Some tips for growing penstemon plants include never pruning them in the fall, only planting them in areas without damp or cold winters and placing them in sunny locations. First, choose a planting location with light, well-drained soil, preferably with access to full sun for best flowering.
Till the top 15 inches of soil at the planting site, and mix it with 4 inches of compost to enrich and lighten the soil. Dig a hole that fits the plant's root ball, providing up to 3 feet of space between plants for sufficient growing room. For locations with excessively wet or cold winters, plant the penstemon in a pot that can be taken inside once temperatures start dropping.
After planting the penstemon and tamping down the soil, water the plant well. Mulch the ground underneath the plant with shredded bark or coarse gravel to inhibit weed growth. Once the plant becomes established, only water it with 1 inch of moisture once a week so that the soil is moist, not waterlogged. Avoid overwatering the plant as this can cause root rot. Fertilize the plant in the spring with even ratio granular plant food, and then give it a diluted water-soluble fertilizer before and after blooming.