At its best:
Sep, Oct, Nov
Fill the pot two-thirds full, using good quality, multipurpose compost.
Position the tallest plants first, teasing out the roots as you go. As a general rule, the taller the plant, the further towards the back of your container it should go.
Add the remaining shorter plants to the front and sides, then fill in the gaps with more compost, firming down well with your hands.
Water the container well and move it to its final position. It's important not to let the compost dry out.