USDA Hardiness Zone 3B spans the northern Great Plains and Upper Midwest, with average annual minimum temperatures between -35ยฐF and -30ยฐF. The frost-free growing season runs roughly from May 15 to Sep 15 โ about 123 days. That is long enough for most warm-season crops if you start seeds indoors 6โ10 weeks before transplanting. Wind exposure and rapid temperature swings are common; mulching heavily and choosing wind-tolerant varieties improves yields. Cool-season crops can be succession-planted for extended harvests into early fall. For a personalized forecast based on your specific zip code, use our free planting calendar. Browse individual plant guides for detailed growing instructions, or explore how USDA zones work to better understand your growing conditions.
๐ฑ Zone 3B Planting Guide
Last Spring Frost
May 15
First Fall Frost
Sep 15
Growing Season
123 days
Planting dates for 100 vegetables, herbs, and flowers โ computed from Zone 3B frost dates.
Browse all 100 Zone 3B plant guides โ
Jump directly to the detailed growing guide for any plant in Zone 3B.
๐ฅฌ Vegetables
๐ฟ Herbs
๐ธ Flowers
๐ Growing guides for Zone 3B
Hand-picked posts from the GardeningByZone blog that apply to your zone.
๐จ๏ธ Printable calendars & worksheets
Instant PDF downloads matched to your region. Print and tuck into your garden journal.
๐ฆ Midwest Regional Bundle โ $5.99 (save $3.49)
Both essential planning tools for the Midwest region โ calendar plus worksheet, bundled at $3.49 off.
Buy bundle for $5.99๐ Midwest Planting Calendar โ $4.49
Month-by-month planting dates for 100 crops across every zone in the Midwest region. Printable PDF.
Buy for $4.49๐ Midwest Planning Worksheet โ $4.99
Map beds, track planting dates, and plan rotations with zone-specific frost windows pre-filled for the Midwest region.
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