Zone 4 Woody Ornamental Trials 11 years later-big surprises(pics)

17 years ago

I was walking through the South Dakota arboretum (Z4a) in a area off the trails and I found the trial area. I had my camera for fall pictures.. and I wandered into the old trial grounds. An internet search reveals most of the plants that were trialed. I was shocked to see how well some things were doing, that common knowledge says that they should be dead many times overÂ

So here are the plants that were planted in 1996 for trialsÂ

The most noticeable plant that I saw was this birch, that I later found out to be Betula platyphylla 'Fargo' (trademarked name Dakota Pinnacle)

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"It grows from 12 to 15 meters tall under cultivation, and is known for its almost pure white, exfoliating bark. The accession is a clonal selection having a pyramidal-columnar habit, dense canopy, dark green foliage, and manicured appearance. The clone also is noted for its cold hardiness, drought tolerance, and relatively rapid growth. This accession may be worthwhile to test for birch borer resistance in those areas where borers limit the use of white-barked birches. The species offered has a wide native distribution over China, the Korean peninsula, and Japan."

It was obviously not resistant to borer, however. Of the atleast 3 trees planted, only 1 survived.

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I was then shocked to see a plant that is supposed to only be hardy to zone 6- Chinese wingnut

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There are 3 trees, 20 feet tall, no dieback apparent on the branches. This tree is obviously much more cold hardy than assumed.

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Physocarpus ribesifolius Â this is the plant I got most excited about. ItÂs a standout now with interesting seedheads on the branches, and obvious evidence of very profuse blooming this year. [Continued on next post]

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Comments (8)

Fledgeling_
Original Author
17 years ago
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Found under the Physocarpus ribesifolius was Spiraea miyabei Â apparently this plant was expected to be a dieback shrub past zone 6- not so! It is alive and well, has new growth from old wood, and the corymbs were huge. I would like to see this during the growing season.
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The grey shrub behind the birch in the first pic is Forestiera neomexicana 'Jemez'. Its branches were very tall and dense, with an attractive winter formÂ since it was leafless that all I can say. Looks like it would be a good hedge plant.

Apparently only Physocarpus ribesifolius was thought to be hardy in zone 4 before.

What im trying to show by all this is that zone pushing can be very fruitfull. DonÂt be out by plants that are not ÂsupposedÂ to be hardy in your area. You might be surprised... i was!!
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cacau
17 years ago
Interesting to see these results. I'm now much less concerned about the viability of the Wingnut (hybrid) we have here. Someone has to try plants out of zone from time to time. How else did we learn about the hardiness of Osage Orange, Baldcypress, etc. being greater than where they grew natively? This could be especially true for plants native to Asia that are relatively new on this continent.

One I've got growing here in containers is Leitneria floridana, with plans to set it out in a year or two (not really a huge risk since many references call it Zone 5). The ones I'm concerned with getting nailed by an unusually cold winter are Nyssa sinensis, Chionanthus retusis, Acer macrophyllum, Magnolia sieboldii and Cedrus deodara. There'll always be losses from one thing or another, it's part of the experience (not part of the fun, though).

Cacau
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conifers
17 years ago
Cacau,

I lived temporarily in zone 5 Indiana in Bloomington and they had success for only two or three winters with Cedrus deodara. The needles would fall off and/or turn brown but the tree would re-foliate each spring. Then whammo - that was all over with. Cedrus libani subsp. stenocoma will be hardy however. The only true Cedar that will be hardy for you.

Good luck with the others. Dax
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cacau
17 years ago
Dax,

Did they (or you) have the cultivar 'Shalimar' that is supposed to be hardier? The one here is a 'Pendula' and has been through 3 winters with a minimum -10 F. So far it's never browned or lost any needles, and it produced cones this summer. I'm sure its favorable location helps--it's about fifteen feet south of a south-facing three-story stone building, and the ground also slopes off fairly steeply to the south for good air drainage.

Yes, the C. libani usually grows fairly well here. The C. atlantica is viable, according to some local nursery folks, provided it's given some protection, but I haven't tried it.

Cacau
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laceyvail 6A, WV
17 years ago
I bought a Spirea miyabei several years ago from Roslyn Gardens (sadly missed nursery), but I've not been able to find out anything about it. Can someone here tell me about its pruning needs? It's done very well here.
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leftwood
17 years ago
Leitneria floridana has been hardy through 2 winters for me here in z4a. The first winter was wimpy, but last winter got down below -25F, although not for a long period as it normally would. No flowers buds priduced yet.

Mag. sieboldii is hit or miss here, depending on the seed source, but I have had one since 1995, and it blooms and fruits regularly. Others that are long time successes here are:
Acer mayabei
Aralia elata
Calycanthus floridulus
Calycanthus fertilis
Carya illinoiensis(very northern seed, no flowering yet)
Cercidiphylum japonicum
Chamaecyparis pisifera types
Cornus mas
Corylus colurna
Cotinus obovatus
Diospyros virginiana 'Meader'
Euodia danielii
Fagus grandiflora
Forsythia mandshurica 'Vermont Sun'
Ilex x meserve 'Blue Boy', 'Blue Girl'
Liriodendron tulipifera
Picea asperata
Picea crassifolia
Styrax americanus(kankakee seed)
Thuja koraiensis
Thuja plicata 'Cuprea'
Viburnum carlesii
Viburnum x 'Juddii'
Xanthoceras sorbifolia
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cacau
17 years ago
Leftwood, how much suckering are you seeing on that Corkwood? How far from the main stem? One of mine already has sent up a sucker, via underground runner, at the edge of the container 6" from the main stem.
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kman04
17 years ago
If it helps, my Florida Corkwood has suckered as far away as about 20' from the original planting, but it's been in the ground for nearly 15 years now. It mostly suckers within about 10' from the original planting.
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