Penstemon

These are hardy and tender perennials from North America. They form clumps, 2 to 3 feet tall and produce mostly basal leaves, 2 to 3 inches long. Their flowers grow in loose spikes resembling a snapdragon. They are pouched and up to 2 inches across. They come in most colors and often have a contrasting throat and veins. Picking off the dead flowers will increase the blooms. These plants will behave as perennials in mild climates. Otherwise, they are propagated annually by seeds or cuttings as described below in the appropriate section.

Pot Cultivation

Penstemons will grow in regular garden soil in a sunny or slightly shaded area. Their soil should be moist to on the dry side. The larger flowered varieties should be spaced about 10 inches apart and the smaller ones, 6 to 8 inches apart. The larger flowered kinds usually need support from sticks.

Propagation

Chill seeds a week before planting. Start them indoors at a 70-degree temperature, 12 to 16 weeks before it's safe to plant outside. Grow them at cool temperatures (50 to 60 degrees). Cuttings may be taken in September and inserted in a cold frame. The cuttings are made from the non-flowering side shoots; they should be 3 or 4 inches long. Remove the lower leaves and cut the bottom just beneath a node before inserting into the soil. After they are planted, water and keep the frame closed for several weeks. When they've formed roots, they need slight ventilation; it should gradually be increased. Throughout severe winter weather, protection must be given by covering the frame; on mild days, they should have some ventilation. At this season, the soil only needs watering when it is fairly dry. Once they've formed a good root system, they should be potted individually in 3-inch pots filled with two thirds loam and one third leaf mold, with a decent amount of sand added. As the weather begins to warm in the spring, they are gradually hardened off and eventually planted outside.