Penstemon forms dense spikes of tubular flowers in early to mid summer. Flower colors include pink, blue, red, purple, and white. The plants grow 1' to 3' tall, depending on the variety, and look best planted in groups. Smaller varieties are good for rock gardens and the front of the border, while taller types are best in the wildflower plantings or in the back of the border.
Special features of penstemons
Easy care/low maintenance
Good for cut flowers
Tolerates dry soil
Choosing a site to grow penstemons
Select a site with full sun and well-drained soil. Choose a site where the plants will have plenty of room; penstemons don't like to be crowded.
Plant in spring, spacing plants 1 to 3 feet apart, depending on the variety. Don't crowd plants. Prepare the garden bed by using a garden fork or tiller to loosen the soil to a depth of 12 to 15 inches, then mix in a 2- to 4-inch layer of compost. Dig a hole twice the diameter of the pot the plant is in. Carefully remove the plant from its container and place it in the hole so the top of the root ball is level with the soil surface. Carefully fill in around the root ball and firm the soil gently. Water thoroughly.
Apply a thin layer of compost each spring, followed by a 2-inch layer of mulch to retain moisture and control weeds. Water plants during the summer if rainfall is less than 1 inch per week. After the first killing frost, cut stems back to an inch or two above soil line.