With winter temperatures that can dip below -30 degrees F, Minnesota can be a challenging place to grow fruit trees. Many types of tree fruit will not survive winter, while others will have their blossoms killed by late spring frosts, wiping out their crops for the year. Of all of the commonly-cultivated fruit tree varieties, apples are the hardiest, and the best choice for the home gardener to successfully reap a crop in Minnesota. Two other types of fruit trees, crab apples and mulberries, are reliably hardy throughout Minnesota. They can be counted on year after year to produce a crop.
Some varieties of apples (Malus hybrids) grow and reliably produce a crop as far north as USDA hardiness zone 3, which encompasses the northern portion of Minnesota. Still other varieties are reliably hardy through zone 4, in the southern half of the state. Choose these hardy apple varieties that bloom late in the spring. They'll survive the arctic winter temperatures and bloom after all danger of frost has past, ensuring that the fruit develops. Varieties hardy through USDA zone 3 include Prairie Spy, Lobo and Keepsake. Good choices for apples that can be grown in zone 4 include Haralson, Honeygold and Fireside.
Grown primarily as ornamental trees, many varieties of crab apples (Malus hybrids and cultivars) are hardy throughout Minnesota. Crab apples are defined as any apple that is 2 inches or less in diameter. Larger varieties of crab apples are prized for use in making apple jelly. Trees can be dwarf or full size with fruit sizes ranging from smaller than cherries up to 2 inches in diameter. Crab apples can be golden with a red blush, pink, red, maroon or purplish-red. Some varieties keep their fruit on the tree most of the winter. They produce masses of fragrant white, pink, rose, ruby or magenta blossoms in spring. Many varieties have vibrant leaf colors, from deep maroon to silvery red. Try the variety Dolgo for jelly; Pink Spires for red-tinged leaves, rosy lavender flowers and deep purple-red fruits; or Red Splendor, which keeps its fruits from July through April, unless the birds devour them.
The variety of white mulberry tatarica (Morus alba var tatarica), also known as Russian mulberry, can be grown as a large shrub or trained to a single trunk and shaped into a tree. They produce berries from late June through September, depending on the variety, local climate and the amount of sun or shade it receives. Identical varieties will produce berries weeks later if grown in partial shade, versus those grown in sun. Mulberries produce raspberry-like fruit with a large number of small seeds, each surrounded by a sphere of berry flesh, all stuck together around a core. The core is left on the tree when the fruit is picked and the resulting "berry" is hollow. Birds love mulberries and will eat them to the exclusion of other fruits growing nearby. Plant mulberries as a decoy so the birds leave your cultivated fruits alone.