Many penstemon species and varieties prefer well-drained soils and full-sun exposure. Many varieties are evergreen and while most bloom in the spring, there are some that flower during the summer months.
These perennials thrive in clay-based or rocky soils and require no soil amendments or fertilizers to bloom year after year but really all perennials can benefit from well-seasoned compost worked into their planting beds and penstemons are no exception. Most penstemons grow in alkaline soils; therefore they do well in Parker County. It is good to know your soil pH because this can determine the varieties of penstemon you can grow for the greatest success.
penstemons have trumpet-like blooms arranged on multiple flower spikes and colors range from blue to white and many shades of purple and pink. Some to look for are Penstemon cobaea, commonly called prairie foxglove; P. triflorus, known as Hill Country penstemon; and P. baccharifloius, commonly known as rock penstemon.
Prairie foxglove is native to our area and in spring it produces large, bells of white, pink or lavender and is a real standout in the landscape. Prairie foxglove is an evergreen perennial and its fuzzy foliage is welcomed to the winter garden. It prefers sunny locations but will tolerate some afternoon shade. Hill Country penstemon is evergreen but its blooms are smaller and are a rich, dark pink. Both can be grown from seed and plants will produce plenty seeds if left to mature, which usually takes about three months. If planted together, these two will cross and produce some really beautiful variations.
Rock penstemon is a summer-blooming perennial. It produces red blooms from June through August and many times into October. This penstemon likes rocky, well-drained soils and is a great plant for dry areas and rocky hillsides. Rock penstemon is low-growing with a spreading habit and is evergreen in North Central Texas. To keep it looking well groomed, a light shearing in spring is sufficient. It is unusual for this penstemon to reseed. Do not plant this perennial in wet areas.
Researched by Parker County Master Gardener La Donna Stockstill