This is my 4th season growing tomatoes from seed. I have noticed that the maturity date specified on seed packets doesn't seem to hold true for me. An example is my Pruden's Purple-67 days have very few tomatoes on them, but my 1884- 85 days are covered with fruit up to about the size of a tennis ball. It is mid June in Minnesota, can anyone explain this? I do purchase seeds from several suppliers like Tomatofest, Baker Creek, & always a couple hybrids from Burpee.