Anyone???

Hard to speak on a zone so cold unless you live there. I have a relative in Montana zone 4 and sour cherry and raspberry work well for him. Huckleberry grow all over there as well as ribes. Hone berry do well in cold climates but many don’t like the taste

Apples will be the easiest. Peaches and apricots will be iffy as they are more likely to be damaged by late spring frosts and need a lot of summer heat to ripen the fruit.

Apricots bloom very early, so flowers or buds can be damaged by frost but worth a try in your zone, not sure about peaches it depends a great deal on local conditions.

So the nursery is selling snake oil? They claim the trees live in Z4 even 3..

I live 1.5 hours from a fruit growing region (We are north of the Niagara Penisula) - while that area is 2 zone warmer, I'm sure something beyond apples will grow here...

Certainly the trees can live.......the question is, will they be productive?

There is more than just an appropriate hardiness zone involved here. I live in one of the largest fruit producing states in the US, yet the areas that produce all that fruit - commercial orchards - have a completely different climate than mine. Mine is 2 full zones higher and yet I and those that live on my side of the state are unable to grow the same fruit with the same degree of success. And that is because our climate - not just in winter but year round - is so different from that of the commercial fruit growing areas. I live in almost a zone 9 climate and yet peaches are very tricky to grow here and apricots are pretty much a complete no-go!!

In the US, we have agricultural extension service offices in each state (actually every county) that assist home gardeners, home orchardists and home farmers with the most appropriate plants to grow in their area for the most successful production. They have listings of specific fruit varieties - by area - that are known to work well and be productive in that area. Do you have a resource available like that? That would be my first area of research....just don't rely on the nurseries. They are governed by a profit motive first so confirm their choices or selections elsewhere before proceeding.

As stated, both peaches and apricots (and hybrids involving either of those two), bloom very early in the year and so are far more prone to the buds and flowers being damaged by spring frosts. No flowers = no fruit. The trees will live and grow....they will just not be very productive. And if they manage to miss any spring frosts, they need a period of sustained heat in summer for the fruit to ripen successfully.

Besides apples, other fruit trees that can thrive and be productive in colder climates are pears, sour cherries and some plums. All are likely to be more productive than apricots or peaches.

You asked for the 'easiest'....and you got an answer :-) How much harder you want to work to generate a crop is up to you.

Apples are the most likely for your climate. There HAVE been some newer super hardy varieties out of the breeding program at U of Saskatchewan. The Wowza! cherry is hardy to zone 2, as are their Romeo and Juliet. Carmine Jewel down to zone 3.

Peaches are a struggle, even in zone 5. Michigan State shut down their peach breeding program that produced the Red Haven and other cold hardy selections. I don't think anybody has really been working too hard to push the envelope, since.

This is a good book to have, if you want to start a home orchard:

https://www.amazon.ca/Growing-Fruit-Northern-Gardens-Williams/dp/1550509136

ETA: Michigan State did NOT shut down their peach breeding program, but instead partnered with some private growers. Things have been quiet, but there is still activity on that front. This has included development of the Flamin' Fury series, as well as the Stellar Series. I wouldn't be too surprised to see an occasional new release, since there are apparently a few varieties currently in test plots.

Zone 4 Central MN. started a mixed fruit orchard 11 years ago. steep learning curve! I have found cherry and plums to be the easiest to grow. No real problem with parasites or fungus; main problem is birds. Apples grow well but have a wide variety of pests to deal with. Pears have been ok after a slow start; I'm on my 3rd attempt to grow peaches and apricots rated for my zone. I strongly suggest you buy your trees from a nursery, the typical retail outlet doesn't specify the rootstock which is a critically important variable. buy trees from a nursery in your same zone, the only significant failure I had with nursery trees was trees bought from a nursery in a warmer clime even though the trees were rated for my zone.

I'd add saskatoon/serviceberry to the list as something that will almost certainly produce in your area, but it looks as if you are searching for a variety of peach or stonefruit rather than just a general fruit tree. My folks garden in z4 MI and are really only able to get apples and strawberries reliably. The wild blueberries up there fruit about every 2-3 years though.

thank you all...