Give your garden a new lease of life in August with sunny perennials such as Erigeron and alstroemeria, show-stopping crocosmia and architectural sea holly.
By August, your early-summer flowers may be looking a little tired. Fill any gaps in your borders and brighten up your patio containers with these August flowering plants, which will add colour through to the autumn.
Key jobs in the flower garden this month include regular deadheading, watering and taking cuttings. Find out more in our August gardening jobs checklist.
August flower of the month: Erigeron karvinskianus
If recent summers have taught us anything, it's that plants that look after themselves in hot, dry conditions are worth their weight in gold. Erigeron karvinskianus (Mexican Fleabane) is one of these plants. It thrives in poor soils, is extremely drought tolerant, and is more likely to suffer from too much attention than from neglect. It doesn't like wet feet, so if you have very heavy soil that gets waterlogged over winter, plant it in pots or use it to add colour to walls, paths or other places usually occupied by weeds.
Erigeron karvinskianus has small, daisy-like flowers that shift from white to pink as they mature. It has an exceptionally long flowering period, meaning you can enjoy this two-tone display from as early as late April through to October. It naturally self-seeds and is particularly effective at softening rocks and hard landscaping, giving a romantic, cottage garden feel to your space.
Erigeron karvinskianus is our August flower of the month – add it to your basket and get 25% off this month.
Plant it with…
Achillea 'Lilac Beauty': Plant Erigeron karvinskianus in front of this yarrow for a soft, harmonious summer colour palette. The flat-topped clusters of lilac flowers fade to white, complementing the ever-changing display of Erigeron flowers.
Thyme 'Silver Queen': This fragrant herb has variegated leaves with a silver tinge that provides a lovely backdrop for the delicate flowers produced by Erigeron karvinskianus. A great pairing for gravel gardens, rockeries and stone walls.
Lavender 'Munstead': Combine the upright spikes of lavender with the tumbling habit of Erigeron karvinskianus to create a balanced display for pots and planters.
Alstroemeria 'Summer Breeze'
Alstroemeria (Peruvian lily) is one of my favourite flowering plants for August. The exotic blooms are popular August wedding flowers, but their long flowering season – from spring through to autumn – means you can enjoy cut flowers for a good six months of the year. Rather than deadheading flowers, pull their stems from the bottom to encourage the plant to produce more flowers. These sun-loving plants like fertile, well-draining soil and are hardy once established.
Alstroemeria 'Summer Breeze' has gorgeous orange-splashed yellow flowers, speckled with brown, and bronze green-rimmed leaves. Pop it in a container to brighten up your patio, add it to the middle of a mixed border or grow it in a frost-free greenhouse for a longer flowering season.
Plant it with…
Sedum 'Chocolate Cherry': The rich purple foliage of this sedum picks up the bronze tones in the alstroemeria's leaves. Plant it in front of Alstroemeria 'Summer Breeze' in a mixed border.
Rudbeckia 'Summerina Sizzling Sunset': Continue the sunset colour scheme with this bright perennial that flowers throughout the summer.
Stachys 'Pure Cotton': Lamb’s ear provides a mat of pale, furry leaves that contrast nicely with alstroemeria’s stronger tones.
Hydrangea ‘Limelight’
Panicle hydrangeas are more tolerant of heat than mopheads, making Hydrangea 'Limelight' an excellent choice for sunny or partially shaded spots. It blooms from mid-summer with its pale lime-green flowers turning to white and then eventually tinging pink in early autumn. Many people choose hydrangeas for their dazzling colours, but personally, I prefer these subtle blooms. Plant it with evergreens to create a tranquil hideaway in a large garden or use it as a backdrop for colourful perennials.
Hydrangea 'Limelight' is a dense shrub that can grow to over two metres, making it a good option for summer privacy. If you’re planting it at this time of year, make sure you water it regularly to help it establish strong roots.
Plant it with…
Echinacea 'SunSeekers Purple': The bright flowers of this coneflower add mid-height interest to a border, with ‘Limelight’ at the back and geraniums or grasses providing ground cover.
