When to Plant Fall Flowers in Colorado – 2026
Published: April 27, 2026
Colorado sits in USDA Zone 5b (population-weighted primary). Plant fall flowers in Colorado from April through May. Average last spring frost: April 7; first fall frost: October 22; frost-free growing season: 198 days. The bloom season for fall flowers is fall.
Fall Flowers Planting Dates in Colorado
Plant fall-blooming mums, asters, and sedums in spring or early summer for fall bloom. Fall-planted pansies and ornamental kale provide color into November in Zones 6+. Plant bulbs for next fall: dahlias in spring; tulips in fall.
For Colorado specifically, the recommended planting window is April through May. This window is based on the state's population-weighted USDA Zone 5b — but Colorado spans multiple climate zones, so adjust based on your local conditions. Coastal, mountain, and inland areas within Colorado can vary by 2 to 4 weeks from the state average. The 198-day frost-free growing season in Colorado is about 6.5 months frost-free. good cool-season lawn climate extending into november.
Always check current local forecasts before planting frost-sensitive species. The 'last frost date' is an average — actual frost can occur 2 weeks after the average date in cold years. For warm-season annuals (petunias, zinnias, marigolds), wait at least 1 week past the average last frost date to ensure consistently warm soil. For cool-season annuals (pansies, snapdragons), planting 2 to 4 weeks before last frost is appropriate.
Best Fall Flowers Varieties for Colorado
For Colorado Zone 5b, choose varieties rated for your zone or one zone colder for reliable performance. Below are the top fall flowers cultivars suitable for Colorado's climate.
Plant in spring for established perennial mums; nursery-pot 'florist mums' purchased in fall are usually sold as one-season annuals.
Native New England aster and New York aster bloom September through October. Spring planting; established plants are very long-lived.
Drought-tolerant perennial with pink-bronze blooms in September. Spring planting. Excellent for cutting.
Cool-season annuals planted in late summer or early fall for color through November (Zones 6+) or year-round (Zones 8+).
Plant tubers in spring after last frost. Late-summer through fall bloom. Lift and store tubers in Zones 7 and colder.
How to Plant Fall Flowers in Colorado
Sow method for fall flowers: transplant (summer planting for fall bloom). The practical steps below apply to Colorado's climate and the typical first-year planting timeline.
- →Plant fall-blooming perennials (mums, asters, sedums) in spring (April through June) for established root systems before fall bloom.
- →Plant fall-blooming bulbs (saffron crocus, autumn crocus, fall-blooming species cyclamen) in summer (July through August).
- →Plant cool-season annuals (pansies, ornamental kale) in late summer through early fall for immediate cool-weather color.
- →Pinch growing tips of mums in early summer to encourage bushier growth and more fall blooms.
- →Choose full sun (6+ hours) for mums, asters, and sedums; part shade for pansies in Zone 7+.
- →Water consistently during establishment; once established, fall perennials are drought-tolerant.
- →Apply slow-release fertilizer in spring; avoid late-summer nitrogen which promotes tender growth before frost.
- →In Zone 5 and colder, leave fall-blooming perennials standing through winter for crown protection; cut back in early spring.
Fall Flowers Care Calendar for Colorado
Spring (Colorado last frost: April 7): The main planting window opens after last frost when soil reaches 10°C (50°F). For warm-season fall flowers, wait at least 1 week past last frost. Apply slow-release fertilizer at planting for first-season vigor.
Summer: Water consistently for the first month after planting; established plants need watering only during extended dry periods. Cool-season types may struggle in summer heat — provide shade or accept summer dormancy.
Fall (Colorado first frost: October 22): Prime planting window in Zone 7+; cool-season annuals provide color through fall. Apply final mulch layer after first hard frost.
Winter: Most plants are dormant. Avoid foot traffic on frozen ground. Plan next year's plantings — order seeds and bare-root stock for spring.
Frequently Asked Questions about Fall Flowers in Colorado
When should I plant fall flowers in Colorado?
Plant fall flowers in Colorado from April through May based on the state's primary USDA zone (5b). Plant fall-blooming mums, asters, and sedums in spring or early summer for fall bloom. Fall-planted pansies and ornamental kale provide color into November in Zones 6+. Plant bulbs for next fall: dahlias in spring; tulips in fall.
What USDA zone is Colorado?
Colorado spans multiple USDA zones, but the population-weighted primary zone is 5b. The state's average last spring frost is around April 7 and first fall frost around October 22, giving a frost-free growing season of about 198 days. Adjust planting dates based on your specific local microclimate — coastal, mountain, and inland areas within the state can vary by 2 to 4 weeks from the state average.
Which fall flowers varieties grow best in Colorado?
For Colorado (Zone 5b), choose varieties rated for your zone or one zone colder for reliable winter survival. Garden mums (Chrysanthemum × morifolium) (Zones 5–9) is widely planted across most US zones. Asters (Symphyotrichum) is another strong choice (Zones 3–8). Match the variety to your specific microclimate and sun exposure for best results.