I really don’t know.
To me if 70 days mean from seeds sprouted to picking, I should have picked BM by Sept 10. I would think the fruit would not have ripened then.
It does not make sense to me to count ripening days from the day seeds sprout. What if your watermelons set fruit 1- 3 weeks apart? By that method, don’t you need to pick every wm on the same days?
I don’t know. I have never grown watermelons before.
But most info on line I’ve seen says counting fronm the day seeds sprout.
I have two OG that I don’t know when to pick, either.