my fellow Indonesians! Apa kabar
Bli? 
I'd say the weather in Bandung is similar with mountainous region in Bali, 700m above sea level.
soil mix is lava rock in bulk unsieved unwashed, mixed particle size
with a little bit of goat manure
germination rates was around 80%, standard 24h soaking then straight to sowing media
I got my seeds from F.W. Schumacher hand carried by a friend, it was pre-covid.
Still got a few in the fridge, last time I sow (mid 2021) it still germinate.
It was the damping off that kills many of the germinated seeds, probably because of unsterile media.
And the seedling cutting that didn't root. So my survival ratio was low on damping-off & seedling cutting, around 10%.
I notice you have successful air layered your JBP? I should try that too!
Last week I cut some shoots and stick it to media, hopefully it's a successful cuttings.
Thanks for sharing your growing experience Benny.
Yes. Please give air-layering a try, especially on certain branches which you intend to cut.
But if your branching is causing undesirable "whorls" - swelling at the intersection between the main trunk and the start of the branch, please take action early.
The trick for me on the JBP air-layers is: CLONEX Purple Rooting Gel - why?
In January 2023, I attempted an air-layer on quite a thick branch, usually after 90 days, I should see some roots forming.
March, April went by, and nothing happened.
[Early May 2023 ] As I opened up the air-layer to check, the area of where I have cut out the cambian has started to callus. <---- This is perfectly normal, as most JBP airlayers do not take. In all honesty, I was even surprised that I could air-layer a blackpine (at all).
What I did was, scrap off and make another clean incision above the callus area, remove any cambian (green) to expose the white (non-green), apply a generous amount of CLONEX purple gel, cover up with moist sphagnum moss, and wrap it up.
Just 2 days ago, I noticed at the bottom right corner of the air-layer, and thick roots were forming.
This is the first time, I have rejuvenated an air-layer which has callus over time with no roots > to new rooting taking place.
My logic to this is either luck or most definitely the large amounts of Clonex that I have dumped on that new airlayer.
Luck, Clonex; Clonex Luck.
I noticed you are using slow-release Osmocote type fertilizer too. (see: blue dots in your lava soil)
The trend in Indonesia with the usual JBP seedlings for sale on Shopee and Tokopedia is that they are mostly grown in "sekam mentah".
I have heard that many JBP growers has success with Sekam Bakar. To me, sekam as a soil media is way too light, and I cannot grasp a hold on when to water next. Inorganic soil mixes seem to be better suited for my JBP growing.
I started somewhere in 2019 too - pre-covid.
The 1st mix I was experimenting with consists of : 1/4 bamboo humus, 1/2 black sand (pasir malang), 1/4 sekam mentah. Mostly organic. I would fertilize with Osmocote 17-11-10.
[this is the period where I killed the most JBPs , lots of damping off, bacteria, water regime / routine problems]
The 2nd mix was mostly advice by Bonsai Nutters here: 1/3 Akadama, 1/3 Pumice, 1/3 Lava rock - This mix has served me really well till now.
Especially in Colander baskets.
[this is period where I just kick back, stop stressing, and let the juveniles grow and grown, repot once in 3 years to a bigger colander, no disturbance to the roots, just adding more soil media, and allowing a bigger root space]
In between, as my water is really alkaline at 8.3 - 8.5, I started placing pine bark as top soil to ensure the soil media keeps a slightly lower pH environment as most plants require a pH 6 - 6.5 to thrive.
At the moment, I am just using 50/50 Akadama + Pumice.
Long candles have been shooting out since end of April till now. Elongation still on-going on some, on others: some new shoot formations.
Are you planning to style your biggest JBP beast with nice thick trunk profile soon? Maybe repot in a proper suited bonsai pot?
What are your progression thoughts?
