7 of the longest flowering plants for effortless colour from August to autumn

We have a month or so until the summer ends and the shift begins, and it's easy to feel a little downhearted about all of the stunning colours that summer can bring.

So now is the ideal time to look at what can still give you beautiful colour during this transitional period.

We asked our experts what they would have in their gardens to give them effortless colour from August to autumn. There are some wonderful varieties to choose from, including autumn perennials – which will you pick?

1. Japanese anemone

This is a variety that's not mentioned as much as it should be. It's fast-growing and can get quite tall, so if you want something that will cover well, this is your go-to; it's also loved by pollinating insects.

'The blooms of Japanese anemone can begin to open in August, and can last up until October,' says Richard Barker, horticultural expert and commercial director at LBS Horticulture. 'As flowers fade, cut them off at the leaf joint to stop the plant from going to seed and trigger the production of new flower buds.

Julian Palphramand, head of plants at British Garden Centres agrees, 'For reliable colour that carries you from August into autumn, Japanese anemones are hard to beat. They have that slightly loose, romantic habit that works well at the back or middle of a border, and they’ll keep flowering for weeks if they’re happy.'

There are a couple of really beautiful varieties to consider. Robustissima has pretty pink flowers and will grow up to 90cm and 60cm in width, from £12.99 at Thompson & Morgan. If you're more of a purist, then consider Honorine Jobert with its crisp white flowers; grow it up alongside a wall for maximum effect, from £13.99 at Crocus.

2. Dahlias

'Whilst dahlias are not necessarily classed as low-maintenance, they are seen as ‘high-reward’ plants where a single tuber will produce masses of vibrant blooms over a long period, which enables them to add glorious colour through August, September and October when many summer flowers have finished,' explains Lucie Bradley, gardening and greenhouse expert at Easy Garden Irrigation.

Keep your dahlias going as long as possible with these top tips from Richard: 'To encourage the plant to flower for longer, cut away old, fading flowers so that it focuses its energy on producing more flowers instead of going to seed. Ensuring that plants receive six hours of full sun per day and watering during hot, dry weather also helps the plant to flower for longer.'

One of the most popular dahlia varieties is Café au Lait with its dinner plate head; the colour is more subtle, but the size will add impact, currently on offer for £12.99 for a 5-litre container, Gardening Express.

For a vibrant burst of colour, look at Purple Fox; its bright magenta pompoms will brighten up your garden, from £9.99, Thompson & Morgan.

3. Perennial asters

With their super pretty daisy-like look, perennial asters come in pink, blue, white and purple and will add a lovely display of colour.

'They can begin to flower in mid to late August, and continue deep into autumn,' says Richard. 'With each plant blooming for an average of four to eight weeks, the overall display lasts longer depending on the type planted.'

Richard advises deadheading regularly as this will keep the plant producing more flowers. 'Staggering pruning can delay flowers on certain stems to make the plant bushier and extend the flowering display too.'

Snow Cushion is a compact perennial aster that has pretty white flowers, £7.99 for a 1 litre container from Gardening Express. For more of an impact and a mixed colour look, check out Thompson & Morgan's Alpinus mixed, £19.99 for a 1 litre pot.

4. Salvias

Salvia is part of the mint family and comes in quite a variety of colours. It's great for patios or if you want to create a country cottage look – pollinators love them too.

Richard advises, 'Salvias can produce colourful flowers in August, and if trimmed or deadheaded, they can produce more flowers up until October. If salvias start to become leggy or slow down around mid-summer, cut a third of the growth to trigger another flush of flowers that can last almost up until winter.' After this flush, give your salvias a good prune before winter.

Give your garden a fiery look with the bright orange/scarlet colour from the Royal Bumble variety, 1 litre pot from Suttons for £24.99. For an almost neon pink, have a look at Rose Pink Marvel, currently £9.97, from Gardening Express.

5. Sedum

Sedum is part of the succulent group and is hardy and easy to grow. They're also a great drought-safe option with colours ranging from mid pink, green, blues, burgundy, white and autumnal shades.

What's interesting about sedum is that it changes colour with the season, so it might be light green or pink initially, then change to deep shades as autumn hits. It's a good option for ground cover, so use it in borders and rock gardens.

J.Parkers Autumn Joy, £3.99 for one first-grade loose root, has star-shaped flowers in a greenish pink that changes to raspberry pink and ends in a rich golden bronze.

For a multicoloured look, Gardening Express have a pack of five plants in their succulent sedum collection, currently £19.99.

6. Rudbeckia

'Rudbeckia produce daisy-like blooms that can last from August until October, or until the cold weather begins to kill off the flowers,' says Richard.

Also known as 'Black-eyed Susans', this is a striking flower to have in your garden with its droopy leaves, and they are definitely one to consider for your pollinators.

Keep your rudbeckia going as long as possible by cutting off old, dying flowers, as that can trigger the plant to produce new buds. 'It will also have more energy for flowering if it receives a few hours of direct sunlight per day.'

Buy Little Goldstar, currently £7.99 for three from Gardening Express, if you love the bright yellow colour. They're great for pots or mass plant them in your borders.

For a richer, more dramatic touch of colour, look at Cherry Brandy with its dark red petals and purple stamens, from £9.99 at J. Parkers.

7. Chrysanthemums

'Hardy chrysanthemums deserve a mention too, because they can be remarkably useful when you want something that keeps performing without much fuss,' advises Julian.

They love sunny spots, direct light and well-draining soil, and if you pinch growing tips in spring, they'll last well, possibly through until November.

Colour-wise, there's a wide choice; we love Amiko Violet, with its deep mauve blooms that will give your borders and pots a vibrant display, £19.99 for a 1-litre pot, Thompson & Morgan. If you prefer seeds, then Amazon's chrysanthemum Indicum Hortorum might be for you in different colours, £7.95 for 300.

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Follow our guide to give your garden some lovely colour over the next few months and give your plants some love so they can bloom for you as long as possible.