Rocky Mountain Penstemon
Rocky Mountain Penstemon is a flower in the Plantaginaceae family. It grows best in full sun with dry moisture, and is listed for USDA zones 4-9. Plants reach maturity about 102–138 days after planting and sit about 12 inches apart.
Varieties
1 from True Leaf Market · sorted by days to maturity▸Rocky Mountain102–138 days
Non-GMO; Container; Perennial
120 Days to maturity. Penstemon strictus. Rocky Mountain Penstemon Seeds. Non-GMO, open-pollinated, Premium Quality Seeds, perennial. Rocky Mountain penstemon is easy to grow from seed and ideal for gardens prone to heat and drought across North America. Rocky Mountain penstemon is native to arid pine and juniper forests from Wyoming down to New Mexico and is a tenacious performer in poor soil. Rocky Mountain penstemon flowers are fragrant and simple to grow whether it be indoors or out for compact, urban, or traditional gardens alike. Rocky Mountain seeds promise neat penstemon plants with rich, leafy greens and robust "snapdragon-like" stalks certain to excite any fresh cut arrangement, basket, or bouquet.
View on True Leaf Market ↗
Plant spacing
In a square-foot bed, space rocky mountain penstemon about 12 in apart — that fits 1 plant in each 1-foot square (1×1). Wider rows or containers space the same.
Plan your rocky mountain penstemon planting
Add rocky mountain penstemon to a free GardenDraft plan and get sow, transplant, and harvest dates computed for your ZIP code — with a drag-and-drop bed layout and reminders when it’s time to plant.
Start your free plan →At a glance
Growing timeline
Care & troubleshooting— extension-sourced, with citations
When to feed, prune & water
Harden off seedlings
ProtectionUnusual this time of year.
- Routine careGradually expose plants to the outdoors· every 1 days · ~2 wksstrong evidence — extension confidence
Starting about two weeks before transplanting, set seedlings outside in a sheltered, shady spot for a few hours and lengthen their time and sun exposure each day, avoiding windy days, to prevent transplant shock.
- Routine careEase back on water and transplant on a mild daystrong evidence — extension confidence
Water a little less during hardening (without letting plants wilt) to toughen growth, then transplant in late afternoon or on a cool, cloudy, calm day.
Something looks wrong?
Describe what you see on your rocky mountain penstemonand we'll rank the likely causes — most likely first, least-invasive fix first.
Powdery mildew
Diseasemoderate- CulturalImprove airflow + remove worst leavesstrong evidence — extension confidence
Cut out the most heavily coated leaves and thin for airflow; avoid wetting foliage late in the day.
- OrganicPotassium-bicarbonate or sulfur - label use only· every 1 wk · ~4 wksmoderate evidence — extension confidence
Apply a labeled potassium-bicarbonate or sulfur fungicide weekly per the label. No sulfur within 2 weeks of oil or in high heat.
Slugs & snails
Pestmoderate- CulturalTrap, hand-pick at night, reduce cover· every 2 days · ~3 wksstrong evidence — extension confidence
Pick at night with a flashlight, set shallow beer traps, water in the morning so soil dries by dusk, and clear damp hiding spots.
- OrganicIron-phosphate bait - label use only· every 1 wk · ~3 wksmoderate evidence — extension confidence
Scatter a labeled iron-phosphate slug bait sparingly per the label; it's pet- and wildlife-safer than metaldehyde.
Spider mites
Pestmoderate- CulturalHose down and raise humidity· every 3 days · ~2 wksstrong evidence — extension confidence
Mites thrive in hot, dry, dusty conditions. Spray foliage (especially undersides) with water to dislodge them and reduce dust.
- OrganicInsecticidal soap or horticultural oil - label use only· every 5 days · ~2 wksmoderate evidence — extension confidence
Apply to undersides per label; mites resist many products, so soaps/oils are preferred. Not in extreme heat.
Aphids
Pestlow- CulturalBlast off with water· every 3 days · ~2 wksstrong evidence — extension confidence
Knock colonies off with a strong jet of water in the morning; repeat every few days. Light infestations rarely need more.
- OrganicInsecticidal soap - label use only· every 1 wk · ~3 wksmoderate evidence — extension confidence
For persistent colonies apply insecticidal soap to undersides per label. Avoid open flowers.