I see winter damage to our blueberry shrubs from browsing rabbits, but very rarely do I see a branch die back due to cold winter weather. Our soil is heavy clay, and I amend the soil with peat moss where the blueberry shrubs are planted. The clay does tend to hold a lot of moisture which is slowly released as the plant takes it up, until the ground freezes. Our blueberries are also mulched with wood chips, and I am seeing mushrooms growing nearby so I know there is moisture present. If you have well-drained sandy soil, I can see where keeping the blueberry shrubs hydrated could be an issue. I can't think of any simple solution, however.

I am probably very close to you. Are you by chance on lake superior, or inland? This makes a massive difference up here. What exactly are you growing as well?

Something here usually gets tip dieback, but some species its expected. My one rose, "the hunter" is hardy to -35C, yet even in winters with temps no where near that, they get some dieback on the tips. Roses just seem to have some branches that die back a bit **the reason will be answered in a minute***

Evans cherry seems to routinely die back a bit in zone 3. You can expect some die back on some of the U of Sask cherries as well.

My "john" pear and Honeygold apple had no die back last winter, and im sure you had a similar winter as me.... it was horrible to say the least. My toka plum had no tip dieback either.

Either way, the windchills, which doesnt effect plants like it does us, will dry out plants, even if they are "hardy", and even some native trees will do the same if too exposed or us having a bad winter. THis can be caused by late season growth, due to a weird year, late fertilizing or over fertilizing in spring (too much green growth. Green wood in winter will usually die back I think).

2) You want to stop watering in late august or mid september. It really depends on how long the season is and seems to be. Even here, our "expected" first frost is september 12, but more like beginning or middle of october. Either way you want to slow watering about 6 weeks before your last expected frost date, and stop I think a month or so before (double check that to be sure). THis forces the trees to shut down slow, which can make or break your success. The slower the dormancy, the better the hardiness potential.

I am also assuming you get deep snow like up here. That can make a big difference in dieback of lower plants. Using deep mulches has allowed me to grow bamboo 4 years running, and the 2 that have survived have never died back because i bend them to the ground, and bury them in 2 feet of leaves. I do this to my "stevens" crannberry, rhododendrons, grapes, roses, herbs and around the roots of my trees.

If the shrub looses its leaves during the winters, mulch when the leaves drop. IF it is Evergreen, mulch when frosts are deep and persistant ( I mulch my bamboos when the nights are lower then -10C and we get the bad windchills. Roughly late october or mid november). If it is a herbaceous plant (lets say, parsley or asperigus), then mulch when it dies back. In the case of vines, some you may want to wrap, some you may want to detach from its support and lay it on the ground and again, mulch.

All else fails, it should be done before your first deep snowfall. Mulch and snow is a big winner here.

My latest "cant grow here" project? Musa Basjoo. That is the hardy japanese fiber banana. This guy is getting cut down, and being wrapped in a mulch cage, wrapped in a tarp and snowed in.

I'm located about 100 miles straight west of Duluth (southern tip of Lake Superior). None of my fruit trees or cherry bushes have had a problem with any winter "die-back" in the last couple of years. I don't fertilize past the end of June and I do start cutting back on adding any water about Sept 1st. This has helped with hardening of in the past. My fear was the defoliation from the deer would act like a late fertilizer, causing new growth late in the season.

It has only been my blueberries and raspberries that have had a die-back problem every winter. We do have sandy soil that drains fast, but I added a large amount of peat and rotted sawdust to the planting holes in the beginning, to help with moisture retention. Maybe that is keeping them too moist to harden off properly?

The varieties of Blues are some of the hardiest, and the raspberry is Boyne.... a good zone 3 berry.

Maybe we will have a mild winter with lots of snowfall. That would help a lot.