At its best:
Jun, Jul, Aug
First cut planting holes in your coir liner, then place a couple of layers of plastic, from an old compost bag, in the base of the hanging basket. Add compost, slow-release fertiliser and water-retaining gell and mix in with your hands.
Feed the campanula plants through the planting holes you've made in the coir, and add a layer of compost. Then plant the begonias in the top of the basket, filling around them with compost and firming well.