I don't know, I planted a row on a nice berm in my upper small garden patch, which is the best soil I have at the moment, June 5th, with a earthway planter, 90 day burpee silver queen, nothing came up, blame it on the rain. So I replanted that in 64 day corn. We shall see. Ok, so somewhere before June 21st I tried again, (lower patch and low and behold its up, but I don't know if its the darned planter, new last year, the rocky soil, well one side is) have some skips, frustrating, so I fixed that, I have 2 other varieties, less days, so I should get that late, I would have wasted $70 of seed had I planted the rest June 5th, next year I'll have to make sure the lower patch is done early, just could not get it done as early, late crop of potatoes is up and the liquid fence is working, I'll augment that with posts and fish line / cans, missed a 'chuck yesterday, well I'm out of practice, no shooting, set a trap today, I'll be darned, nothing but a struggle, it seems, but once its up far enough, it won't be so much a pain. Looking back I think it would have been ok earlier, but was dry, but can water, I'll take an "A" for effort. Cripes I even bought on the cheap $150.00, a Troy Bilt Junior to cultivate the patch, something better give LOL !