Use those for the first transplant, and start in something smaller, like the size of a Dixie cup. Read the FAQ post about why to transplant.

You can tell if it is rootbound when you tip the rootball out of the container and roots are coiling around the bottom of the cup. Or when the leaves start to curl under.
stinkyattic Reviewed by stinkyattic on . 18 Oz Party Cup Veg I know a lot of you out there use those 18oz Party Cups for your starter. How long do you recommend keeping them in a cup that size before transplanting? Is there a way to tell if the plant is rootbound? Rating: 5