They don't get the summer heat they need in Britain. The result is that the wood doesn't ripen fully, and isn't strong enough to stay straight in the face of winter storms.

Same with e.g. Pinus taeda in Britain too - look at them in summer-hot eastern US, and they're telegraph-pole-straight, while in Britain, they're rather shapeless, with the trunk not very straight.

Resin

Hi Resin

I was at Bocconoc last year and saw what was a Tsuga
canadensis 80 ft tall or more with a straight trunk.the
needles that run down the middle of the shoots were
upturned and tapered this was a very nice tree.Maybe
they tend to have single trunks here in the SW of
Britian. But it thrives in most parts of Britian.

That's in one of the warmest parts of Britain, so presumably it is just getting enough heat there. Up here, it is a rather shapeless shrubby thing. Interestingly though, it still readily bears cones.

Inadequate heat appears to affect different heat-loving species in different ways, Tsuga grow shrubby but still bear normal cones; Abies (e.g. A. firma, A. holophylla) stay straight and produce cones, but the growth rate is much slower, and the cones produced are less than half the normal size; Keteleeria and Pinus taeda both produce small cones, but they don't mature; Metasequoia grows reasonably well, and straight, but doesn't produce any pollen cones at all; Pinus palustris grows straight, but very slowly, and produces no cones at all; Pinus serotina also has no cones, but grows with reasonable speed except not straight.

Resin

I think Devon could be a good area for Tsugas
but many of these are seedlings and cuttings.
However T diversifolia would struggle here.

I have

T canadensis
T chinensis
T caroliniana
T dumosa
T formosana
T forrestii
T heterophylla
T mertensiana
T sieboldii
T tchekiangensis

Resin, I find it hard to think of Tsuga canadensis as "heat-loving". It establishes in cool forest floor situations, under canopies of northern hardwoods (yellow birch, sugar maple, American beech, black cherry, etc.) where it is densely shaded. If, as you suggest, it needs more heat to harden-off its wood, it would quickly fall to pieces in winter storms, not just suffer a bit of damage.
And the other species you mention, suffering all sorts of maladies, all of which you chalk up to lack of heat --- well, I'd like to see some evidence of such effects. I'd come over to have a look for myself, but the grim landscape you paint of Britain frightens me. I'd better stay in California and bake in the sun.

Ah, but species which need cool summers do so superbly here . . . Picea sitchensis, Tsuga heterophylla, Tsuga mertensiana, Abies delavayi, etc., etc., etc. . . ;-)

{{gwi:689385}}
Tsuga heterophylla

Resin

Hi Resin

All this talk of cool summers sounds off putting average
summers sounds much better. And I think that most of the
worlds conifers like average summers.

Hi Torreya,

They like average for their native locations! And if what Britain has to offer matches that, they do well; if it doesn't, they (by and large) don't.

Resin

And anyway, talk of a cool summer might be very welcome to someone who spends their summers sweltering in 30 degree heat all day for several months!

Resin

Sciadopitys verticillata I thought it liked the western
seabord of Britian through I saw a narrow 60ft tree in
Aberdeenshire.

Resin, you may be right about the "heat requirements" of T. canadensis, but like others here, this marks the first time I've ever heard this tree associated with heat. Here in my home state, it is present naturally in the relatively cool Northeast half, and completely absent in the hotter Southwest.

The natural forest associates of T. canadensis are as stated by Pinetree30, and also include paper birch, Thuja occidentalis, Am. beech, white pine, and a host of other species that comprise the mixed northern hardwoods forest type. Strange and counterintuitive indeed.

+oM

Hi +oM,

Some July mean temperatures (°C; had to go for cities as that's what data is easily available for) . . .

Within the range of Tsuga canadensis
New York 24.9
Minneapolis 22.8
Toronto 21.9
Boston 21.6
Montreal 21.6
Ottawa 20.7
Halifax (Nova Scotia) 18.5

Within the range of T. heterophylla (which does well in UK):
Seattle 18.7
Vancouver 17.7
Anchorage 13.9

UK
London 17.7
Oxford 17.1
Birmingham 16.3
Glasgow 15.1
Edinburgh 14.8
Belfast 14.7

Source: http://www.urbanclimate.net/

Resin

Heh Resin, I was just ask if you had any pics of T. heterophylla growing in the UK. That tree looks better than most growing around town here. Great photo.

Also Resin, do know of any web sites where I can find pics of PACNW native trees growing in the UK? I've heard there's a Douglas fir growing near Archibald Menzie's grave site. Anyways, just thought I'd ask you.
Thanks.

Hi Wadet,

Not that I know of in particular. The UK Forestry Commission has a few on their website, but they're all very small pics. I've put a few on wikimedia commons (that's where that Tsuga het pic is uploaded). I'll make a point of trying to get some more whenever I'm out and about.

Resin

Wow, that pic is amazing, Resin! How old would you say that Tsuga heterophylla is??

My guess would be about 20-ish, maybe up to 25 at the most. It is a self-sown seedling in a conifer plantation; Tsuga heterophylla is locally invasive over here (some parts of the same plantation, there's over a hundred 2m-tall saplings per square metre . . . impenetrably thick!!). The appearance is pretty typical of the species here.

Resin