Best Summer Flowers for UK Gardens: 25 Beautiful Plants

Summer is one of the most exciting times of year in the garden, with colourful flowers filling borders, containers, hanging baskets and allotments.

From spectacular dahlias and cheerful marigolds to delicate cosmos, beautiful roses and long-flowering salvias, there are countless plants that can transform your garden during the warmer months.

One of the biggest advantages of growing summer flowers is the enormous variety available.

Some plants produce large, dramatic blooms that create spectacular displays.

Others produce hundreds of smaller flowers, providing colour over several months.

Many summer flowers are also excellent for attracting bees, butterflies, hoverflies and other beneficial insects.

This makes them particularly valuable for gardeners who want to create wildlife-friendly spaces.

Here at Gardening with Ben, I enjoy growing a wide range of summer flowers around the garden and allotment.

After spending spring sowing seeds, planting young plants and preparing flower borders, it’s wonderful to see everything bursting into colour.

Summer flowers are also excellent for filling gaps between vegetables, brightening pathways and providing cut flowers for the home.

However, not all summer flowers have the same growing requirements.

Some prefer full sun and relatively dry conditions.

Others perform best in fertile, moisture-retentive soil.

Some are hardy perennials that return every year, while others are tender annuals that need replacing or growing from seed.

In this complete UK gardening guide, we’ll explore 25 of the best summer flowers to grow.

We’ll cover flowering times, growing conditions, planting advice, container growing, watering, feeding, deadheading and how to keep your garden colourful from June through September.

What Are Summer-Flowering Plants?

Summer-flowering plants are plants that produce their main displays during the warmer months.

In the UK, summer is generally considered to run from June through August.

However, many summer flowers begin blooming during May and continue into September or October.

Annual Summer Flowers

Annuals complete their life cycle within one growing season.

Examples include cosmos, zinnias and many marigolds.

Perennial Summer Flowers

Perennials return for multiple years when grown in suitable conditions.

Examples include echinacea, rudbeckia, hardy geraniums and many salvias.

Summer-Flowering Bulbs and Tubers

Some plants grow from bulbs, corms or tubers.

Examples include dahlias, gladioli and lilies.

Summer Bedding Plants

These are commonly grown for colourful seasonal displays.

Examples include petunias, begonias and pelargoniums.

Why Grow Summer Flowers?

Summer flowers offer numerous benefits.

Beautiful Colour

They brighten borders, containers and patios.

Long Flowering Seasons

Some varieties flower for several months.

Wildlife Benefits

Many attract bees, butterflies and other beneficial insects.

Cut Flowers

Numerous varieties are suitable for cutting.

Suitable for Small Gardens

Many grow well in containers.

Excellent for Allotments

Flowers can provide colour alongside vegetables.

Wide Variety

There are flowers suitable for different garden styles and growing conditions.

25 Best Summer Flowers for UK Gardens

1. Dahlias

Dahlias are among the most spectacular summer-flowering plants.

They produce flowers in an enormous range of shapes, sizes and colours.

When Do Dahlias Flower?

Usually July through October, continuing until significant frost.

Best Position

Full sun.

Soil

Fertile, moisture-retentive but well-drained.

Best Uses

Borders, containers and cut-flower gardens.

Gardening with Ben Tip

Deadhead regularly to encourage continued flowering.

2. Cosmos

Cosmos produces beautiful daisy-like flowers on delicate, feathery foliage.

Flower Colours

Pink, white, purple and crimson shades.

When Does Cosmos Flower?

Usually July through October, depending on sowing time and weather.

Best Position

Full sun.

Soil

Well-drained soil that isn’t excessively rich.

Why Grow It?

Cosmos is easy to grow from seed and provides long-lasting flowers.

Gardening with Ben Tip

Avoid excessive nitrogen fertiliser because it can encourage foliage instead of flowers.

3. Marigolds

Marigolds are cheerful summer flowers.

They produce bright yellow, orange and red-toned blooms.

Popular Types

French marigolds and African marigolds.

When Do Marigolds Flower?

