Plants that flower in September

• What to plant in September

Mexican sunflower (Tithonia rotundifolia)

Mexican sunflowers (Tithonia rotundifolia) look like a cross between a sunflower and a dahlia, and are easy to grow from seed. They are useful for adding height to a border (they reach 1.8m tall) and last well in a vase.

Dahlias

In colours of every hue and in lots of different flower shapes, dahlias make fabulous border plants and cut flowers. Earwigs can spoil the blooms - catch them in upturned flower pots on sticks, filled with straw.

Sunflower

Not all sunflowers (Helianthus annuus) are yellow - some are orange/red, or even rusty brown. They make excellent cut flowers, but be sure to leave a couple for the birds, which love to peck seeds from the dead flowerheads. Check out Monty's giant sunflower trial.

Aster

The daisy-like flowers of asters provide welcome colour in the garden right through to November and, unlike many fiery coloured plants at this time of year, these are mostly blue, pink and white.

Cleome

The spidery pink, purple and white flowers of cleome are an intriguing addition to a border or a vase. They are easy to sow from seed in spring.

Crocosmia

Crocosmia offer the ultimate in fiery autumn colour, in shades of red, orange and yellow. Their branched spikes of flowers add an interesting dimension to a vase.