Planting Guides
When to Plant Green Beans in Denver: Complete Guide + Best Varieties for Zone 5a
Last updated: October 30, 2025
Plant green beans in Denver after May 23 when soil reaches 60°F. This complete Zone 5a guide covers the best varieties for Denver's 148-day season.
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Quick Answer
Plant green beans in Denver after May 23 when soil reaches 60°F. Choose fast varieties like 'Provider' for multiple successions.
TL;DR
Plant green beans in Denver after May 23 when soil temperature reaches 60°F (16°C). For Zone 5a's 148-day season, start with quick-maturing 'Provider' (50 days) followed by succession plantings every 2-3 weeks until July 15. Choose bush varieties for continuous harvests or pole beans for vertical growing in Denver's high-altitude conditions.
Frequently Asked Questions
When exactly should I plant green beans in Denver?
Plant green beans in Denver after May 23 when soil temperature reaches 60°F (16°C) at 2-inch depth. While our average last frost is May 9, soil temperature is more critical for bean germination success than air temperature. I check soil temperature with a thermometer each morning for three consecutive days before planting. In cool spring years, this date might push into early June, while warm springs could allow planting by May 20.
Which green bean varieties work best in Denver's Zone 5a climate?
Phaseolus vulgaris 'Provider' is my top choice for Denver gardeners because it matures in just 50-55 days, allowing multiple succession plantings in our 148-day growing season. Phaseolus vulgaris 'Roma II' handles our intense summer heat well and produces broad, flat pods perfect for fresh eating. For vertical growing in small Denver gardens, Phaseolus vulgaris 'Kentucky Wonder' pole beans maximize space usage while thriving in our high-altitude conditions.
Can I do succession planting with green beans in Denver?
Absolutely - succession planting is essential for continuous harvests in Denver. Plant Provider every 2-3 weeks starting May 23 through July 15. This gives you four separate harvests: early June planting harvests in late July, mid-June planting produces in early August, July 1 planting yields in late August, and July 15 planting matures by mid-September. Each planting produces for 2-3 weeks, ensuring beans on your table from late July through early October.
How do I protect green beans from Denver's unpredictable late frosts?
Keep lightweight row covers ready throughout May and early June since Denver can experience surprise frosts even after our May 9 average last frost date. I've successfully protected beans from 28°F temperatures using floating row covers supported by wire hoops. Monitor weather forecasts religiously and cover plants when temperatures drop below 35°F. If frost damage occurs, replant immediately - the soil is already warm and new seeds will germinate quickly.
What's the latest I can plant green beans in Denver and still get a harvest?
July 15 is the absolute latest for planting Provider beans in Denver. This 50-day variety planted July 15 will mature by September 5, giving you nearly a month of harvest before our average first frost of October 4. Planting later risks losing the crop to early fall cold snaps. For insurance against weather, I often plant a final small succession on July 20 in containers that can be moved into protection if needed.
How do Denver's clay soils affect green bean growing?
Denver's clay soils can form a hard crust after watering that prevents bean seedlings from emerging. I solve this by covering planted seeds with compost instead of native soil. Clay also drains poorly, leading to root rot if overwatered. Amend beds with 3-4 inches of compost and coarse sand to improve drainage. The alkaline pH common in Denver soils (7.5-8.0) should be lowered to 6.0-7.0 using sulfur for optimal bean growth.
Do green beans need special care at Denver's 5,280-foot elevation?
Denver's elevation creates 25% more intense UV radiation than sea level, which can stress plants but also accelerates growth. Ensure consistent soil moisture since our low humidity increases water stress. Pole varieties like Kentucky Wonder actually thrive in our intense light. Watch for sunscald on developing pods during the hottest part of summer, and consider providing afternoon shade when temperatures exceed 95°F. The good news is that our cool nights help plants recover from daily heat stress.
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Nathan Brooks
Nathan is a garden designer in Denver who focuses on water-wise plantings adapted to Colorado's Front Range climate. He grew up in Nebraska, studied environmental science in college, and fell into garden design after spending summers working at a native plant nursery in Fort Collins. Denver's climate is genuinely challenging—low humidity, intense UV, alkaline clay soil, and wild temperature swings that can go from 70°F to snow in 24 hours. Nathan designs gardens that handle all of that without supplemental irrigation once established. He writes about xeric gardening, native plant selection for the Front Range, and the practical realities of high-altitude growing.
