J-4 - is it naturally a super dwarf?
I purchased two specimens of J-4 from two different Thai ebay retailers back in 2008, one a small one tipped rooted/grafted plant, another a two tipped cutting that took almost a year to root. They both started off slowly, and the cutting I had to root took several years to get going. The larger grafted cutting now is around 30 inches tall with many many tips, in a 15 gallon pot. The smaller one didn't grow much and I finally moved it from a 5 gallon pot to the ground in spring 2013.
Well both are multiple tipped now, the smaller plant in the ground is still less that 2 feet tall, the one in the pot is around 30 inches tall, but both are amazing trees:
Before leafing out, with first a 12 inch measuring stick, and then with a yard stick:
The shorter one:
The taller one with a yard stick... 30 inches tall more or less:
Finally, recent pictures of both in bloom - I added one of the short plant with my cat Loki next to it to show you how short it is even after a year in the ground.