Usually June through October.

Best Position

Full sun.

Soil

Well-drained.

Why Grow Them?

They’re excellent for borders, containers and vegetable gardens.

Gardening with Ben Tip

Plant marigolds around vegetable-growing areas for colourful displays that also attract visiting insects.

4. Zinnias

Zinnias produce bold, colourful flowers.

They’re particularly popular for cutting gardens.

Flower Colours

Red, pink, orange, yellow, white and purple.

When Do Zinnias Flower?

Usually July through September or October.

Best Position

Full sun.

Soil

Fertile, well-drained.

Why Grow Them?

Excellent for colourful summer displays.

Gardening with Ben Tip

Grow zinnias in a warm, sheltered position.

5. Sunflowers

Sunflowers are among the most recognisable summer flowers.

They produce large, cheerful flower heads.

Flower Colours

Yellow, orange, red and bronze shades.

When Do Sunflowers Flower?

Usually July through September.

Best Position

Full sun.

Soil

Fertile, well-drained.

Why Grow Them?

Sunflowers provide spectacular colour and can attract pollinating insects.

Gardening with Ben Tip

Choose branching varieties if you want several flowers rather than one large flower head.

6. Echinacea

Echinacea is commonly known as coneflower.

It produces beautiful daisy-like flowers with raised central cones.

Flower Colours

Purple, pink, white, orange and yellow.

When Does Echinacea Flower?

Usually July through September.

Best Position

Full sun.

Soil

Well-drained.

Why Grow It?

Excellent for wildlife-friendly perennial borders.

Gardening with Ben Tip

Leave some seed heads standing during autumn and winter for birds.

7. Rudbeckia

Rudbeckias produce bright yellow and orange flowers.

Their dark central cones create beautiful contrast.

When Do Rudbeckias Flower?

Usually July through October.

Best Position

Full sun.

Soil

Fertile, well-drained.

Why Grow Them?

They’re excellent for late-summer colour.

Gardening with Ben Tip

Rudbeckia ‘Goldsturm’ is a reliable perennial variety.

8. Salvias

Salvias are among the best long-flowering plants for UK gardens.

Their flowers are available in shades of purple, blue, pink and red.

When Do Salvias Flower?

Depending on variety, late spring through autumn.

Best Position

Full sun.

Soil

Well-drained.

Popular Varieties

Salvia ‘Amistad’, Salvia ‘Hot Lips’ and Salvia nemorosa ‘Caradonna’.

Gardening with Ben Tip

Check winter hardiness because some salvias need frost protection.

9. Lavender

Lavender is a beautiful aromatic plant.

It produces fragrant flower spikes that attract bees.

When Does Lavender Flower?

Usually June through August, depending on variety.

Best Position

Full sun.

Soil

Well-drained.

Why Grow It?

Excellent for pollinators and scented borders.

Gardening with Ben Tip

Avoid planting lavender in persistently wet soil.

10. Roses

Roses are among the most popular garden flowers.

They produce beautiful blooms in numerous colours and forms.

When Do Roses Flower?

Many modern repeat-flowering varieties bloom from June into autumn.

Best Position

Full sun.

Soil

Fertile, moisture-retentive but well-drained.

Why Grow Them?

Excellent for cottage gardens and ornamental borders.

Gardening with Ben Tip

Choose repeat-flowering varieties for colour over a longer period.

11. Sweet Peas

Sweet peas produce beautiful, often fragrant flowers.

They’re excellent climbing plants for summer gardens.

When Do Sweet Peas Flower?

Usually June through August, sometimes longer.

Best Position

Full sun.

Soil

Fertile, moisture-retentive but well-drained.

Why Grow Them?

Excellent for fragrant cut flowers.

Gardening with Ben Tip

Pick flowers regularly to discourage seed pod production and extend flowering.

12. Petunias

Petunias are among the most popular summer bedding plants.

They produce colourful flowers throughout summer.

Flower Colours

Pink, purple, red, white, yellow and mixed shades.

When Do Petunias Flower?

