You may want to do a simple soil test to see if it isn't your soil, but other than the phosphorous being unavailable but potassium could also be the problem.
I'm in zone 8, so the last frost was about a week ago. When I say it gets a "little chilly" I mean... its 55! Lol
I have them in homegrown compost, but it could be the problem. They're getting ready to gointo the garden very soon, so I don't know that I want to have my compost tested this year.
I honestly have no idea what kind of tomatoes they are. It kinda drives me crazy, but it is what it is.
I guess the only way to know is to just wai I guess.... I'll try to get some more garden-tone on them, maybe get some tomato-tone?