The secret is to get the biggest possible basket or container. The bigger it is, the more soil it will hold, meaning more moisture and nutrients.
If you choose too small a basket, you will spend all your time watering it – and those plants will get very thirsty in summer. Check for drainage, too. If water can’t drain away, soil will become waterlogged. Some containers, such as wicker ones, come pre-lined with plastic.
Punch a few holes in the bottom of the lining so water can escape.
Plastic tubs usually have drainage holes drilled in the bottom but it’s worth putting crocks in, too. This is a layer of gravel or broken pottery to stop compost blocking the drainage holes.
Rounded baskets will roll about when you’re preparing them, so balance it in the top of a bucket or plant pot to keep it still while you’re potting up.