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Zone Guides6 min readMarch 6, 2026
Zone 5b Planting Guide 2026 | Denver, Salt Lake City, Omaha Garden Calendar
Complete planting guide for USDA Zone 5b (Denver, Salt Lake City, Omaha). Get exact 2026 planting dates, frost dates, and best varieties for zone 5b gardens.
USDA Hardiness Zone 5b Quick Facts
- Minimum Temperature: -15°F to -10°F (-26.1°C to -23.3°C)
- Average Last Frost: April 10-25 (April 18 average)
- Average First Fall Frost: October 5-20
- Growing Season: 135-160 days
- Best Planting Window: April 25 - May 10 for warm-season crops
Major Cities in Zone 5b
Primary Cities: Denver, CO • Salt Lake City, UT • Omaha, NE • Kansas City, MO • Lincoln, NE • Colorado Springs, CO
Also includes: Parts of Colorado, Utah, Nebraska, Kansas, Missouri, southern Michigan, and northern Indiana
Get Your Exact Zone 5b Planting Dates
2026 Zone 5b Planting Calendar
March - Indoor Seed Starting
| Crop | Start Date | Transplant Date | Notes |
|---|---|---|---|
| Tomatoes | March 5-20 | May 1-10 | Indeterminate varieties do well here |
| Peppers | March 1-15 | May 10-25 | Start early — peppers need heat |
| Eggplant | March 10-25 | May 15-25 | Warm soil is critical |
| Herbs (Basil) | March 20 - April 5 | May 10-25 | Very frost sensitive |
April - Cool Season Crops
| Crop | Direct Sow Date | Harvest | Notes |
|---|---|---|---|
| Peas | April 1-10 | June-July | Tolerate light frost |
| Lettuce | April 5-20 | May-June | Succession plant every 2 weeks |
| Spinach | April 1-15 | May-June | Bolt-resistant varieties recommended |
| Radishes | April 5-20 | May-June | Quick 25-30 day harvest |
| Carrots | April 10 - May 5 | July-August | Succession plant monthly |
May - Warm Season Planting
| Crop | Plant Date | Harvest Start | Notes |
|---|---|---|---|
| Beans (Bush) | May 5-25 | July-August | Direct sow after soil warms to 60°F |
| Corn | May 10-25 | August-September | Standard-season varieties work |
| Squash (Summer) | May 10-25 | July-September | Plenty of season for full production |
| Cucumbers | May 10-25 | July-September | Succession plant for extended harvest |
Best Varieties for Zone 5b
Tomatoes - Reliable Performers
- Celebrity (70 days): Disease-resistant determinate, great yields
- Early Girl (50 days): Fast to fruit, reliable
- Mountain Merit (75 days): Late blight resistant
- Juliet (60 days): Prolific grape-type
- Cherry tomatoes: Sun Gold, Sungold, Sweet Million
Peppers - Proven Winners
- Sweet: California Wonder, King of the North, Carmen
- Mild Hot: Anaheim, Poblano, Hungarian Wax
- Medium Hot: Jalapeño, Serrano
- Note: Superhots are possible but need a long indoor start
Cool Season Stars
- Lettuce: Buttercrunch, Red Sails, Salanova mix
- Spinach: Bloomsdale, Space, Tyee
- Peas: Sugar Snap, Oregon Sugar Pod, Little Marvel
- Carrots: Bolero, Napoli, Yaya
Zone 5b Frost Information
Critical Frost Dates for 2026
- Last Spring Frost: April 18 (average) — Range: April 10-25
- Safe Planting Date: May 1-10 (add 1 week for safety margin)
- First Fall Frost: October 12 (average) — Range: October 5-20
- Latest Recorded Spring Frost: May 8 (Denver area)
2026 Climate Considerations for Zone 5b
- Altitude Factor: Denver-area gardeners at 5,000+ ft face stronger UV and faster soil drying
- Variable Spring: Front Range can swing 40°F in a day — harden off gradually
- Hail Risk: Common in Colorado May-June — use row covers or hoop tunnels
- Low Humidity: Western zone 5b is much drier than eastern — mulch aggressively
Frost Protection Strategies
- Row Covers: Floating row cover adds 4-6°F protection
- Wall of Water: Standard technique in Denver for early tomatoes
- Raised Beds: Warm faster in spring than in-ground beds
- Mulching: Straw mulch conserves moisture and moderates soil temps
Zone 5b Success Tips
Soil and Site Preparation
- Soil Test: Western zone 5b often has alkaline soil — may need sulfur
- Drainage: Rocky soils in mountain areas drain fast — add compost for water retention
- Amendments: Most zone 5b soils benefit from 3-4 inches of compost worked in each spring
- Wind Protection: Especially important along the Front Range and Great Plains
Season Extension Techniques
- Start seeds indoors: 6-8 weeks before last frost for warm-season crops
- Use transplants: More reliable than direct seeding for tomatoes, peppers, eggplant
- Succession planting: Stagger cool-season crops every 2-3 weeks
- Fall gardens: Plant second lettuce/spinach crop in mid-August
Common Zone 5b Mistakes
- Planting too early: A warm March doesn't mean frost-free — wait for consistent warm nights
- Underwatering: Western zone 5b is dry — drip irrigation is worth the investment
- Ignoring altitude effects: Higher elevations mean cooler nights and stronger sun
- Skipping wind protection: Great Plains and Front Range wind desiccates young plants
Ready to Master Zone 5b Gardening?
→ Get Your Personalized Zone 5b Calendar
Exact dates, variety recommendations, and frost alerts for your specific location
Monthly Zone 5b Garden Tasks
March
- Start warm-season seeds indoors under lights
- Order seeds and plants
- Prepare garden beds when soil is workable (often late March)
- Prune fruit trees before bud break
April
- Direct sow cool-season crops outdoors (peas, lettuce, spinach, radishes)
- Continue indoor seed starting for late crops
- Harden off early transplants
- Apply compost and turn beds
May
- Transplant warm-season crops after last frost and soil warmth
- Direct sow beans, corn, squash, cucumbers
- Mulch around plants to conserve moisture
- Install stakes, cages, and trellises
Related Zone Guides
- Zone 5a Planting Guide
- Zone 6a Planting Guide
- Complete Spring Planting Calendar
- Tomato Planting by Zone
Last updated: March 6, 2026 | Zone 5b data based on USDA Plant Hardiness Zone Map 2023 and NOAA climate normals