Whilst all of the points raised previosly are valid to a certain extent, there is one critical factor that has been overlooked and that is the compost. In the wild, maples get 7 to 8 in. of rain a month during the summer and grow in free-draining volcanic soils. Replicate that and you can happily grow any Japanese maple in any size pot in full sum and in temperatures from -20 deg. c to shade temperatures of 35 deg. c without any damage providing you start with a healthy plant. As this is my first post I've kept this message short; hopefully this post has been made correctly. If you would like me to expand on the above, I will be more than happy; I speak from a small amount of experience as a commercial propagator and grower of Japanese maples for the past 25 years.

"lammas" wrote in message
...

Mike Lyle Wrote:
"Franz Heymann" wrote in message
...-
"Mike Lyle" wrote in message
om...

[snip]-

I'd also guess (but it's only a guess) 40 cm is too big a pot:
best
way is the old rule of patiently going up one size at a time, and-
only-
when the roots have definitely reached the outside of the old
pot,-
so-
that any water you give will immediately go to the plant, rather-
than-
hang about going stagnant. (Some people, in this group notably-
Franz,-
ignore this rule without ill effect; but they have a watering
regime
to suit.)-

That is an urban legend. If there were any truth in it, all
plants
planted in the open ground, which is an infinite sized pot for
practical purposes, should fail.

I planted a very young Acer palmatum atropurpureum directly in a
45
cm
pot about eight years ago and have never repotted it. It
thrives.-

We've done this one to death before, Franz. I still maintain that
you
operate a sensitive watering regime which avoids causing damage.
And
that the open ground in a typical garden doesn't resemble a
container,
as it doesn't prevent water-movement and air-entrainment.
Waterlogged
areas of open ground are just as deadly to most plants as
water-logged
containers.

Mike.
Whilst all of the points raised previosly are valid to a certain
extent, there is one critical factor that has been overlooked and
that
is the compost. In the wild, maples get 7 to 8 in. of rain a month
during the summer and grow in free-draining volcanic soils.
Replicate
that and you can happily grow any Japanese maple in any size pot in
full sum and in temperatures from -20 deg. c to shade temperatures
of
35 deg. c without any damage providing you start with a healthy
plant.
As this is my first post I've kept this message short; hopefully
this
post has been made correctly.

Not quite. Unfortunately you have tampered with the attribution
marks, so that it is no longer possible to distinguish who said what.
Remember never to touvh the "" key when you reply, and never to erase
any existing "" marks at the beginning of a line. Your software will
take care of all that automatically.

Having said that, the points you made are of course entirely valid and
very helpful.

If you would like me to expand on the
above, I will be more than happy; I speak from a small amount of
experience as a commercial propagator and grower of Japanese maples
for
the past 25 years.

You are too modest.

Franz