps, and butterflies throughout the summer.
Powdery mildew
White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.
Root rot
Plants wilt, yellow, and stunt even in moist soil; lower stems and roots turn brown, soft, and mushy and the plant may collapse. Most common in heavy, wet, or poorly drained ground.
Improve drainage and stop overwatering, and never plant too deep. Lift and destroy badly affected plants along with the soil around the roots. Grow in raised or free-draining beds to prevent it returning.