That's really hard to say as it depends on a myriad of factors; however, that size rockwool would be fine for sexing plants. Even if they become rootbound, they will still show sex (they'll just stop growing in size).
gainesvillegreen Reviewed by gainesvillegreen on . Plants in rockwool slabs until sexing? I have 3"x3"x4" slabs... planning on leaving them in just rockwooll without hydroton until i switch to flowering and can eliminate the males. how long do you guys figure i can leave them in the rockwool before they become to rootbound and need to be transplanted into hydrton? thanks Rating: 5