Strawberries- you can get some of the alpine, woodland, and musk. I’m not sure if you grow any of those already. My wife thinks the regular “hybrid” strawberries are better though.
Arctic kiwi- grows well here. Don’t waste your time with hardy kiwi. OGW just released a new batch of named cultivars and some look interesting.
I tried an asiatic cornelian cherry in Canada and it was pretty good. It is supposed to be cold hardy but you can’t find it anywhere (Cornus officinalis). I think some varieties of the regular Cornelian cherry (Cornus mas) are easily purchased and could be zone 4 hardy.
Mountain ash- grows all over town. The berries are not good to eat, but apparently they can be turned into a jam. @steveb4 grafts a pear to a mountain ash.
Illinois everbearing mulberry is said to be cold hardy to zone 4. Plenty of zone 4 hardy blueberries (although you may need to amend your soil to be more acidic). Cranberries. Huckleberries.
Ground cherries, although they are annuals they often self seed even in very cold regions. I highly recommend an early cultivar if you’re interested in them.
Also i know you mentioned currants, but there is one variety called a crandall currant (ribes odoratum). Its as different to regular white/red/black currants as regular currants are to gooseberries. In addition, they’re extremely productive and shade tolerant. Mine only get 3-4 hours of sun max and they’re pumping out hundreds of berries.
I can assure you IL Everbearing mulberry is not hardy to my location in 4a.
Darrow blackberry roots survive winters, but the tops die back completely. In years where we have a long growing season they will bloom and set fruit, but the fruit rarely ripens before a hard frost hits.
Have you tried Trader Mulberry from that 100+ y/o tree in Oriska, ND? I have 2 small ones here in air pots that I plan to plant either next year or the year after…once the roots system gets very fibrous.
Back to the OP, they’re hard to grow, but if you’re in a moist zone 4 maybe you could grow some cloudberries?
No pears? I just added 1, waiting on 2 more. Just curious, zone 4 - how do your cherries look this year? I am in 4b in MN, have romance series and the CJ are tiny. trying to figure out what to do with them as they are ripening - they might be too small to pit, but flavorful.
Pears could be a must. I like a good pear as much as I like a good apple. Wintergreen is a berry ground cover that is hardy to zone 3. A lot of uses for it like mint tea from the leaves and it has a edible berry. It spreads through rhizome so easy to get more as well. Arctic raspberry is a thing that will spread by rhizome too. Kirsten sweet cherry is hardy to zone 4.
Yep, I have two Traders. Planted in September of 2015. They survive winters just fine. The problem is the fruits are less than half the size of the last segment on my pinky finger.
That’s kind of a bummer. How large are your trees? I was planning to prune them heavily in my chicken run and (try to) keep them under 10ft. My chickens probably won’t mind the small berries. I have an IE that’s going out in the front yard to grow as large as it pleases.
Seems like you have most of the usual suspects covered.
Some varieties of highbush cranberry can be tasty, but make sure you get the American variety if you are planning to eat it: Highbush Cranberry.
Maybe you’d get lucky with an peach, apricot, or pawpaw and occasionally get fruit? As others have mentioned, there are some pears that should work.
You might be underestimating the difference between wild and cultivated blueberries. Wild are fantastic for flavor, but domesticated have some different but good flavors, as well as being much larger fruit.
Growing Fruit in Northern Gardens might be a useful book, but I think you already have most of their suggestions. Bob Bors, one of the developers of the USask bush cherries is one of the co-authors.
fedco sells quite a few z3 hardy pears. i have 4 of them growing on my 7ft. mountain ash. think they are nova, patten, summer crisp and stacyville. also ivans beauty/ belle are Russian developed hybrids of mountain ash/ aronia and mountain ash/hawthorn and also Rabina and shipova pear. onegreenworld.com sells them. i have the Ivans beauty in 2nd leaf. its a vigorous grower here.
For starters our short season means that there are all sorts of hardy plants that can happily grow here but that will never have enough time to ripen fruit.
Then there is the January meltdown we often get, a week or so in the 40’s and 50’s that can be followed by temps going sub zero the next day. Anything that gets fooled into waking up dies right then and there.
Some plants time dormancy based on light signals, which here they don’t get until it is too late. Heck hops won’t flower until the days get short enough, which is what we call winter.
I have two franklin cider apple trees I have been testing. They are super hardy, don’t wake up during the January meltdown, wake up early, blooms are super resistant to late frosts, and are growing vigorously. Having said all that I may end up pulling them because the fruit simply will not reopen on time, it is still green by the time winter sets in