There has been a new plum tree called BlackIce developed by the UW-River Falls that is supposed to be as good as the California plums. This year it is now available to the public and can be purchased from Jungs Nursery. I have ordered one, since I only live 15 miles from River Falls, so assume it would do well here. Also the new honeyberries known as haskaps that have been developed in Saskatchewan are available in the U.S. for the first time this year. See my post from a few days back. They are supposed to be much better than the honeyberries previously available in the U.S. There are also some bush cherries known as the Romance Series developed at Saskatchewan that are highly touted. Only Carmen Jewel is available in the U.S. so far; and St.Lawrence Nursery in Potsdam, New York, had Crimson Passion for a couple years, but no longer. I am hoping more of the half dozen varieties available only in Canada will soon be available here. These should all be quite hardy where you are; and the honeyberries and bush cherries are supposed to be fairly low maintenance. New introductions don't always pan out to what they are cracked up to be, but the Canadian gardeners have given them good reviews on the forums. The haskaps would ripen at a time before most other fruits, which is another bonus, and when the other bush cherries become available, they have staggered ripening times for different varieties, too. You won't want to be tied down to an extensive spraying program and spending your whole time canning and freezing when you retire, so with low maintenance items, if you are gone on a trip or experiencing health problems, you can just tell a friend or relative to pick the fruit, but they won't care to do any spraying, pruning, or weeding. Also, with bushes you won't have to contend with ladders when you are old and your knees get decrepit. I can't imagine how retirees could eat 50 trees worth of apples, either, unless you will have lots of grandkids around or plan to sell them. I would go for zone 3 blueberries if I were you, like Chippewa, Polaris, or St. Cloud. That is smart of you to prepare the soil in advance. There are pears that should grow fine where you are, too, but it can be a long wait for the tree to mature. I have Summercrisp, Flemish Beauty, Clapp's Favorite, and Luscious, but none have fruited yet. Summercrisp is supposed to be entirely free of fireblight, very early, and quite hardy. I am also growing lingonberries, as they are very good for you, plus are a nice ground cover and can take a little afternoon shade. Your van cherries might be questionable. You might even be on the fringe of where montmorency will fruit consistently. If I were you, I would try just one of each to start with. I have a Lapins going on its third year now and figure if I get fruit even every third year I will be thrilled. Have also ordered a Kristin, which is supposedly hardier than the other varieties of sweet cherries. Also, avoid dwarf trees this far north, as they aren't as hardy. Semidwarf is okay for apples, but otherwise standard are recommended. With all the space you have, you might experiment with a couple apricots. Westcot, Jerseycot (if you can find one), Sugar Pearl might fruit for you at least some years. And of couse, there are the old standbys of strawberries and raspberries, which will give you fruit the first year. Don't forget to fence against the deer and rabbits, and net against the birds, which can cost more than purchasing the trees. Best wishes with your fruit adventures.
Northwoodswis

There should be a number of pears that would do well for you. Northwoodswis mentions some of the ones that should do well. You could check out the offerings of St. Lawrence Nursery and Fedco as they specialize in trees for colder climates.

If you try another pie cherry, I would suggest an Evans, which is sold by St. Lawrence under the name Bali. It is a very hardy tree which is supposed to be a natural dwarf. I planted one about 7 years or so ago and it is still a small tree for me (about 7' tall now) and produces LOADS of very large cherries. Last year I havested about 25 lbs. off the tree. It ripens late (mid August for me while Early Richmond ripens in early July), and is best if left on the tree for a couple weeks after it turns red. For me, it has an astringency when first red that goes away after a couple weeks. I have to net to keep the birds away. One tip from my northern Saskatchewan relatives with one--let the soil dry out in September to encourage dormancy as it can be a little slow to harden off for winter if moisture is plentiful. Growing grass right up around it can help with drying the soil out. Mine has never had any winter problems, though it is on a drouthy site which may also have helped retard size.

You could also look into some saskatoons, often called Service Berries or June berries around here. They are similar to blueberries but don't require the low pH.

The Univ. of Minn. has developed quite a few varieties of different fruits which should do well for you, and there are some hardier grapes for your area too. Also consider chokecherries and buffalo berries, both of which make great jellies.

There are also american/european cross hazelnuts which may do well for you. Badgersett would be a local source for you, they are located south of Rochester not too far north of the Iowa border.