Jeff Layman wrote:
Emery Davis wrote:
Jeff Layman wrote:

But where did the statement about ericaceous compost come from? According
to the RHS Dictionary of Gardening, "Most species prefer a
neutral to slightly acid soil". None of the books I have make any
reference to not using straight ericaceous compost.

"neutral to slightly acid" is standard for A. palmatum, as cited from
Vertrees 3rd ed.
"Japanese Maples." I think the issue is that most ericaceous (my
spelling error earlier)
compost one buys has too low a pH. (Tried to find rapidly the "ideal"
pH for palmatum
but didn't see it.) I know of no serious collector who uses straight
ericaceous compost.

See for example here
http://www.bbc.co.uk/gardening/plant...ges/1579.shtml
(and other pages with a google search on "acer" and "ericaceous
compost").
Just FYI, this page tells us that we can plant this maple on
chalky/alkaline soil.

Yes, it is a bit too universal! I was referring to the text below the photo
"It makes an excellent plant for a container, filled with ericaceous
compost."

Not impossible but it would require a very green finger indeed to get
it to grow. Also
so to not get kicked out of the Society I am honour bound to mention
that there
is no Atropurpureum group, nor is this a proper cultivar. What's
found on the market
under this designation is a grex at best, but more likely seed grown
plants of uncertain
habit and vigour.

You are probably correct, but it's in the RHS "Plantfinder" (under the same
name as the BBC webpage), which adds "tentatively accepted name in the RHS
Horticultural Database".


That's probably where the beeb got it from. Surprising that the RHS has
it that way
especially as most of the Maple Society officers figure in the ranks there.

FWIW, I have grown A. palmatum "shindeshojo" in ericaceous compost
for 7 years. It continues to do well, and IMHO is still the best
red-leaved palmatum cultivar around.

I'm glad your plant is doing well and that you enjoy it. I suspect
the compost is
not so acid anymore unless you amend it.

Shin deshojo is a gorgeous maple in spring but is not known for
holding it's colour
well into summer. For that reason Vertrees lists it as group 1a,
(palmatum/upright/green),
and while van Gelderen et al put it in 1b (red) they mention that the
leaves fade to
dark green in summer. Although I don't yet grow this one I do the
original Deshojo (shin
simply means "new" in Japanese) and am very impressed by how well it
holds its colour.
Since mislabeling is endemic with maples, if yours stays a good red
all summer I'd wonder
if it is really who it purports to be!


It does fade to a pinky green in summer (although last year's summer was so
bad it kept its colour well for much longer). But then turns a superb red
in autumn. So when in leaf it is red for much longer than green. Do any
red-leaved acers stay red throughout summer?


Shin deshojo is by all accounts a great tree, sounds like that's what
you have.
You're lucky to have a good one, apparently the cultivar is somewhat
diluted and
there are some around that don't look very flash in springtime.

There are red leaved cultivars of A. palmatum that stay red through the
season:
Okagami, Trompenburg, Fireglow, Bloodgood. But they all tend to fade a
little in the
shade (with maybe the exception of Fireglow), so it's a balance between
leaf burn
and colour loss. Also of course culture counts, it is widely believed
that too much
nitrogen will cause greening.

My Deshojo stays nice and red, it's in pretty heavy shade.

cheers,

-E