Shimpaku juniper growth rate

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JL42
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Shimpaku juniper growth rate

Post by JL42 »

Hi all, I'm fairly new to bonsai
Several months ago, I potted a shimpaku juniper into a styrofoam grow box
It's currently growing well in a mix of scoria and sieved pine bark.
The trunk is currently 2cm thick at the base and I am wondering how long would it
Take for the plant to get a trunk thickness of 4-5cm
Thanks
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Re: Shimpaku juniper growth rate

Post by treeman »

JL42 wrote: The trunk is currently 2cm thick at the base and I am wondering how long would it
Take for the plant to get a trunk thickness of 4-5cm
Thanks
10 to 15 years.
Mike
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Re: Shimpaku juniper growth rate

Post by bki »

I believe what treeman has said 10-15 years in Melbourne weather and growth rate. Your mix is a very acidic side for the shinpaku, the same mix I used about 4 years ago before I added pumice. I use 4-6mm sieved pumice, scoria and orchiata now and I noticed a changed in vigour on foliage. This year I added some akadama for experiment.
I am not sure with the weather and growth rate of cold climate species in your place so it is something you have to find out but using a large floor area grow box for shinpaku is debatable if the foliage cannot shade that from the heat of the sun. Soil will heat up from the heat of the sun and dries up quickly. a deeper and not wider container is ideal grow box for shinpakus.
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Keep Calm and Ramify
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Re: Shimpaku juniper growth rate

Post by Keep Calm and Ramify »

treeman wrote:
10 to 15 years.
Yep I agree, container grown possibly 20yrs to get to the 50mm mark.

https://www.ausbonsai.com.au/forum/view ... 31&t=25000
Last edited by Keep Calm and Ramify on October 18th, 2018, 5:25 pm, edited 1 time in total.
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Re: Shimpaku juniper growth rate

Post by bki »

that is one nice and healthy shinpaku KCaR
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JL42
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Re: Shimpaku juniper growth rate

Post by JL42 »

bki wrote:I believe what treeman has said 10-15 years in Melbourne weather and growth rate. Your mix is a very acidic side for the shinpaku, the same mix I used about 4 years ago before I added pumice. I use 4-6mm sieved pumice, scoria and orchiata now and I noticed a changed in vigour on foliage. This year I added some akadama for experiment.
I am not sure with the weather and growth rate of cold climate species in your place so it is something you have to find out but using a large floor area grow box for shinpaku is debatable if the foliage cannot shade that from the heat of the sun. Soil will heat up from the heat of the sun and dries up quickly. a deeper and not wider container is ideal grow box for shinpakus.
the weather of my area (north west Sydney) is usually quite hot in summer, it gets in the high 40s so im not too concerned with excessive moisture retention either.
i probably should have stated this earlier but the mix is around 75% scoria and 25% bark, it is free draining but the foliage shades most of the soil surface. i haven't tested the soil for acidity yet but from my observations the plant appears to be growing well. i checked the holes of the styro box yesterday and i noticed planty of roots growing through the bottom, some roots even grew straight through the foam box. the foliage growth also appears to be quite healthy, although it hasn't extended as much as the other shimpakus which i havent repotted yet, presumably because i repotted it which slowed it down. the current grow box holds around 18l of soil and ive poked plenty of holes in it to ensure good airflow and drainage.

for fertilizers, ive used some slow release fertilizer and have alternated every few weeks between fish emulsion and my homemade vegetable hydroponic nutrients which works great in the hydro veggie garden. im still unsure if foliar feeding is helpful for junipers so if anyone with experience has information, that would be helpful.

ive also heard from several sources on the internet how a warmer climate encourages faster growth on junipers, im unsure whether this is true so again, if anyone with experience has information to clarify, that would be greatly appreciated.
JL
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Re: Shimpaku juniper growth rate

Post by shibui »

In ideal conditions, allowing free growth with little if any pruning you may be able to double the trunk thickness in 5 years but I have also found these to be frustratingly slow so it seems to take forever. Much more likely to take longer so Treeman's estimate of 10 -15 years is probably reasonable for many less experienced growers.
Not sure how climate affects juniper growth. We get well into 40s in summer but probably a lot colder than Sydney in winter so you may have some advantage with more growth over winter and increased growth rates in spring and autumn.
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Re: Shimpaku juniper growth rate

Post by bki »

Hi JL, it seems your shimpakus are more vigorous than with mine. maybe because your soil mix has better matched the weather in your place. I haven't read so much about shimpakus in Melbourne so I based all my regiments based on my experienced and experiments. Maybe i'll get a good soil mix that will match the Melbourne weather someday. on foliar spraying, I do it with power feed and seasol (weak solution) weekly in spring tapering to monthly in winter. I do it after misting the foliage (which I do everyday from late spring to end of summer) I use a watering with mist option on the dial. so that makes me wonder what is working, the misting or the foliar feed, I'm not so sure.
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Re: Shimpaku juniper growth rate

Post by JL42 »

bki wrote:Hi JL, it seems your shimpakus are more vigorous than with mine. maybe because your soil mix has better matched the weather in your place. I haven't read so much about shimpakus in Melbourne so I based all my regiments based on my experienced and experiments. Maybe i'll get a good soil mix that will match the Melbourne weather someday. on foliar spraying, I do it with power feed and seasol (weak solution) weekly in spring tapering to monthly in winter. I do it after misting the foliage (which I do everyday from late spring to end of summer) I use a watering with mist option on the dial. so that makes me wonder what is working, the misting or the foliar feed, I'm not so sure.
I'm unsure if my shimpaku juniper is a true juniperus chinensis sargentii though.
When I purchased the plant, the label on it stated that it is a 'juniperus x media 'shimpaku'
The label further describes it as:
"Dwarf slow going shrub. Foliage deep green held in a case shaped plant. Good for bonsai, rockeries or tub specimen
Grows 75cm high in ten years"
So I'm wondering if there's a possibility of it being a hybrid with something else.
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Re: Shimpaku juniper growth rate

Post by shibui »

Probably the same plant. X media is one of the alternative names J. chinensis has been known as. There are a lot of junipers with several names because they are hard to identify.
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Re: Shimpaku juniper growth rate

Post by bki »

btw JL, my first shimpakus are from Shibui. I just realized while reading his comment. :worship: I wish bought more...
more trees.....
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