Planting
Planting a garden in Minnesota means timing your seeds and starts to avoid frost damage and maximize your harvest—knowing the last-frost dates by county is the key to success.
One late frost can turn a thriving tomato plant into a sad, wilted mess, and planting too early in northern Minnesota’s USDA Zone 3-5 risks stunted growth or worse. But get it right, and you’ll enjoy fresh veggies from June through October.
Whether you’re growing cold-hardy greens like spinach or frost-sensitive crops like peppers, the May 10 average last-frost date (with regional variations) sets the stage for your planting schedule. We’ll break down the best windows for every type of plant.
From succession planting to row covers, you’ll learn how to extend your season without risking frost—so you can make the most of Minnesota’s 165 frost-free days.
Minnesota last-frost dates by county: exact planting timelines
Minnesota’s last-frost dates vary dramatically from the Twin Cities to the northern border, making timing critical for your garden’s success. Warm-season crops like tomatoes and peppers need precise windows to thrive, while cool-season plants can handle earlier starts.
Understanding your county’s average last frost ensures you don’t risk frost damage or miss the growing season entirely.
For example, southern Minnesota (like Winona or Rochester) often sees its last frost by May 10, while northern counties like International Falls may wait until June 1.
This difference means tomatoes planted too early in the north could die back, while southern gardeners might rush their cucumbers if they wait too long.
Below is a county-by-county breakdown of Minnesota’s last-frost dates, categorized into early, middle, and late zones. Use this as your guide to plan warm-season crops, cool-season starts, and succession planting for a bountiful harvest.
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| Region | Counties | Avg. Last Frost | Warm-Season Planting Window | Cool-Season Start |
|---|---|---|---|---|
| Early Zones | Olmsted, Winona, Fillmore, Houston | May 5–10 | May 15–20 | March 15–April 1 |
| Dakota, Ramsey, Hennepin, Anoka | May 10–15 | May 20–25 | March 20–April 5 | |
| Goodhue, Wabasha, Pipestone | May 8–12 | May 18–22 | March 18–April 3 | |
| Middle Zones | Stearns, Benton, Sherburne, Wright | May 15–20 | May 25–June 1 | March 25–April 10 |
| Kandiyohi, Meeker, Morrison, Cass | May 18–22 | June 1–5 | April 1–10 | |
| Renville, Blue Earth, Brown, Faribault | May 12–16 | May 22–26 | March 22–April 5 | |
| Late Zones | St. Louis, Koochiching, Lake, Beltrami | June 1–5 | June 10–15 | April 10–20 |
| Itasca, Aitkin, Carlton, Pine | May 25–June 1 | June 5–10 | April 5–15 | |
| Polk, Norman, Clay, Mahnomen | May 22–26 | June 2–7 | April 3–12 |
Note: Use row covers to extend early planting by 2–3 weeks in all zones.
If you’re planting tomatoes, peppers, or corn, wait until after your county’s average last frost—but don’t delay too long.
For example, in Hennepin County, planting cucumbers after May 25 risks stunted growth, while in St. Louis County, waiting until June 10 ensures better survival rates.
For cool-season crops like spinach or kale, start seeds indoors 4–6 weeks before your last frost. In southern Minnesota, this means mid-March, while northern gardeners should wait until early April. Use seed starting trays with a grow light to give seedlings a head start.
Pro tip: Check the MN State Climatology Office or your local extension service for real-time updates. A late frost in May can push back planting by weeks, so stay flexible.
For succession planting, plan to sow lettuce or radishes every 2 weeks after your last frost to ensure a continuous harvest.
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Remember, soil temperature matters just as much as air temperature. Use a soil thermometer to confirm 50°F+ for warm-season crops like beans and squash. In northern Minnesota, this might not happen until late May or early June, so adjust your timeline accordingly.
Finally, don’t overlook fall planting. In USDA Zone 4, you can still direct-sow spinach or
Minnesota spans USDA Hardiness Zones 3-5, which dramatically impacts what you can grow and when. Zone 3 (northern MN) has shorter growing seasons, while Zone 5 (southern MN) enjoys longer summers. These zones determine whether you can grow cold-hardy crops like spinach in early spring or wait for frost-sensitive plants like tomatoes until after the last frost. The key difference between zones lies in their average minimum winter temperatures. Zone 3 can drop to -40°F, while Zone 5 rarely goes below -10°F. This affects not just planting times but also overwintering strategies for perennials and biennials. For example, asparagus crowns can survive Zone 3 winters, but tender squash plants must be planted after all danger of frost has passed. Here’s how your zone affects planting: *Planting windows are approximate and vary by county. Always check local frost dates. In Zone 3, focus on cool-season crops like kale and peas for early spring planting. These can handle light frosts and even snow cover. Meanwhile, warm-season crops like cucumbers and beans need to wait until soil temperatures reach at least 55°F—typically late May or early June in northern Minnesota. For Zone 5, you can push the envelope with earlier plantings. Start cold frames or row covers in late March to coax out early greens like lettuce or radishes. By mid-April, you might even direct-sow fast-maturing varieties of peas or spinach. However, always be prepared to protect tender seedlings with frost cloth if late frosts linger. Remember, last-frost dates are just averages—actual frost can arrive earlier or later. Use a frost calendar from your local extension office (like the University of Minnesota Extension) for the most accurate guidance. For example, Duluth (Zone 3) might not see its last frost until June 1, while Rochester (Zone 5) could be frost-free by May 10. Adjust your planting schedule accordingly to avoid frost damage or wasted seeds. Pro tip: In colder zones, opt for fast-maturing varieties or use succession planting to stretch your harvest. For instance, plant a second crop of lettuce in late July for a fall harvest before the first frost. This way, you can enjoy fresh greens even in Zone 3’s short growing season. 🌱Hardiness zones in Minnesota: how they affect your planting schedule
Zone
Cold-Hardy Crops
Frost-Sensitive Plants
Planting Window
Zone 3 (North)
Spinach, Kale, Peas, Radishes
Tomatoes, Peppers, Cucumbers
Mid-May to June 1
Zone 4 (Central)
Lettuce, Broccoli, Carrots, Beets
Melons, Basil, Eggplant
Late April to May 15
Zone 5 (South)
Swiss Chard, Brussels Sprouts, Cabbage
Okra, Sweet Potatoes, Corn
Early April to May 10