Evaluation of Penstemon as host for Castilleja in garden or landscape

Castilleja Mutis ex L.f. (Scrophulariaceae), or paintbrush, is seldom used in gardens or landscapes because of confusion about hosts and growing conditions. Pairing annual and perennial Castilleja with various Penstemon Schmidel (Scrophularia-ceae) species, however, was shown to be successful over a 2-y period. The most effective host was P. strictus Benth., particularly with C. integra Gray and C. indivisa Engelm. Such pairings now allow horticulturalists a way to incorporate paintbrush into a variety of growing areas. For best results, the microenvironment may need to be balanced to satisfy the growth requirements of both plants.