6 flowers to plant now for a colourful autumn display

Flower bed border between patio and lawn — (Image credit: Future PLC / Colin Poole)

Jump to category:

1. Penstemons
2. Sweet alyssum
3. Asters
4. Calendula
5. Violas
6. Nasturtiums

Summer can’t last forever, but your blooming garden can, as experts have revealed six flowers to plant in August for a burst of autumn colour this year.

If you’ve been wondering what to plant in August, you really should consider these beautiful, fast-growing flowers if you want your garden to be filled with colour for the new season, rather than patchy and bare.

Autumn is typically quite mild in the UK, and these fast-growing plants and perennials you can plant in August for autumn colour offer plenty more opportunity to enjoy your garden for longer.

1. Penstemons

Penstemons are a great alternative to foxgloves if you have kids and pets (they can be toxic), and with a flowering period from summer into autumn, are excellent for adding colour to sparse borders.

Group of Penstemons flowering in a summer garden.

Add pot-grown Penstemons to your garden in August, and these semi-evergreen perennials are likely to already be in bud and will quickly establish to provide virtually instant colour all the way through into October,’ says Lucie Bradley, gardens and greenhouse expert at Easy Garden Irrigation.

‘I particularly like ‘Pensham Just Jayne’ for its height of 90cm and its rose-pink blooms with magenta throats, perfect for adding colour in the middle of back-of-garden borders.’

Where to buy penstemons

2. Sweet alyssum

Perfect for adding bursts of last-minute colour to your autumn garden, sweet alyssum also makes a beautiful flower pairing with petunias for a showy, structured display. Why am I telling you this? Petunias also flower in autumn.

Closeup of sweet alyssum flowers in garden

‘Alyssum is particularly useful because it is quick to germinate and doesn’t need much space. Scatter seeds thinly across pots or the front of a sunny border and you can create low cushions of tiny flowers,’ says Andrew Jackson, an award-winning garden writer and founder of The New Build Manifesto.

‘It is a lovely gap filler and particularly effective around the base of larger container plants. The flowers are small, but collectively they create a surprisingly effective display and are useful to late-flying pollinators too.

Where to buy sweet alyssum:

3. Asters

Not only are asters one of the best autumn-flowering perennials, but they’re also fabulous for attracting birds and pollinators to your garden, too. This is ideal for garden wildlife, as food is not as bountiful in the cooler months as it is in spring and summer.

‘Add pot-grown Asters into your garden now, and you will be able to enjoy their vibrant blooms all the way through to the end of October, early November depending on the weather,’ says Lucie.

‘My favourite varieties of aster include ‘King George’, which produces glorious flowerheads up to 6cm wide of rich purple-blue and golden yellow centres, whilst ‘White Ladies’ makes its perfect companion if you plant this taller aster behind it, which can reach up to 90cm in height to provide a backdrop of crisp white flowers with similar gold coloured centres.'

Where to buy asters:

4. Calendula

Calendula is a self-seeding cottage plant that returns every year, making it an ideal choice if you want autumn colour year on year. It loves full sun and can do well in poor soil, making it a great choice for beginner gardeners, too.

‘Calendula is probably my first choice for a late sowing. It germinates quickly, grows enthusiastically and, given a reasonably warm September, can produce cheerful orange and yellow flowers surprisingly quickly,’ says Andrew

‘Sow directly into a sunny border or into pots, keep the compost moist while the seedlings establish, and thin them if they become crowded. They are wonderfully unfussy plants.’

Where to buy calendula:

5. Violas

Violas are beautiful winter flowers that can add pops of pretty colour on the dreariest of days. It’s a brilliant choice for winter hanging baskets and pots, flowering all the way from autumn until spring.

‘Growing equally well in the ground, in pots or in hanging baskets, violas are a great hardy, low-growing plant which flood the garden centres at this time of year so you can easily add a splash of colour into your garden over the autumn months,’ says Lucie.

‘Thriving in the cooler temperatures of the autumn months, even withstanding light frosts, violas with provide a long lasting display with their petite blooms which still pack a punch due to their range of shades from the cheerful ‘Penny Yellow’ whose bright yellow blooms through to the pastel shades of ‘Pink Halo’ with its soft white upper petals complementing the halo of violet-purple which surround the centre of each bloom.’

Where to buy violas

6. Nasturtiums

While the best time to plant Nasturtiums is between March and May, you can sow them now for a burst of autumn colour.

‘Nasturtiums are another good option because they grow incredibly quickly in warm conditions. I particularly like them for filling gaps around the edges of containers and raised beds, where they can tumble over the sides,’ says Andrew.

‘For an August sowing, choose a compact variety rather than a vigorous climber and give it the warmest, sunniest position you have. Don’t overfeed them, as rich compost tends to encourage lots of leaves at the expense of flowers.’

Where to buy nasturtiums

Then end of summer doesn't mean the end of your garden's flowering period. These six flowers are perfect for extending your garden's flower lifespan and filling it with stunning colour, too.

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Kezia Reynolds joined the Ideal Home team as News Writer in September 2024. After graduating from City, University of London in 2022 with a bachelor’s degree in journalism, Kezia kicked off her career spending two years working on women’s weekly magazines. She is always on the lookout for the latest home news, finding you the best deals and trends - so you don’t miss a thing!