As some of you know, I grow bonsai. This may be mentioned in DSMV, as it is now
a worldwide pandemic.
I have a Juniperus squamata 'Prostrata', which is often sold as J. procumbens
'Nana', as the two are very similar. For years I have been growing it
essentially as a subtropical. It is outdoors all summer with the rest of the
bonsai, until October or November, the first night under 25 F, about -4 C. Then
it goes into an unheated sunporch, which eventually goes a little below
freezing. The blinds are down during the dormant period, so there really isn't
any sun at that time. In December or early January, the above-mentioned juniper
& other subtropicals are placed under fluorescent lights in a warm plant room
with the humidity around 70%. They wake up & go to town. Then they go back
outdoors in April or May. Last spring I got mad at this juniper, cut the top
off, and planted it in the ground for a few years. I also have a 'Shimpaku'
juniper, which is a cultivar of J. chinensis. I inquired as to whether I could
give the Shimpaku the same treatment. My bonsai teacher, with 40 years
experience, said no, it would not work; the Shimpaku needs the full winter
dormancy and back outdoors. However, he could not explain why. Are there any
botanists here who can explain the difference in temperature tolerance,
physiology, or whatever? Are there other junipers which would also thrive under
the same conditions as the J. squamata?
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)

Iris Cohen schreef
Last spring I got mad at this juniper, cut the top off, and planted it in
the ground for a few years.
I inquired as to whether I could give the Shimpaku the same treatment.

+ + +
Short answer: Yes, you can cut the top of your 'Shimpaku'.
What this will do is another matter.
You are unclear about the effect this had on your J. squamata.
Also there is a mystery. The way I count, if you cut off the top last spring
and put it in the ground a few years, then for you to know the outcome now
is either 'botanic fiction' or you found a way to create a time loop?
PvR

Yes, you can cut the top of your 'Shimpaku'.
What this will do is another matter.
You are unclear about the effect this had on your J. squamata.

Oh, dear, and I thought I was making sense.
No, I have no intention of cutting the top off the Shimpaku. It is styled the
way I want it. What I meant was, can I treat the Shimpaku like a subtropical,
give it about 2 months of dormancy, and then put it under the fluorescent
lights until spring? My teacher says no, it has to spend the whole winter in
the cold sunporch & then go outdoors in the spring. I would like to know what
the physiological difference is between the two species.
Since the J. squamata has only been in the ground one season, I can't see much
effect yet. I know it will eventually thicken the trunk. The remaining branches
will continue to grow. Of course I won't know the exact outcome for a couple of
years, but that does not concern me.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)

Iris Cohen schreef
Oh, dear, and I thought I was making sense.
No, I have no intention of cutting the top off the Shimpaku. It is styled
the way I want it. What I meant was, can I treat the Shimpaku like a
subtropical, give it about 2 months of dormancy, and then put it under the
fluorescent lights until spring?

+ + +
This is still not entirely clear.
You applied your strategy for subtropical plants to your J.squamata (against
advice) with results that were so maddening you cut the top out. Now you
want to apply this to your 'Shimpaku' (also against advice), although it is
now doing what you want of it. Something is missing here.
PvR