Dahlias put on a show in summer and autumn. They come in a wide range of colours from pastels to brights. Very floriferous, they're also good for cutting. Free-draining, lighter soils, where they are more likely to survive the winter. While they will grow on heavy soils, you are more likely to need to lift the tender tubers at the end of autumn as they would otherwise suffer when heavy ground gets colder and soggier in winter.