Penstemon spectabilis is a perennial native to southern California and Baja California, found in chaparral, coastal scrub, and oak woodland edges. It produces tubular flowers in lavender to violet-purple with a pale interior on upright branched stems from late spring into early summer. Blue-green clasping leaves persist through the growing season. Hummingbirds and native bees are its primary pollinators.
It thrives in fast-draining rocky or sandy soil and tolerates extended summer drought once established. Heavy clay or supplemental summer irrigation promotes root and crown rot. Slope planting suits it well because drainage is natural and the roots help stabilize loose soil. Plants self-seed modestly; established clumps can be divided in fall to propagate.
Fungal leaf spot
Brown or purplish spots on the leaves, often ringed with a yellow halo, that spread and merge in warm, humid, or wet weather; heavily spotted leaves yellow and drop early.
Pick off spotted leaves and clear fallen debris to remove overwintering spores. Improve air circulation by thinning, and water at the base so foliage dries quickly. If it persists, apply a copper- or sulfur-based fungicide at the first sign.
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.
Crown Rot
Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.
Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.
Phytophthora Root Rot
Wilting despite moist soil, yellowing leaves, stunted growth, and dark, decayed roots and crown tissue. Vines may collapse during hot weather.
Plant in well-draining soil and avoid waterlogging. Remove and destroy affected vines. Improve drainage with raised beds or amended soil and avoid overwatering.