Penstemon
Penstemon
Penstemon blooms from June through August.
Mature size, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not.
Growing Penstemon
Plant it in full sun. It prefers low water. It is hardy in USDA zones 3–8. Expect it to reach about 2.3 ft tall and 1.3 ft wide at maturity, in roughly 2 years.
When to plant Penstemon
Plant Penstemon in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. For the middle of its hardy zones 3 to 8 range, spring means April to June and fall means August or September. Once settled, it blooms from June to August.
Month-by-month timing for your zone is on the planting calendar: for the middle of its range, start with zone 5 in April.
Good to know about Penstemon
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Worth knowing
The name comes from the flower's fifth stamen: sterile and tufted with hairs. Those hairs are functional, forcing a visiting bee deeper into the tube. per NC State and Xerces
Drainage depends on species
Most penstemons need sharp drainage and rot in wet clay, but P. digitalis tolerates clay and moisture and even works in rain gardens. per Colorado State and NC State
Hardiness varies by species
The genus page lists zones 5 to 8, but cold-hardy garden species reach zone 3: Husker Red 3 to 8, P. hirsutus 3 to 9. Match species to your zone. per NC State and Wisconsin
Hummingbird and bee magnet
The tubular, nectar-rich flowers draw hummingbirds and many native bees (bumble, mason, leafcutter, sweat), plus butterflies and moths, and support a specialist mason bee. per Xerces
Deer and rabbit resistant
Generally deer resistant and rarely browsed by rabbits, though a hungry white-tailed deer will still nibble it. Count it moderately resistant, not deer-proof. per NC State and Penn State
Short-lived, so let it seed
Many penstemons are short-lived, especially in rich or wet soil. Leave some seed capsules to mature and self-sow, and volunteers will keep the stand going. per Colorado State
Not toxic despite the name
Despite the species name, foxglove beardtongue is not true foxglove (Digitalis) and lacks its cardiac-glycoside poison. Penstemon is not considered toxic. per NC State
What pairs well with Penstemon
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
Goldenrod
Shares full sun and low water; overlaps, then carries the display into mid fall; both are strong pollinator plants; its seed heads stand through winter, for structure and the birds.
Rock Cress
Shares full sun and low water; blooms in mid spring, before this one opens; both offer pollinator forage, in different months; evergreen, so the bed keeps its shape through winter.
Creeping Phlox
Shares full sun and low water; blooms in mid spring, before this one opens; both are strong pollinator plants, and they feed in different months; lower at 6 in, for the front of the border.
Flowering Crabapple
Shares full sun and low to moderate water; blooms in mid spring, before this one opens; both are strong pollinator plants, and they feed in different months; pink sits close to purple on the wheel.
Lilac
Shares full sun and low to moderate water; blooms in mid spring, before this one opens; both offer pollinator forage, in different months; taller at 9.8 ft, for the layer behind it.
Rosemary
Shares full sun and low water; blooms in early spring, before this one opens; both are strong pollinator plants, and they feed in different months; evergreen, so the bed keeps its shape through winter; they only overlap in zones 7 to 8.
Viburnum
Shares full sun and low to moderate water; blooms in mid spring, before this one opens; both offer pollinator forage, in different months; taller at 6.6 ft, for the layer behind it.
Switchgrass
Shares full sun and low water; overlaps, then carries the display into mid fall; its seed heads stand through winter, for structure and the birds; taller at 4.9 ft, for the layer behind it.
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