These are all valid questions and I eagerly await the responses from the pros. The most unanswered question for me along these lines has always been whether the hardiness refers to the roots or the buds...or both...or roots on this one, but buds on that one.

My assumptions to your questions:

1. Only P. sylvetris root problems would be a concern
2. Don't know-root hardiness thing.
3. You are correct.
4. A bud hardiness issue.
5. I'll leave to grafters.

tj

1. P. sylvestris is very tolerant as a root system but there lies the problem with the foliage susceptibility to pathogens and or/wood/buds, etc-. P.sylvestris will not halter the scion of heldreichii in any way. You need to remember that climates are for both the root systems and then separately: the leaf's, buds, wood. Therefore where where "a" may be conducive to climate "a" it's other half may not be conducive to the same, climate "a".

2. Generally speaking hardiness is 'rated' for bud or leaf, however, roots will apply also. Same type of analogy as I just described using "a" to represent two things at one time.

While Abies procera is pretty well a zone 6 hardwood: buds/foliage - I do not have the data to tell you the rating of the roots but, more often than not the roots should be presumed to be of similar hardiness (generally speaking, and I'm just being general).

3. Yes, you are correct. I agree with TJ. Being a grafter I know that Picea pungens is very sharp to work with removing the needles on my understocks, whereas Picea abies is not painful or difficult. Plus, Picea abies can be grown to live just as long as Picea pungens even in pungens natural range. I'd say that to be quite true. Again, I don't have the data, but Picea abies is so adaptable.

4. Pinus thunbergii is purposely used for bonsai, however, the same would apply to landscape plants. Furthermore, again, Pinus thunbergii: buds/foliage are zone 6 hardy and I don't have the data to tell you if the roots are any hardier.

If parviflora is grafted to strobus, parviflora can only withstand (again) bud/leaf tolerances to frost. TJ is correct.

5. Yes, you can expect in the USA: Picea abies; for firs two are used: nordmanniana and x phanerolepis; hard pines: sylvestris is used; soft pines: strobus. There really isn't much deviation at all from this because that's what the market is selling us.

Dax

5. I missed pungens; and sure they're selling Abies firma also, but only nurseries playing the smart card are grafting onto firma with similar firs that will withstand heat.

Europeans have better seedling nursery resources and for firs they use Abies koreana x lasiocarpa and then veitchii as the second choice. The hybrid has it all. Plenty of speed and cold-hardiness plus adaptibility to many soil types. And for the firs that may need increased cold-hardiness and/or more speed, then they use veitchii. Promoting that in the USA would scare off grafters, but in reality it's the grafters that are missing the eight ball.

Pinus armandii (hardy seed origin) is used extensively throughout Europe as is wallichiana. Both of those survive better in greenhouse conditions than strobus. Again, the Europeans are ahead of the curve/game.

For dwarf hard pines, Europeans purchase Pinus pseudopumilio and sylvestris as the second choice. P. pseudopumillio contains the genes of the wet land "mugos" and the genes of the dryer alps "mugos". Again, superior.

Dax

Awesome, appreciate the input guys!

This got me thinking about this in your reply about me selecting a plant that is saline soil tolerant.

I found this one before this post...here

Then I stumbled across this...one

Strange that it didn't have more activity.

Dax, I was probably trigger happy with my last post.

Regarding Abines nordmanniana and x phanerolepis as the 'typical' rootstock for Abies.

Am I correct to assume that the drought tolerant Abies concolor cultivars I thought I was planting are in reality (likely) drought intolerant Abies nordmanniana and Abies balsamea var. phanerolepis rootstocks?

Whaas, great questions. I'm so glad you asked here on the forum. The information given is very good and will be helpful to me as well.

Whaas, your assumptions that nordmanniana and x phanerolepis are drought-intolerant have no value.

Best Regards,

Dax

Hey Dax,

I apologize but I don't understand your post.

Are you saying Abies balsamea var. phanerolepis and Abies nordmanniana are drought tolerant?

Or that its relative to zone/climate/other rootstocks and therefore my comment is too general?

Will,

I think it's best to consider the needs of the roots and tops of the plant separately. The USDA zone rating is a rough geuss but as you know, with so many other factors coming into play as well (wind, wet soil, on and on...)

Here's an interesting example from the same webpage you quoted from above:

"Cedrus atlantica, brevifolia, and libani are all grafted onto Cedrus deodara, the least hardy of the three. There are several reasons for this choice. The hardiness is not a factor since the deodara root system in the ground is at least as hardy as any Cedrus cultivar above ground. Secondly, the root system is more fibrous and better developed than in the other species making it a much better choice for nursery use."

In this example, the top is least hardy, but the roots are most hardy, and the species is the preferred understock.

I geuss this all gets at your fourth question to illustrate that you cannot make a plant "more hardy" by choice of rootstock, unless the limiting factor is the hardiness of the roots (not the top) in the first place.

I geuss others already made this point more concisely - just wanted to add my two cents and what I thought was an interesting and illuminating example.

Alex

I should add that the roots are not actually hardier than the top. It is the fact that the ground temperature is not subject to sudden changes up and down and stays warmer than the air temperature during extreme cold.

Roots in exposed containers have about the same hardiness (even less in some cases (Acer palmatum)) as the stems and foliage. Plants grafted onto less hardy understock and being grown in containers need winter protection or the roots can die.

Bob

On Bob's note....

In theory from a temperature perspective, the buds will generally fail before the roots?

If that is the case I don't understand why folks are concerned about having mulch and snow to protect the roots from cold. If the plant above ground is exposed to colder air temps then the buds would fail first.
Of course this woudn't apply to smaller plants that can be completely covered by snow.

^^^ No, the temp at which buds would be damaged is by no means the same as the temp at which roots would be. So a plant could be sufficiently "top-hardy" to withstand a given temp. but if, for some reason, whether lack of snow or other, the roots freeze harder than they're able to withstand, damage will result.

I don't think I explained that all that well. The fallacy of what you are proposing, er, asking, lies in the incorrect assumption that buds and roots are both affected by the same temp. Did that help?

;^)

+oM

Tom's answer may have geographical origins. It's a tough one to break apart.

When scientists test bud/needle hardiness they expose them to frost and then biopsy the results.

Regarding his answer, there would have to be a scenario where the ground was colder than the ambient air temps. And only geographically can I look to find an answer to explain this, where:

(heavy snow cover vs. none and an extreme fluctuation in weather, probably drawn out slowly over several days or a weeks time -- where frost doesn't occur on the buds/needles and at a place likely where no moisture is in the air -- for this drawn out period of time)

Hopefully someone smarter than I will weigh in because I can't explain it very well, either. This could all just be theory too.

Dax

I think if 8 or 10 more of us answer this we ought to nail it by then...

Maybe its just a semantics thing, but I have to disagree with Bob that roots in exposed containers have about the same hardiness as the foliage. Here in zone 5 and colder we are always cautioned that if's going to over-winter outside in a container, a plant better be at least one or even two zones hardier than where you are. Not because of temp fluctuation but actual cold temps.

Dax, I don't think +om was talking about roots being colder than the buds, just colder than the roots normally would be (no snow cover or whatever). In the ground they will almost always be warmer than the buds.

For instance...

Lets say a tree is hardy to -30. It's roots, being in the ground, never see, oh lets pick a number like -10. Now along come a spring flood that washes all the duff, debris, and perhaps a bit of the soil away. The next winter has a stretch of -30 and, dang, no snow either. Now the roots are -20 and cells explode. Buds were fine, roots died.

tj