August is the month when late-season plants start to flower in earnest and here are ten of the best to give your flower borders a burst of glorious late-summer colour and interest.
If you’re looking for an impact plant, ‘Spartacus’ Senior certainly fits the bill. Large, yellow-green buds open to reveal huge deep maroon flowers up to 20cm across, known as dinner-plate blooms! The flowers often fade to a rich, velvet red as they mature. And they are certain to be a talking point amongst visitors to your garden.
- Flowers from July to October
- Hardy
- Grows to 120cm tall and 60cm wide
- Rich, moist but well-drained soil
- Full sun
- Exposed
Top Tip
To ensure your flowers grow bigger, remove the side buds once the terminal bud is developed. If you don’t mind about size, leave the side buds, your blooms will just be a little smaller.
2. Crocosmia x crocosmiiflora ‘Emberglow’ (Montbretia)
These easy-to-grow plants provide a lovely splash of late-summer colour with long sprays of small, red flowers appearing above pleated green leaves. The seed heads look wonderful when added to a vase of cut or dried flowers.
- Flowers from July to September
- Hardy
- Grows to 90cm tall and 75cm wide
- Well-drained soil
- Sun
- Exposed
Fun Fact
This lovely plant attracts a very particular bird. If you would like to see more hummingbirds in your garden, if they live in your area, this is the plant for you.
3. Clerodendrum trichotomum ‘Purple Blaze’ (Glory Bower)
This wonderful, tall, deciduous shrub produces white, scented flowers in August, followed by bright blue berries surrounded by vivid red outer ‘petals’ which light up an autumn flower border! It will grow best in a sheltered spot and, if you’re looking for a feature shrub, some plant nurseries sell it grown as a standard tree.
- Flowers in August
- Hardy
- Grows to 450cm tall and 350cm wide
- Well-drained, fertile soil
- Sun to part shade
- Sheltered
Fun Fact
This unique and interesting-looking plant is actually a member of the Mint family, Lamiaceae!
4. Rudbeckia laciniata ‘Herbstonne’ (Black-eyed Susan)
Another easy-to-grow perennial which needs no staking; this cultivar produces citrus-yellow flowers with green centres on extremely long stems for many weeks and is perfect placed at the back of the flower border.
- Flowers from August to September
- Hardy
- Grows to 180cm tall and 100cm wide
- Well-drained soil
- Sun
- Exposed
Top Tip
The name ‘Herbstonne’ is actually German, so you may see this plant labelled with its English counterpart. Herbstonne is German for ‘Autumn Sun’, so look out for that name at the garden centre.
5. Ceratostigma plumbaginoides (Hardy plumbago)
This delightful plant produces the most intense, bright blue flowers in late summer, which appear from in between bright green leaves on long, thin red stems. Those leaves turn fantastic shades of red before falling in the autumn making this a great late summer choice for front of a border.
- Flowers from July to August
- Hardy
- Grows to 80cm tall and 50cm wide
- Well-drained soil
- Sun to part shade
- Exposed
Fun Fact
Not only is this plant striking in the garden, but it is good for the local wildlife too! The RHS have acknowledged it as a great Plant for Pollinators. In addition, it has the RHS Award of Garden Merit!
6. Sorbus aucuparia (Rowan)
Rowans are conical shape trees that cope extremely well with harsh conditions, hence their other common name of ‘Mountain Ash’. At this time of year, the berries turn a bright shade of orange/red and are much loved by birds making this an ideal choice for a wildlife-friendly garden.
- Flowers from April to May
- Hardy
- Grows to 12m tall and 5m wide
- Well-drained soil
- Sun to part shade
- Exposed
Fun Fact
Rowan trees have quite a mystical history! They have been grown historically near houses thanks to their suspected protection against witches. This was because the colour red was thought the best for protection against evil.
This is a more compact form of the other ‘Annabelle’ hydrangeas and is covered in clusters of deep pink flowers at this time of year. It can be grown in a large container or planted mid-border. It has the added advantage of being happy growing in the sun as well as light shade.
- Flowers from July to September
- Hardy
- Grows to 120cm tall and 120cm wide
- Moist but well-drained, rich soil
- Sun to part shade
- Exposed
Top Tip
Hydrangeas generally don’t like drying out. Water well and regularly to help your Hydrangea to look its best.
8. Buddleja ‘Little Purple’ (Butterfly bush)
Unlike most buddleja, this cultivar is an extremely compact size. This makes it ideal for people with a small growing space who want to attract pollinating insects. It produces clusters of high-in-nectar, rich purple flowers which butterflies find irresistible!
- Flowers from July to September
- Hardy
- Grows to 80cm tall and 80cm wide
- Moist, well-drained, moderately fertile soil
- Full sun
- Exposed
Fun Fact
Unsurprisingly, this plant is popular with butterflies. So popular, in fact, that naturalist Richard Mabey saw 50 individual butterflies on his Buddleja at the same time in August.
9. Miscanthus sinensis ‘Flamingo’ (Silver grass)
Late summer is the time of the year when Many grasses start to flower and ‘Flamingo’ is no exception, producing arching plumes of tan-pink flowers above clumps of narrow, arching, mid-green colour leaves. Very hardy and long-lived, it’s a great choice for back of a border.
- Flowers from August to September
- Hardy
- Grows to 120cm tall and 75cm wide
- Well-drained soil
- Sun to part shade
- Exposed
Top Tip
Silver grass is a great choice for many garden styles. Particularly, they are perfect for coastal gardens, city gardens, cottage gardens, or prairie planting!
10. Phlox x arendsii ‘Hesperis’ (Phlox)
This is one of the last phlox to come into flower making it a great choice for the August flower garden as it will continue flowering well into September! It produces tall clusters of heavily scented, small, lilac flowers on strong stems that rarely need staking.
- Flowers from July to September
- Hardy
- Grows to 80cm tall and 50cm wide
- Well-drained soil
- Sun to part shade
- Exposed
Top Tip
The blooms of Phlox are particularly wildlife friendly. Pollinators love them, thanks to the flowers providing easy access. Plus, this variety being purple makes the especially attractive to bees, as they see purple better than any other colour.
These wonderful plants will perfectly brighten up your garden this August.
Find out about some more of my favourite and most interesting plants:
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David Domoney is a Chartered Horticulturalist, Broadcaster, and Author. David has worked with a number of the UK’s leading garden retailers as a plant buyer and strategic consultant. With more than 30 years experience, in horticulture, David is as passionate about plants now as he was when he bought his first plant at a village fete.
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