Moving Box Plants to a bigger pot

I have three small box plants that I bought earlier in the Summer. When can I transplant them? What soil mix should I put in their new pots? How big should their new pots be?

Thanks for your help. I know nothing about these plants.

 

Awhitecat, welcome to GC, those hdges look alright in that pot for now. Whne you see the roots starting to crepp through the drain holes at the bottom is when you should transplant and then only the next size up. The idea-I think is to have just enough room and no more, so as to prevent over watering and then rot etc. The ideal mix (in my own opinion and everyone has their own "magic mix" believe me), is 1/3 well rotted compost, 1/3 vermiculite and 1/3 topsoil, into that I put a cupful or two of potash and a light sprinkling of slow release food granules. That is my basic potting mix. It should feel quite light and easy to swirl around with your hands.

I have just reread and noticed my shocking spelling and that I haven`t said a third of what? About a washing up bowl of each into a big bucket.

 

Hi Awhitecat
I had a box in a pot on my patio all last winter,they dont grow much in the winter :thumb:
I planted it in about march ,i just put it in the soil where i thought i wanted it to be ,
i have now re thought that area of my garden,and i will leave it in situ for now,but in early spring i will dig it up and replant it in a pot as i have purchased a topiary squirrel frame, and box is the perfect plant