What Flowers to Plant in August UK

August might feel like the tail end of the gardening season, but there’s still plenty you can plant to extend colour and prepare for the months ahead. The days are still warm, the soil is soft and workable, and late-season planting can breathe new life into your garden. Whether you're hoping for a late burst of blooms or laying the groundwork for a spectacular spring, August offers a wealth of floral possibilities.

Why August Planting Works

While many annuals have already done their best work by August, it’s a brilliant time to sow biennials and hardy perennials. These plants need time to establish before the cold weather arrives, and if given that chance, they’ll reward you with robust growth and beautiful flowers next season. August is also ideal for freshening up tired beds with quick-growing annuals that still have time to bloom before the first frost.

Best Flowers to Plant in August UK

Wallflowers (Erysimum) are a go-to choice for planting in August. These biennials thrive when planted in late summer, building strength through autumn and flowering in spring with a wonderful scent and splash of colour.

Sweet William (Dianthus barbatus) can still be planted now to ensure a show-stopping border display next year. The frilled flowers in rich shades of red, pink and white are a traditional favourite.

Foxgloves (Digitalis) are another classic that does well when planted in August. These tall, elegant spires prefer partial shade and are a magnet for pollinators when they bloom the following year.

Forget-Me-Nots (Myosotis) are ideal for naturalising under shrubs or around the edges of borders. Sown or planted in August, they’ll flower in spring and often self-seed for the future.

Pansies and Violas are versatile bedding plants that can be sown now for autumn and winter colour, especially in milder regions or protected pots. They’ll flower through the cooler months and bounce back again in spring.

Aquilegia (Columbine) is a lovely perennial to add in August. With delicate, nodding flowers in spring, it naturalises easily and is happy in borders or under trees.

Primroses and Polyanthus benefit from late summer planting, allowing them to settle before blooming in early spring. These low-growing flowers are perfect for edging paths or filling gaps in flowerbeds.

Planting for Immediate and Future Colour

Although most quick-flowering summer annuals are past their peak by August, some hardy types such as Calendula and Cornflowers can still be planted for a last flush of colour if the weather stays mild. Otherwise, the focus shifts to setting up next year’s floral displays, especially with spring-flowering favourites.

August is also a smart time to divide established perennials such as Phlox, Geraniums, or Shasta daisies and replant the divisions elsewhere in the garden. This keeps plants healthy and allows for a more evenly spaced display next season.

Care Tips for August Planting

Keep newly planted flowers well-watered during dry spells and add mulch to help retain moisture. It’s also important to keep an eye on pests like slugs and snails, which are still active and may target young plants. Feeding with a gentle liquid fertiliser can give your plants a boost and help them establish more quickly.

Whether you're planting for now or for the future, August is far from the end of the gardening season. With a little planning, this late summer window can set the stage for months of blooming success.

August is a Month for Preparation

While most of the high-summer planting frenzy has passed, August is when forward-thinking gardeners start laying the groundwork for spring and early summer colour. Many of the flowers planted now won’t bloom straight away, but they’ll establish healthy root systems ready for when the weather warms again.

Focus on Biennials and Hardy Perennials

August is perfect for sowing biennials like Wallflowers, Foxgloves and Sweet William. These plants grow leaves in the first year, overwinter quietly and then burst into flower the following spring or summer. It's a great way to ensure your garden gets an early start next year.

Hardy perennials like Lupins, Aquilegia and Delphiniums can also go in the ground now. The warm soil helps them settle in quickly and get a head start before winter arrives.

Keep an Eye on the Weather

August can swing from blazing hot days to cooler spells with rain, so flexibility is key. Water any new plants thoroughly, especially during dry spells, and consider using mulch to retain moisture. If it’s particularly hot, planting early in the morning or late in the day will help reduce transplant shock.

You Can Still Sneak in Some Quick Growers

Although the main sowing season for summer annuals is behind us, you can still pop in some quick-growing varieties like Calendula, Cornflowers, or even Nasturtiums if your local climate allows. These might give you a small show of late colour before the frosts arrive.

Great Time for Dividing and Rejuvenating

August is also a good time to divide mature perennials. Plants like Daylilies, Irises, and Hostas benefit from being lifted, split and replanted now. This keeps them healthy and helps spread colour around your garden. It’s also a chance to tidy up any straggly or overcrowded areas before autumn sets in.

A Boost for Wildlife-Friendly Gardening

Many of the flowers planted in August are pollinator magnets. Foxgloves, Erysimum, Aquilegia and Forget-Me-Nots all attract bees and butterflies when they flower. By planting them now, you’re not just preparing for visual beauty but helping local wildlife too.

Consider Your Soil and Space

This is a great time to look critically at your borders. Are there gaps? Are some areas tired or overgrown? August planting can help you refresh those spaces. It's also a good month to work on improving your soil with compost or well-rotted manure before new planting.

Use Containers for Flexibility

If you’re not quite sure where to put something, try planting in pots. Many August-friendly flowers do well in containers, especially Pansies, Violas, and Primroses. You can move them about to catch the best light or create instant autumn-winter displays on patios and doorsteps.

List of Flowers to Plant in August UK

• Wallflowers (Erysimum) – biennials for spring colour

• Sweet William (Dianthus barbatus) – colourful clusters for next year

• Foxgloves (Digitalis) – tall spires to bloom the following summer

• Forget-Me-Nots (Myosotis) – spring flowers ideal for shady spots

• Pansies and Violas – for winter bedding and early colour

• Aquilegia (Columbine) – cottage garden favourite for spring

• Primroses and Polyanthus – classic early bloomers

• Calendula – hardy annuals for late summer interest

• Cornflowers (Centaurea cyanus) – fast-growing annuals

• Lupins – perennials that benefit from a head start now

• Delphiniums – late summer planting for tall displays next year

Final Thoughts:

August isn’t the end of the gardening season—it’s a smart moment to plan ahead. While many summer annuals are winding down, this month offers the perfect window to plant hardy perennials and biennials that will reward you next spring. With warm soil and manageable weather, new plants can establish strong roots before winter. Whether you’re refreshing tired borders or prepping for a bold spring display, planting in August keeps your garden thriving. A little effort now means months of colour later.