Whaas, I read this anxiously.

FWIW I had a purple ghost and higasayama acer palmatum which pulled through a cold zone 6 and some form of shrubby laceleaf that predates me living here did as well.

The higasayama does not have its usual attractive foliage. Almost like the buds were damaged. Zone 6 I assume is the lowest it will stand.

Here is a link that might be useful: http://www.botanicalgarden.ubc.ca/forums/forumdisplay.php?f=9

I am 6a. Lost Crimson Queen after a snow then intense heat this Spring after just starting to leaf out. My Fireglow and Emperor did fine and look great. My Summer Gold did great which is still small, but some of the Winter it was under snow cover. At least it was when we had zone 4 weather but wasn't always with the zone 5 weather.

My brother in zone 5b lost Coral Barks but his Garnet and Emperor did great.

Have to replace the Crimson Queen. Can't have anything there too high as it's under power lines and do not want something that could die on me again that I am trying to dig up later.
Cher

A. palmatum 'Beni Kawa', planted 10 years ago close to the western wall of my house. The limbs that were closest to the brickwork on the house leafed out in May and then promptly wilted. The rest of the tree didn't leaf out at all. Lesson learned: red bark JMs are a no go in Zone 5a.

My 5 year old Fireglow, which is planted in a fully exposed location, came through fine, but I wrapped it with burlap,

I am now replacing the Beni Kawa with a Red Baron...and hoping for the best.

Will that is interesting that you say that. My Crimson Queen had the red bark and then my brother's Coral Bark has the orange bark. I wonder if there could be something to that. Know another in zone 5 that Coral Bark is almost bare. I almost bought a new Crimson Queen the other day and thought I better not as it was too much money to just lose again. Trying to decide what to get now that is small and laceleaf that I can find local. Already have a Garnet. Just may have to decide on something all together different.

Glad your Fireglow made it. I love mine. Been here about 6 or 7 years in full sun and does fantastic.
Cher

We just moved to home a little under a mile from Lake Michigan-- very north in zone 5b, within a mile of 5a. Bitter winter to say the least, but the lake did give us a good 7 degree buffer on most days and we have a tall fence to reduce some of the wind.

Late last fall I planted brand new JMs, most of them small and off ebay, and all but the coral bark made it through:

Emperor 1
Fireglow
Corallinum
Seriyu

Absolutely no die-back on any of them. I was astonished. Even the coral bark re-sprouted, so now it's potted and I'm planning on playing with it as a bonsai for however many seasons I can protect it. After reading about all the issues people have had with coral bark in the northern limits, I didn't want to use yard space on it.

Of course now I'm feeling pretty confident, and what was five JMs for our new yard last year has turned into 18 JMs this year... Next year we're going to see if our yard can pull these through:

Tamukeyama
Orangeola (couldn't resist...found it mislabeled at a huge discount)
Moonrise
Beni hoshi
Lemon Lime Lace
Caperci's Dwarf
Umegae
Red Dragon
Tsukushi gata
Scolopendrifolium
Baldsmith
Iijima sunago

Glad to hear about the Korean North Wind. It's one of the ones I've added this year. I couldn't resist that spring color and Iseli claims it's good to -40F.

How do you protect your trees over winter? This year I'd like to wrap them, but I'd love to hear some techniques or advice--

Here are some (crappy phone quality) pics....will be back with more info...

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My fall-planted Acer shirasawanum 'Jordan' did fine for me this winter, a typical snowy winter for here with low temperatures between -15 and -20. What was unusual was that during the coldest temperatures there wasn't enough snow to fully bury it, though the roots were mulched and had snowcover, and it still sailed through with no damage. Whether it will survive the moles tunneling under it now is another question, but I think I caught it in time.

I'm 6a/5b: my 4 year old Acer Japonicum Aconitifolium did not turn a hair this winter. It's in an exposed SW exposure. It's putting on growth like gangbusters. Would not hesitate to try in 5a. 4 might be pushing it.

My Inaba-Shidare, fall planted, also survived very well, no dieback. It was in a protected NE location. I provided no winter protection for either.

