My limited experience with persimmon (grafted american varieties) has been that they are VERY slow growth. It can be frustrating looking at them and comparing to my apple, pears and peaches etc. but I've not planted one that hasn't been like this. I've heard that spring watering is very important of course but I'm in KY and water is not a problem in the spring... so I don't know what advice to give you. If someone else replies with some good tips I'm likely to try them here as well.

Edit: I don't amend my soil with anything so probably a nitrogen / fertilizer issue for me. I assumed my cattle on the uphill pasture would take care of that but thinking about it now... I might add something special to the area around the trees this year.

Good to know that it could be that they're slow. And you are right that it does seem worse if planted next to other fruit trees. Thank you for your input.