How to Fertilize Rocky Mountain penstemon?
Low-concentration penstemon feed every three weeks spring through fall

Rocky Mountain penstemon · Penstemon strictus
Also known as: stiff beard-tongue
Grow in fertile, well-drained soil in full sun or partial shade. In cold areas, protect plant overwinter with dry winter mulch. See penstemon cultivation
Low-concentration penstemon feed every three weeks spring through fall