my blueberry plants are growing in 7'' high by 5'' diamter pots, will this be large enough until i find out the sex?
I would say that all depends on how large you want to grow your plants. If you plan on keeping them really small then I would say those pots are fine. My plants are only 8-9" tall and already they have been transplanted into 2gallon pots. The pots you are talking about are probably like the ones that I started with and under good conditions they would be ready to transplant after 3-4 weeks.
Cronaholic's right on this one--unless you want small plants or wanna risk your plants getting rootbound, consider re-potting in the near future. My plants are two weeks and some change and I just repotted them from 10" terra cotta pots(about 1.5gallons) into 5-gal pots less than an hour ago. While doing so I saw that the roots had already made their way through a good 65% of the soil.
Those should be adequate for a while. Just check the bottom drainage holes for when you start seeing root tips. As soon as this happens, change the pots out for bigger ones.
I dont know why yall change pots so many times im just doing two from the 26 oz cup to a 3 galllon grow bag thats all probally gonna do 5 gallons next grow when im gonna top and fim and more time two like 2 months veg im just experimenting