Yes, A. palmatum and friends are prone to spring frost injury. Laceleaf cultivars may be burnt even here in USDA 8. Sheltered positions are recommended just because of this problem. Many other popular garden plants of East Asian origin, that become active early in the year are also liable to be frosted - camellias and early-blooming rhododendrons, for instance.

Also meant to add that the triflorum group all seemed to recover pretty well. All lost their foliage, but the A. griseum, triflorum, henryii, and cissifolium plants I've seen came along pretty well.

A. carpinifolium came through the freeze okay, but the drought really hammered it.

Scott

We were lucky in the quad cities region of Iowa/Illinois (Rock Island, Moline IL - Davenport IA, Bettendorf IA)
The leaves were only beginning to show and the weather warmed up here otherwise it could have been as bad as those including folks in zone 7 New Jersey, etc who had many plants both killed, and damaged. It was definitely area/region of the country 'specific' for me. My Seiryu I don't believe was even leafing. No damage at all. My Acer japonicum 'Acontifolium' had leaf clusters showing at least 1/2 way from buds opening and pretty much the same as for my Seiryu. I might have had one or two days that worried me. Acer griseum broke bud later than all these and was not phased.

There was actually a ton of discussion already here at this forum during spring. A poster here with a vast collection in zone 6 Illinois upon my request noted the following:

"David From N. Illinois (Sept. 2007):

I was hoping to this spring but the freeze screwed me up it will have to wait a bit...I can only say the ones i would not plant again but even those I might plant in a better spot ( IE: Japanese Sunrise ...the best of the winter color trees IMHO )in the same place ..i think in the right location most any A.P will do ok here ...but it seems more important which ones are the hardiest no matter where they are sited we all don't havbe "perfect spots for them. Also most of mine did survive the freeze but were damaged I really want to see how they do over this winter in their non perfect shape...then , as long as it isn't a extreemly mild winter I will post. As far as last springs conditions some seem to do ok or basically untouchedeven with the freeze but many were covered part or all of the time ...so any comments would seem presumptious. These " seem to be the hardiest Red Baron, Bloodgood, Atropurpureum, Beni otaki. Sclopendrifolium,Scolopedrifolum Rubum ,Koto ito kamachi,Kasagiyama, Berrima Bridge,Musashino,Atrolinear,Fire Glow Emporer 1 ( ???one made it one id just barely holding on 1/20th it's original size, Red spider web, Aka shiragasa sawa, Pendulum Julian,Yubae,Red Dragon ( one made 1 didn't) ,Van de akker,Oridono nishiki, Nishiki gasame, Beni Kamachi, Goshiki shidare, Tamukeyama, Emerald lace, Ukigumo... Remember most of these were covered at least soome of the two week freeze period!!!
many others like Shojo mumura and Inaba shidare,Sumi nigashi , Orange Dream, Hupps Darf , Sharps Pigmy,Octopus,Edgdgewood Golden , Omurayama, Raraflora, Coonara Pigmy and many many others survived but I will not say "thrived" Time will tell.
As I said this is NOT a good test since in reality most seemed to be fine before the freeze after a rather severe winter with lots of differnt hazzards ...but that was only for about 2 weeks before the freeze!! D"

Nice to see you Scott!

Dax

Central Illinois
Getting ready for the coming winter, I was looking for tips (you never know what you can pick up...amazing).

My report- The Japanese maples that had leafed out all new growth died, but sent out new growth so that you could hardly tell anything happened. There was no seed production this year. The one that looked the worst was A.p. 'Kamagata' because it was fully leafed out. It survived okay, but doesn't look as nice due to all the dead I had to cut out. I'll be curious to see what it looks like next year. I did not lose any due to the freeze, which for me was over a week of 20 plus or minus a degree or two. The trees I have are: Garnet, Crimson Queen, EverRed, Usigumo, Beni Shishihenge, Beni Otaki (2), Beni Shishigashira, Osakazuki, Waterfall, Butterfly (2), Orido Nishiki, Pixie, Trompenburg, Virdis (2), Atropurpureum, Filigree (2), Iijima sunago, Grandma and Sister Ghost, and probably a couple others that I've missed. As far as others, I didn't lose any campestres or circinatums, My A. shirasawanum 'Aurea' had tons of seed, but it was small and distorted looking, so I don't know if it will germinate. My japonicums did fine. Griseum did fine.

Question: Do any of the Moline and Chicago people ever play "Show me your maples and I'll show you mine?" I want to see your maples. Dax, your listing of Japanese maples growing in Northern Illinois is staggering. I am in the Peoria, Illinois area, so if that's a possibility...
Kay

Yes we went through this matter last spring... It made a really BIG differnce where you lived even in Peorea 60 or st louis 90 miles south of here miles... north it was not as bad south it was worse Chicago was untouched!!.... and couple this with the heavey 1-2" rains that came right after( HERE) with ground totally frozen it was not pretty here . Yes most shot out seconday leaves but for the most part it was bark damage not leaf damage that did them in...along with psuedonomous and other stuff that attacked weakened trees.
I think NOW any complilation of winter hardiness based on last years freeze, as alluded to in my spring post, is basically worthless . This was a 50 year condition and IMHO not really applicable to winter hardiness...and as I said we had a hard winter cold temps down to -15 to -18 lots of snow two really bad ice storms yatayataya and ALL came through fine til that unusual situation .... Add to this identical culivars planted within 10 feet of one another same age and size and one making it fine and another NOT ...it would seem many factors came into play here and do in any situation as far as hardiness.

If we learned anything the plants that wake up and leaf out early will be the least hardy since the sap is running and suseptable to both leaf and more importantly bark damage!!! and those that have luck with those culivars are the exception... Also if you really want to be safe containerize your trees. I will aslo say the red barked cultivars "seem" more hardy in general than their green cousins even though most root stock is A.P.Green Acer Palmatum... the red bark is a bit harder and seems thicker...or maybe its becuse of their heritage ...but that is my one obsevation that I will stick with anong with the two above. David

I am not sure either as to what information we can take from this springs weather as to cultivar hardiness. I have Takesimense here and it came through OK while Scotts didn't and we both live in the same area. I think it was more a factor of how much sap was in the bark and leaves. As a general note my Shirasawanums pushed later than either my Japonicums, palmatums or sieboldianums and therefore did the best.

Now that the leaves have dropped I can tell that most of my twiggy palmatums have lots of dead wood in them. The plants with thicker stems seem to have done better. Older, larger caliper plants also have less overall damage.

One other note on this topic is that we should wait and see how plants do next year before making any determinations. Some plant may not show the full extent of the damage until next spring.

David

Ditto to everything said. It'll be interesting for me because eventually I'm planting a seedling grown collection for the most part. It'll be a long 10 years before I know anything however as I'm in my second year only for seedlings. One more summer of grafting in 2008 and I'm done growing cultivars.

Good luck everyone!

Dax