In Minneapolis our average last frost is April 30 according to the Farmer's Almanac, and our average last known killing frost is May 10 according to Bachman's. Our last known frost is May 25. Using this tool from bioarray I generated the following planting schedule with the last known frost date of May 25, since we have had a warm winter and spring I figure you could bump up these dates a few days to a week if the weather seems to still be nice. I altered some dates from this tool, when I felt they sounded wrong based on other sources and experience. I also added planting dates for vegetables not mentioned with this tool that I plan to plant myself based on prior research and experience and Mother Earth News.
3/23 Sow broccoli, kale, cool weather lettuce, escarole, eggplant and thyme seeds indoors (9 weeks before last frost)
3/30 Sow pepper seeds indoors (keep temp above 78*F for germination). Also sow indoors marigold, parsley, basil and beet seeds. (8 weeks before last frost).
4/09 direct plant beets (Beets remain undamaged even when temperatures drop into the mid-20s)
4/11 As soon as the soil can be worked its time to sow peas, fava beans, arugula, and radish directly in the garden (I plan to also direct seed broccoli, lettuce and kale) (up to 6 or 7 weeks before last frost).
4/13 Sow tomato seeds indoors. Sow cabbage seeds indoors. (6 weeks before last frost).
4/20 Transplant lettuce, broccoli and kale seedlings into the garden (use row cover if necessary). Sow more cool-weather lettuce seed indoors. (4 weeks before last frost).
5/4 Sow pumpkin, cucumber and zinnia seeds indoors. Direct seed turnips (3 weeks before last frost).
5/11 Sow summer squash, watermelon and melon seeds indoors. Sow 2nd planting of peas directly in the garden and direct sow carrots and parsnip, beans, swiss chard, cilantro. Plant potato and onion sets. (2 weeks before last frost).
5/18 Sow 2nd cool-weather lettuce crop, more beets, spinach indoors or in garden. (1 week before last frost).
5/25 Sow directly in garden seeds for sunflowers, nasturtiums. Plant 2nd crop of radish. (Week of last frost).
Mother earth News says: Sweet Potatoes keep slips moist and wait to plant them until the soil temperature is consistently above 70 degrees. So plant now if the soil temp is above 70 degrees.
6/1 Transplant tomatoes to garden. Plant seeds for corn, beans and soy beans directly in garden. (1 week after last frost).
6/08 Sow 3rd cool-weather lettuce crop indoors or in garden. Transplant peppers, pumpkins, squash, cucumbers and melons to the garden if the soil is well warmed. (2 weeks after last frost).
6/29 Sow warm-weather lettuce crop (Summer Crisp type) indoors or in garden. Sow 2nd crop of beans, 3rd crop of radish in garden. (5 weeks after last frost).
7/20 Sow 2nd warm-weather lettuce crop (Summer Crisp type) indoors or in garden (8 weeks after last frost).
8/10 Sow 3rd warm-weather lettuce crop (Summer Crisp type) indoors or in garden. Sow 3rd crop of beans, 4th crop of radish in garden. (11 weeks after last frost).