Knowing when to plant beans in Colorado is the first step to a great harvest. Our state’s unique climate, with its late springs and early falls, makes timing everything. Get it right, and you’ll enjoy a steady supply of crisp green beans or hearty dry beans. Get it wrong, and a surprise frost might end your season before it starts. This guide will walk you through the best planting times for your specific area and bean type.
When to Plant Beans in Colorado – Best Planting Times For
Colorado’s planting dates aren’t one-size-fits-all. They depend heavily on your elevation and the last spring frost. Beans are warm-season crops that hate cold soil and frost. Planting too early is the most common mistake gardeners here make.
Understanding Colorado’s Frost Dates
Your local average last frost date is your key calendar marker. Beans need soil temperatures of at least 60°F to germinate well, and 70-80°F is ideal. You can find your estimated last frost date from local extension resources, but here’s a general guide:
- Eastern Plains (Lower Elevations): Late April to mid-May.
- Front Range Urban Corridor (e.g., Denver, Colorado Springs): Mother’s Day (mid-May) is a traditional, fairly safe benchmark.
- Mountain Valleys & Higher Foothills (Above 7,000 ft): Early to mid-June, sometimes later.
Always watch the 10-day forcast, not just the calendar. A warm April can be tempting, but a May cold snap is common.
Best Planting Windows by Bean Type
Different beans have slightly different tolerances. Here’s how to time it.
Bush Beans (Green, Yellow, Dry)
Bush beans are the go-to for most Colorado gardens. They mature quickly, which is perfect for our shorter growing season. Plant your first sowing 1-2 weeks after your last average frost date. The soil has warmed up enough by then. For a continuous harvest, sow a small block of seeds every 2-3 weeks until about 10-12 weeks before your first fall frost. This method, called succession planting, avoids a glut.
Pole Beans
Pole beans take longer to mature but produce more over time. Wait until the soil is reliably warm, usually at least 2 weeks after your last frost date. They need their full season, so getting them in promptly is key. A tip: if you have a short season area, consider starting them indoors in biodegradable pots 3-4 weeks before transplanting to get a head start. Transplant carefully to avoid root disturbance.
Fava Beans (Broad Beans)
Fava beans are the exception! They’re a cool-season crop. In Colorado, you can plant them as soon as the soil can be worked in early spring, often April. They can handle a light frost and actually prefer cooler growing temperatures before summer heat arrives.
Step-by-Step Planting Guide for Colorado
- Prepare the Soil: Beans don’t need super rich soil, but they do need well-draining ground. Work in some finished compost a week or two before planting. Avoid high-nitrogen fertilizers, as they promote leaves, not pods.
- Direct Sow: Beans almost always do best sown directly in the garden. Plant seeds 1 inch deep. Space bush beans 3-4 inches apart in rows 18 inches apart. For pole beans, plant 6 inches apart at the base of a sturdy trellis.
- Water Wisely: Water the seeds in well at planting. Keep the soil consistently moist (not soggy) until seedlings emerge. Once established, water deeply at the base of the plants once or twice a week, more during hot, dry spells.
- Sun & Heat: Choose a site with full sun—at least 6-8 hours. Beans love warmth.
Navigating Colorado’s Weather Challenges
Our weather keeps gardeners on their toes. Here’s how to protect your bean plants.
Late Spring Frost Protection
If you’ve planted and a late frost is predicted, don’t panic. Cover your seeded rows or young seedlings with a floating row cover, old bedsheets, or even cardboard boxes. Remove the covers in the morning once temperatures rise above freezing.
High Altitude & Short Season Tips
Gardeners above 7,000 feet face a real race against time. Your strategy should include:
- Using black plastic or IRT mulch to pre-warm the soil.
- Choosing fast-maturing bush bean varieties (look for “days to maturity” under 55).
- Planting in the warmest, most sheltered spot you have, like a south-facing wall.
- Focusing on a single, well-timed planting rather than successions.
Summer Hail & Wind
Hail can shred bean plants in minutes. Have row covers or a hail netting structure ready during storm season. For wind, a sturdy trellis for pole beans and maybe a low windbreak for bush types can prevent broken stems and dessication.
Choosing the Right Varieties for Colorado
Selecting varieties bred for cooler climates or with quick maturity pays off. Some reliable performers for Colorado include:
- Bush: ‘Provider’ (very reliable, cold-tolerant), ‘Blue Lake 274’, ‘Jade’, ‘Espada’ (for dry beans).
- Pole: ‘Kentucky Blue’, ‘Fortex’, ‘Scarlet Runner’ (beautiful and edible).
Check seed packets for “days to maturity” and count back from your first fall frost to ensure you have enough time. Don’t forget about our local seed companies—they often carry varieties proven in our climate.
FAQs: Planting Beans in Colorado
Can I start beans indoors?
It’s generally not recommended for bush beans, as they transplant poorly. For pole beans in short-season areas, you can start them in biodegradable pots 3-4 weeks before transplanting to gain time. Handle with extreme care.
What if I planted too early and seeds rotted?
If your seeds don’t come up because of cold, wet soil, simply replant. There’s still plenty of season left. Wait until conditions are warmer before trying again.
When is it too late to plant beans in Colorado?
A good rule is to make your final sowing so that the beans have time to mature before the first fall frost. Count back the “days to maturity” on the seed packet from your average first frost date, then add a 7-10 day buffer for slowing growth in cooler fall temps.
How do I protect beans from early fall frost?
If pods are still forming when an early frost threatens, cover the plants overnight just as you would in spring. This can often extend your harvest by a few precious weeks, allowing more pods to fill out.
Getting your planting timing right is the foundation for a succesful bean crop in Colorado. By paying close attention to your local frost dates, warming your soil, and choosing appropriate varieties, you’ll set yourself up for a productive and rewarding harvest. Remember, patience in spring is rewarded with abundance all summer long.