Penstemons are perennials that attract hummingbirds with their long stems of trumpet-shaped flowers in shades of white, lavender, purple, pink and red. Their flowers grow along the stems and make a good addition to cut flower arrangements. Penstemons grow two to three feet high and are native to the hills of California.
Plant penstemons in full sun to part shade in soil that is loose, gravely and very well-drained. Plant them in late spring, after all danger of frost is past and the soil has warmed up. They grow well naturalized on hillsides, on slopes or planted in raised beds.
Space penstemons 18 to 24 inches apart, depending on the mature size of the variety. Grow penstemons from rhizomes or start from seed. Sow seeds directly on the surface of the soil in the garden where they are to grow.
Water regularly, especially during dry periods. Penstemons are shallow-rooted and benefit from frequent, shallow waterings to a depth of three to four inches below the surface.
Fertilize with granulated slow-release fertilizer when planting and at regular intervals during the growing season, following the manufacturer's recommended rate of application. When the buds begin to swell, switch to a granulated fertilizer specially formulated for flowers--this will help them produce more blossoms.
Cultivate shallowly to control weeds because of their shallow root systems, or apply a two inch layer of mulch for weed control.
Remove faded flowers to encourage the plants to continue to bloom.
Cut back to ground level when the foliage fades in the fall. Mulch the roots with a six inch layer of hay or straw to protect the roots from freezing winter temperatures. Remove the mulch in late spring after the weather has warmed.