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Penstemon
Penstemon
Penstemon blooms from June through August.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Penstemon
Plant it in full sun. It prefers low water. It is hardy in USDA zones 3–8. Expect it to reach about 2.5 ft tall and 1.5 ft wide at maturity, in roughly 2 years (not yet checked).
What was checked
Mature height and spread, 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, and each fact above says which. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
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. In zone 5, the middle of its hardy zones 3 to 8, 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; if you garden near zone 5, the middle of this plant's hardy range, start with zone 5 in April. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Penstemon get?
2.5 fttall5 ft 7 inan adult1.5 ftwideSee Penstemon in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Penstemon
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Penstemon about 1.5 ft apart, center to center, so each plant has room to reach its full width.
Add Penstemon to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Penstemon's height, spread, hardiness zones, sun and trait tags were checked against 15 published sources on August 1, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- NC State ExtensionPlant Toolboxheight, spread, hardiness zones, sun, years to mature size and trait tags
- NC State ExtensionPlant Toolboxheight, spread, hardiness zones, sun, years to mature size and trait tags
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun and trait tags
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun and trait tags
- University of Wisconsin HorticultureUniversity of Wisconsin-Madison Division of Extension Horticultureheight, spread, hardiness zones, sun and trait tags
- Utah State University Extensionheight, hardiness zones, sun, years to mature size and trait tags
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones and sun
- Prairie Moon Nurseryheight, hardiness zones, sun and trait tags
- Chicago Botanic GardenPlant Finderhardiness zones, sun and trait tags
- Lady Bird Johnson Wildflower Centerheight, sun and trait tags
- Mt. Cuba Centerheight, hardiness zones and sun
- University of Illinois ExtensionFlowersheight, hardiness zones and sun
- University of Illinois ExtensionHort Answersheight, hardiness zones and sun
- extension.colostate.eduColorado State University Extensionsun and trait tags
- NC State ExtensionPlant Toolboxsun and trait tags
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Penstemon
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note. A note reports what its source says; where that differs from a fact above, the fact above is this entry's stored value, and its mark says whether it has been checked.
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.
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.
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.
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.
Switchgrass
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.
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; echoes the pink.
Wisteria
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.
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 10 ft, for the layer behind it.
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 6.5 ft, for the layer behind it.
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Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.