With its tall spikes of tube-shaped flowers and attractive foliage, the penstemon adds eye-catching color to perennial gardens. Penstemon is closely related to the snapdragon flower and blooms in colors ranging from white and pink to scarlet and purple. Its flowers attract hummingbirds, butterflies and other beneficial insects to the garden. Once established, the penstemon plant requires very little care and tolerates benign neglect. Too much care is more likely to damage the plant than too little care.
Plant penstemon in a well-drained garden bed that receives at least six and preferably eight or more hours of sunlight a day. Penstemon thrives in poor soils as long as they aren’t prone to waterlogged conditions.
Water penstemon when the top 1 to 2 inches of soil feels dry. Provide just enough irrigation to moisten the top 6 inches of soil without forming puddles on the soil surface.
Weed the garden bed once weekly or as needed until the plants reach their full size in early summer. Weeds compete with the penstemon for water and nutrients, which can harm the plants when they are young.
Spread a 1/2-inch layer of compost over the bed each spring just as new growth begins. The compost improves soil drainage and adds some nutrients to the bed.
Cut back the flower spikes once they have finished their blooming cycle. Remove the spikes at the base of the plant but leave the foliage in place until it dies back naturally in fall.
Penstemon grows from rhizomes. Spread a 2-inch layer of mulch over the bed after the first frost to protect the rhizomes from winter temperature fluctuations.
Penstemon flowers are an attractive addition to cut flower arrangements.