Give your garden a new lease of life in August with sunny perennials such as achillea 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: Achillea 'New Vintage Red'
Achillea (yarrow) is a must-have perennial for sunny mixed borders. Its flat-topped flowerheads add horizontal interest to your flower bed’s mid-layer and are a landing pad for bees and butterflies. As well as being attractive to wildlife, achilleas tick my other two boxes for busy gardeners – they’re low maintenance and relatively drought-tolerant.
You can find an achillea to suit any colour combination, but I love the red, jewel-like flowers of Achillea ‘New Vintage Red’. It gives a pop of colour throughout summer and into autumn. Plant it in a cottage or prairie-style border in full sun or in containers. Yarrow is often used as a medicinal herb and grown in kitchen gardens to attract pollinators and pest-eating insects.
Plant it with…
Salvia 'Bumbleblue': This clump-forming sage won’t overwhelm yarrow, and the violet-blue flowers complement the cool-red tones of Achillea ‘New Vintage Red’.
Aster x frikartii 'Mönch': The tall, sturdy stems and daisy-like flowers are a lovely counterpart to the more delicate yarrow. It flowers in August, adding late-season colour to your garden.
Thyme: Yarrow pairs well with most herbs. Plant it in a container with lilac and white thyme in a sunny spot near your kitchen door.
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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…
Rosa 'Sunny Sky': Roses and alstroemeria have similar requirements, making them natural companions in an English garden. This variety has fragrant, soft-yellow blooms.
Rudbeckia 'Happy SmileyZ': 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.Â
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 the subtle calm of ‘Limelight’s blooms. Plant it with evergreens to create a tranquil hideaway in a large garden or pair it with colourful perennials to create a bright border.
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 'Magical Blue Globe’
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 – when the colour fades, they still add an ornamental touch to your garden.
Eryngium 'Magical Blue Globe' has gorgeous silvery-blue flowers that mature to a deep indigo. It’s an easy plant to look after, but it does prefer a sunny spot and 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.
Allium ‘Gladiator’: A complementary stunner for a cool-toned bed, the flowering period for this striking purple allium overlaps that of Eryngium ‘Magical Blue Lagoon’.
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.
Verbena bonariensis: Verbena’s small flowers and tall, delicate stems soften crocosmia’s bladed leaves, making it a colourful counterpart for a cottage-style garden.
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.Â
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. Achillea ‘New Vintage Red’ is our plant of the month – it looks great in a border with sage, asters and rudbeckias. 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. Choose Poppy ‘Brilliant’ for classic red flowers or the striking Poppy ‘Black Peony’, a deep purple double-flowered variety.
