After a long winter, it's no wonder so many Minnesotans are dying to enjoy outdoor activities. If you're gunning to get your garden going, take a deep breath and be patient a bit longer. Otherwise, your labor – and the expense of the plants and seedlings – will come to naught.
The WeatherNation blog notes that frost is still quite predictable across the state, so tender seedlings that could not withstand frost will die if they're planted now.
Plants likely damaged by light frost include beans, cucumbers, eggplants, muskmelon, spinach, okra, peppers, pumpkins, summer squash, sweet corn, tomatoes, watermelon, and winter squash. Plants that can withstand light frost include artichokes, beets, carrots, cauliflower, celery, Chinese cabbage, endive, lettuce, parsnips, peas, Swiss chard, escarole, arugula, bok choy and radicchio. Plants that can withstand a hard frost include broccoli, Brussels sprouts, cabbage, collards, kale, kohlrabi, mustard, onions, parsley, peas, radishes, spinach, turnips, leeks, and sorrel.
Bottom line: wait until mid-May to put out your tomatoes, as well as many other Minnesota garden faves.
You, dear metro Minnesotan, are a resident of Zone 4. (Gardeners up north nudge into Zone 5 territory.) That's according to the Plant Hardiness Zones established by the U.S. Department of Agriculture. (Check the zone map here.) Places like Lowe's often use the zone guide to assist gardeners in selecting plants that will grow properly in a particular yard. (Grapefruit and banana plants will NOT have a Zone 4 or 5 sticker.)
The University of Minnesota Extension website offers some practical, precise guidance for gardeners. The website suggests that if you're eager to get your hands in the dirt now, you can start plants indoors. "Start seeds in plastic trays or peat pots that are 3-4 inches deep. A good soil mixture contains two parts loam, one part sand, and one part organic matter," the site suggests. "Sow the seed by making a ¼-½ inch hole...sow 2-3 seeds in each tray cell or peat pot." And, oh yes, think about timing for the growing season. "Start warm-season crops later than cool-season crops. Peppers and eggplant germinate slowly and should be started before tomatoes."
The website at the Farmer's Almanac has gone high tech and offers a way to customize your garden start-up. It offers a Best Planning Date calendar that allows gardeners to customize their planting schedule to their climate zone. It includes suggestions on the optimal time for each region of the country to sow seeds indoors, plant in the ground and ultimately the best time to harvest.