Obedient Plant 'Crystal Peak White'
Physostegia virginiana 'Crystal Peak White' is a compact cultivar of obedient plant, a rhizomatous North American native perennial in the mint family. The straight species can reach four feet and spread assertively; this cultivar stays at 18–24 inches and increases more slowly, making it manageable in mixed borders and rain gardens. It produces pure white tubular flowers in upright racemes from late summer into fall.
The common name comes from the flowers' tendency to stay repositioned when moved along the stem, a structural trait of the hinged calyx. Plants spread by rhizomes and are well suited to moist, sunny sites including stream banks and low-lying clay-heavy areas. Late-season bees and hummingbirds forage the tubular flowers regularly. Dividing clumps every two to three years keeps spread in check and maintains vigor.
Ecoregions:Northern ForestsEastern Temperate ForestsGreat Plains
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.
Rust
Orange to brown raised pustules on the undersides of leaves, with yellow spotting on the upper surface. Heavy infections cause leaves to yellow and drop.
Remove and destroy infected leaves. Avoid overhead watering and improve air circulation. Apply a sulfur or copper-based fungicide if it spreads. Clear plant debris in fall.