When Do Wildflowers Bloom in Wyoming?

Penstemons color Wyoming yards in June, and the show rolls on through late summer as the taller natives take over. Wildflowers here follow a short, bright season shaped by cold winters and a growing season that can be brief at altitude.

When Do Wildflowers Bloom in Wyoming?

Native wildflowers bloom from June through September in Wyoming. Penstemons open first, usually in June, and the later bloomers carry color from July to September. Frost can arrive in any month at higher elevations, so plants there rush through the season.

Blanketflower is another choice for dry, sunny, well-drained spots, though many of the commercial varieties are non-native hybrids. Native plants suit the local pollinators, so start there and add non-native ornamentals selectively. Last spring frost falls between May 7 and May 18 at the reference station in Cheyenne, and roughly 130 frost-free days at 6,000 feet leave a modest window for growth.

Why Wildflowers May Not Bloom the First Year

Annual wildflowers bloom the first year. Native perennials work underground first, building roots, and often take a year or two to flower. A planting that looks like green leaves in its first summer is usually doing exactly what it should.

While you wait, mow the planting high during the first year if weeds crowd in. Keep spring-sown seed moist until it germinates. A fall (dormant) seeding does not come up in fall. The seeds wait in the soil over winter, since many natives need a cold, moist winter before they germinate, and they sprout the next spring.

Fall seeding in October or November suits Wyoming well, because seedlings use fall and winter moisture while spring soils can dry out quickly. Penstemons from such a sowing may still need a season or two before they flower.

What to Do After Wildflowers Bloom in Wyoming

Leave the spent flowers standing so the seeds can ripen and drop. Self-sown seedlings fill gaps the following spring, and the seed heads of late bloomers like Maximilian sunflower stay useful well into fall.

Fall is also the moment to extend a planting. Scatter new seed in October or November onto bare soil, press it in rather than burying it, and let winter do the work of preparing it to sprout.

Cut back old stems once the season is over, either in late fall or at the end of winter before new growth starts. Leaving them through winter gives the seed a chance to scatter first. Penstemons prefer lean, dry ground, so skip the compost and fertilizer when you tidy up.

Where to Get Wildflower Advice in Wyoming

Local growing conditions vary a lot with elevation, so advice from people who know your ground pays off. Two places are worth a call or a visit.

• University of Wyoming Extension offers guidance on native plants and penstemons, so check there before choosing seed.
• Your county extension office can tell you which natives suit your elevation and soil, and it is a good first stop before the October and November sowing window.

Common Questions

Can You Plant Wildflower Seed in Spring in Wyoming?

Yes, though spring-sown seed must stay moist until it germinates, and spring soils can dry out quickly depending on unpredictable precipitation. That is why a fall seeding often does better.

What Kind of Soil Do Penstemons Like?

Lean, dry soil. Garden conditions should mimic the plant’s native habitat as closely as possible, so avoid rich, wet beds.

Should You Choose Native or Non-Native Wildflowers?

Consider natives first, since they are adapted to the environment and the local pollinator community. Non-native ornamentals can also feed pollinators, so choose them selectively.