@garywood or anyone, have you had good experiences with PGRs, plant growth regulators? Some info out there on roses, but I've found nothing for quince.
So I've been looking into what works for roses, and what I've found is Concise and Sumagic are good on Knock Out roses. Bonzi, what I have access to at the moment. Effects and safety on roses is limited per one source.
I'll try it on some cuttings in the Spring. By then I may have access to some Sumagic.
What I am aiming for is shorter internodes. Flowers can wait if flowers arẻ going to be affected. If successful, I expect to be spraying or drenching once or twice a year.