what size container

[grawrc]

Outside my shed  I have 2 square wooden planters about 30x30x30cm. The bottom is open to the soil so the roots will be able to go down as deep as they like.
In my garden I have some salvia microphylla "hot lips" which I'd quite like to put in the planters. Are they big enough? And if not what size of planter would they need?

[grawrc]