Buxus Sempervirens (common box): Dense, compact box hedging framing a mass of cloudy hydrangea blooms is a classic formal garden combination.
Nepeta 'Walker's Low': Plant catmint in well-drained soil in front of Hydrangea ‘Limelight’ for a cottage-style bed. Its aromatic flowers add colour and are a magnet for pollinators.
Eryngium 'Big Blue’
Sea holly (Eryngium) always catches my eye in a summer border. These architectural, spiky-looking perennials, which superficially resemble thistles, add colour, structure and texture to a sunny border. Bees love them, and they make a great cut flower. They also dry well, though I leave most of the flower heads on the plant, as when the colour fades, they still add an ornamental touch to your garden.
Eryngium 'Big Blue' has some of the brightest flowers in the sea holly family. Its large, electric-blue flower heads stand out against the most vibrant of late summer companions. Eryngium x zabelii 'Big Blue' is an easy plant to look after as long as it gets plenty of sun and is planted in well-drained soil. Eryngiums are drought tolerant and a good choice for poor soils or gravel gardens.
Plant it with…
Stipa 'Pony Tails': This luscious, feathery grass provides a beautiful contrast to sea holly’s sharp profile.
Salvia 'Pink Inspiration': Salvia's upright flower spikes offer textural contrast to the spiky flower heads. This variety has bright pink flowers that can hold their own against the vivid colour of Eryngium 'Big Blue'.
Achillea 'Sunny Seduction': Throw a splash of yellow into the mix with this sunny perennial – the flat-headed blooms and delicate flowers soften and bulk out a border.
Crocosmia ‘Lucifer’
The explosion of colour when my crocosmia blooms never fails to surprise and delight me. I’m less enamoured by its invasive nature, though it is possible to contain it if you’re vigilant about digging up unwanted corns. Smaller varieties of crocosmia grow well in pots, which is a good choice for smaller gardens, but Crocosmia 'Lucifer' is best given free rein to romp away at the back of a large border.
Crocosmia works well in both exotic and cottage-style borders. It prefers fertile soil and a sunny spot – though mine does seem to thrive in its relatively shady spot. Crocosmia 'Lucifer' is a taller variety, growing to over a metre in height, and benefits from some support to keep its long leaves and flowers upright. It’s hardier than other crocosmias, making it a good choice for northern parts of the UK.
Plant it with…
Agapanthus 'Northern Star': The blue star-shaped flowers of this Agapanthus are a perfect companion to the fiery tones of Crocosmia ‘Lucifer’.
Panicom 'Northwind': This tall grass offers some support for the Crocosmia ‘Lucifer’, while letting the fiery flowers peek through – a great option for a prairie-style border.
Helenium 'Moerheim Beauty': Pair Crocosmia 'Lucifer' with the rich copper-red and orange tones of this helenium for a fiery late-summer border.
FAQ
What flowers are in season in August?
Sunflowers, dahlias, roses, cosmos, verbena, alstroemeria, gladioli, snapdragons, rudbeckia, echinacea and sea holly all flower in August. Other plants that bloom in August in the UK include hydrangeas, buddleias and some varieties of clematis. Browse our summer favourites to find the perfect mix for your garden.
What flowers can I plant in August in the UK?
You can plant container-grown flowers and shrubs (including hydrangeas) out now as long as you water them in well. Erigeron karvinskianus is our plant of the month – pair it with drought tolerant herbs such as lavender and thyme or late-summer perennials like Achillea in pots, gravel gardens or well-drained borders. You can also sow hardy annuals such as poppies, nigella, cornflowers and calendula now to bloom in early spring.
What is the birth flower for August?
August’s birth flowers are the gladiolus and the poppy. Gladioli are tall, showy flowers that are a symbol of strength and love. Colourful poppies have long been considered a flower of remembrance. Common field poppies are hardy annuals, which you can grow from seed. If you want a low-maintenance perennial poppy, plant an Oriental poppy (these flower in late spring and early summer).
