I found myself with the economic and emotional motivation to try and grow cold temperate species in subtropical Brisbane. After my plant & bonsai collection grew to include plants which grow well up here near the Tropic of Capricorn, I still needed maples. And a ginkgo. And to smell a lilac. I acknowledge it's an uphill battle, so I did my research. The real experiment begins on Thursday, for the duration of June & July. Below are my aims & outline.
Great success is, if the plants can show off their Autumn colours, stay healthy throughout Winter and the future
Expected success is, the plants will be healthy through the Winter into the next year. (It's commented that a healthy plant can pass through a warm Winter and grow, so that health is about 2 or more years on from the present moment.)
Failure is, everything dies and I cry
As a home project, I've enjoyed this so far and after toying around, I expect success
This conversation on BonsaiNut is rather informative. Further research is less productive. Eventually my post will appear on that site too.
https://www.bonsainut.com/threads/japan ... nts.43585/
Basically, cold Winter destroys some imaginary "stuff" which is in the leaf buds thereby invigorating the plant. More specifically; by reducing daylight length, defoliating and maintaining temperature for 'Chill Hours'. Ideal Chill Hours is 1000 hrs between 0-7c. However another model may be used, and there's one fellow in Sao Paolo who swears his maples thrive. So my experiment will use the other model, which is temperature between 0-12 is good and ought never rise higher than 17.
The aim is to control the temperature, without spending the whole fortune.
If we research how to build a wine cellar or a florist's fridge, we find pre-existing home projects which achieve a similar aim. We also find a eksy price tag for the good stuff. In essence, buy insulation material then insulate an area. Next cool it with an expensive refridgeration unit.
Rather than that unit, I chose a chest freezer and gel-packs which can freeze down as low as the freezer goes. I bought XPS insulation and supplement it with cardboard. Inside a 2m square grow tent I laid out the XPS panels and made a base. It's not great, and the remaining tent walls are being lined with cardboard from work. I built a second chamber inside, and that is much smaller and it's more effective. A thermometer records data onto a table, then transmits via BlueTooth. It shows that humidity is typically 60-75%. This is bothersome, as 40-60% seems preferred from online research. The garage is 2-5 degrees warmer than reports from the Elders Weather website about my suburb. The chamber often rises to garage temperature, and is held at lows for about 6 hours. No success reaching 7 degrees in the larger chamber, main range so far is 13-20c. The smaller chamber's range is 8-15c.
My collection includes three large pot plants, and assorted smaller plants. As the large plants wouldn't fit in a little box, I was pre-committed to a large production. I've completed 80% of the outlined construction above and held the plants inside for most of this month. So far the Ginkgo went yellow, the Emperor went red, Osakazuki went orange, and the Shindeshojo is totally green and defiant. The smaller plants, most maples and a mail order lilac which arrived leafless, are leafless. Everything will be defoliated on the 1st of June.
In my yard, the Liquidambar is green. Which bugs me, as it is supposed to be more reliable for producing red leaves in warmer winters. A maple I bought from the South side of the river (probably Acer Serrulatum) only produced a few red leaves before the leaves were eaten by something. Point is leaving the plants in the yard did not produce nice Autumn colours.
Photos and further details will come later. When the time finds me, I will write-up a recommended plan and budget for a single smaller cool chest.
I will post the daily routine. I will post the estimated chill-hours at the end of Winter and visual health of the new buds. Hopefully, next year I'll re-post here with more info
