I have problems growing green shiso (perilla), The red shiso is easier to grow but is more suited to pickling than eating with sushi or sashimi.
How do you get the seeds to sprout? I have tried many times and I have yet to succeed sprouting seeds on purpose.
I have grown shiso from cuttings, but the cuttings will bolt the same time as the parent plant.
I did allow a hybrid red/green shiso to reseed. I got a lot of seedlings. A couple of those did mature and lasted quite a long time in the garden (all summer) getting up to 4 ft tall before bolting. They grew in full sun in the summer, so it was not heat alone that caused bolting.
However, when I tried to pot up the extra seedlings, half of them bolted to seed even though they were very young.
Have you got any ideas on how I can get green shiso to sprout more reliably and why some seedlings are bolting so young?