Flowers that Hold Up to Summer Heat in the Northwest
Plants that take summer heat in stride freshen our gardens even when we feel like sitting in the shade with a glass of iced tea. Look to the following collection to put on a great summer show.
Chitalpa (x Chitalpa tashkentensis) is a cross between two attractive flowering trees: Southern catalpa (Catalpa bignonioides) and Southwestern desert willow (Chilopsis linearis). The variety 'Pink Dawn' grows into a small, drought-resistant round-headed tree. It blooms for several months in summer and autumn with spikes of light pink, foxglovelike flowers.
Hebe species and cultivars from New Zealand have staged a friendly invasion into mild-winter Northwest gardens. These evergreen shrubs shine in full-sun situations.
Groundcover Hebe pinguifolia 'Pagei' has silver-gray leaves and white flowers; it grows only 9 inches high. 'Wiri Charm' has magenta flowers. 'Great Orme' sports pink-and-white flowers on a 5-foot-high shrub. 'Amy' (shown here) offers violet-purple flowers over burgundy-purple foliage.
There are more varieties of penstemon than you can shake a stick at. Many are native to the Southwest and Midwest, where summer heat is abundant. Garden hybrids grow into round shrubs up to 3 feet tall. Their wide, tubular flowers appear all summer. Tidy their appearance by cutting back spent flower stems to new growth that appears in the leaf axil. In spring, cut back to a 6-inch stem structure. Note: Heat-tolerant penstemons also tolerate drought, deer, and rabbits with ease. Most, however, fail in clay soil.