Both are in acid clay soil, but both are in raised beds so drainage is good. The soil is lightly amended and fairly poor condition.

This post was edited by robotropolis on Wed, Jun 25, 14 at 9:07

Inaba-Shidare did fine here as well along with Orangeola. Both are under conifer shade.

tj

Here is some info from Brent Markus of Boston. The observations are from Chicago.

The following had zero dieback:
A.p. Baldsmith
A.p. Inabe shidare
A.p. Red Dragon
A.p. Ruby Star
A.p. Trompenburg - this is good into Duluth, MN
A.p. Tsuma gaki
A.p. Twombly's Red Sentinel (this totally surprised me, but they look PERFECT)
A.p. Viridis

A.s. Aureum
A.s. Autumn Moon

A little bit of dieback
A.p. Ueno Yama
A.p. Murasaki kiyohime
A.p. Purple Ghost
A.p. Bloodgood

DEAD or tons of dieback:
A.p. Osakazuki
A.p. Oto hime
A.p. Candy Kitchen
A.p. Ara kawa
A.p. Mikawa yatsubusa
A.p. Ruby Ridge

This is from Diana of Topiary Gardens. She is outside Syracuse, NY...zone 5b.

The ones that had no damage are:
Whitney Red
Mikasayama
Bloodgood
Koto no ito
Chitosayama
Saotome
Otaki
Samidare
Satsuki beni
Saoshika
Red bamboo
Aconitifolium
All shirasawanums
I should just say all Japonicums instead of listing them.
spring delight
tamukeyama
englishtown
a bunch of different disectums

It seems like the reds did better than the greens. The ones listed above were out in the field with the extreme wind and no protection. Maples that were in a more protected area with less wind did fine too but had some branch dieback.

Ones that didn't do well were some of the smaller green leaf varieties (hime type) yellow leaf like katsura, bonfire, shindeshojo type, crinkle leaf type like shishigashira, some of the variegated leaf died back but are not dead. Any of the maples for bark interest died back.

I wonder what makes the red leaves ones generally hardier?

While I am a zone 6a to a zone 7b depending on the crazy weather of the mountains of NC, I have a lot of experience with seeing trees in zone 4 and 5, especially since many of my customers like to push zones. There is a lot to consider when thinking about this topic.

One thing we need to do here is look deep into each tree. When you receive a tree in the mail, or pick out a tree at the garden center, it is important to look and see how hard these trees have been pushed with fertilizers. For many cultivars you call tell this by large amounts of new growth. While this give the tree the appearance of being healthy, these trees that have been over-pushed may not shut completely down during the winter. This makes them more likely to die during the cold spells of zones 5 or a heavy zone 6. My main point here is that we cannot always find an answer based solely on the cultivar. With that being said, the Acer sieboldianum, Acer shirasawanum, and Acer japonicum typically are always great bets for colder zones. Many of our friends in Europe claim that most of the Acer palmatum ssp amoenum group are extremely cold tolerant as well. My girlfriend is at an army base located at the border with North Korea right now in extreme colds and many of the Acer palmatum ssp. amoenum are planted all around her army base, leading me to believe that this assumption is pretty correct.

One thing I have started doing is grafting cultivars like Acer sieboldianum 'Seki no kegon' to Acer sieboldianum rootstock. While Seki no kegon is a newer weeping selection of Acer sieboldianum many graft it to Acer palmatum, thus limiting its cold tolerance. Many claim that Acer sieboldianum itself can handle a zone 3. I have never tested this myself, but I would believe it. By grafting this weeping Acer sieboldianum selection to Acer sieboldianum rootstock we know it will do well in zones 4 and 5 for sure. I have also used Acer sieboldianum for rootstock for Acer pseudosieboldianum ssp. takesimense, which will help keep the cold hardiness in this species as well. This is a practice I hope most start taking with Acer shirasawanum, japonicum, and sieboldianum to keep the cold tolerance of the species within the cultivars.

This post was edited by mrmaple on Tue, Nov 18, 14 at 20:23

Interesting! And common sense, too-- glad to hear someone is doing it the "right" way to help with cold tolerance.