Being on the coast we have a small garden and I have everything in pots. I grow cottage garden plants, roses, Mahonia, bulbs, peonies, magnolias, clematis, salvias, summer bedding for extra colour. I have a bonsai and several other shrubs for green interest, ferns. it is great as I can rotate the containers for seasonal interest. This year I have added some grasses, an Ilex, and others for height and structure at the back. In some containers I have more than one plant creating a colour combination. I tend to stick to plastic containers for moving around and use terracotta ones at the front for show. The bigger the container the easier to water. So good luck designing your pot garden.