Usually late spring through autumn.

Best Position

Full sun.

Soil

Suitable well-drained compost.

Why Grow Them?

Excellent for hanging baskets, pots and containers.

Gardening with Ben Tip

Feed container-grown petunias according to their needs to maintain flowering.

13. Begonias

Begonias are excellent for summer containers and bedding displays.

Flower Colours

Red, pink, orange, yellow and white.

When Do Begonias Flower?

Usually June through October.

Best Position

Depends on variety; many tolerate partial shade.

Soil

Moisture-retentive but well-drained.

Why Grow Them?

Excellent for adding colour to partially shaded areas.

Gardening with Ben Tip

Choose varieties suited to your garden’s light conditions.

14. Geraniums and Pelargoniums

Pelargoniums are commonly sold as bedding geraniums.

They’re different from hardy garden geraniums.

Flower Colours

Red, pink, white, purple and salmon shades.

When Do They Flower?

Usually late spring through autumn.

Best Position

Full sun.

Soil

Well-drained.

Why Grow Them?

Excellent for patio pots and summer containers.

Important Advice

Most bedding pelargoniums are frost tender.

15. Hardy Geraniums

Hardy geraniums are reliable perennial plants.

Popular Variety

Geranium ‘Rozanne’.

Flower Colours

Blue, purple, pink and white.

When Do They Flower?

Depending on variety, late spring through autumn.

Best Position

Full sun or partial shade.

Soil

Moisture-retentive but well-drained.

Why Grow Them?

Excellent for filling gaps in borders.

Gardening with Ben Tip

Geranium ‘Rozanne’ is particularly useful for a long flowering season.

16. Verbena bonariensis

Verbena bonariensis produces tall stems topped with clusters of purple flowers.

When Does It Flower?

Usually July through October.

Best Position

Full sun.

Soil

Well-drained.

Why Grow It?

Excellent for butterflies and bees.

Gardening with Ben Tip

Plant among other perennials to create height without blocking the view.

17. Gaura

Gaura produces delicate white or pink flowers on slender stems.

It’s also known botanically as Oenothera lindheimeri.

When Does It Flower?

Usually June through October.

Best Position

Full sun.

Soil

Well-drained.

Why Grow It?

Creates a beautiful airy effect in borders.

Gardening with Ben Tip

Avoid waterlogged winter soil.

18. Penstemons

Penstemons produce colourful tubular flowers.

Flower Colours

Pink, purple, red, blue and white.

When Do Penstemons Flower?

Usually June through October.

Best Position

Full sun.

Soil

Well-drained.

Why Grow Them?

Excellent for long-lasting summer colour.

Gardening with Ben Tip

Take cuttings of less hardy varieties as insurance against winter losses.

19. Foxgloves

Foxgloves produce tall flower spikes covered in tubular blooms.

Botanical Name

Digitalis.

Flower Colours

Pink, purple, white and yellow shades.

When Do Foxgloves Flower?

Many common varieties flower during May through July.

Best Position

Partial shade or sun with suitable moisture.

Soil

Moisture-retentive but well-drained.

Why Grow Them?

Excellent for cottage gardens and bumblebees.

Important Safety Advice

All parts of foxgloves are poisonous if eaten.

20. Delphiniums

Delphiniums produce spectacular tall flower spikes.

Flower Colours

Blue, purple, pink and white.

When Do Delphiniums Flower?

Usually June through July, with possible repeat flowering.

Best Position

Full sun.

Soil

Fertile, moisture-retentive but well-drained.

Why Grow Them?

Excellent for traditional cottage gardens.

Gardening with Ben Tip

Provide support for tall flower spikes.

21. Lupins

Lupins produce colourful upright flower spikes.

Flower Colours

Purple, pink, blue, yellow, red and white.

When Do Lupins Flower?

Usually May through July, sometimes with a later flush.

Best Position

Full sun or light shade.

Soil

Well-drained.

Why Grow Them?

Excellent for adding height and colour.

Gardening with Ben Tip

Protect young shoots from slugs and snails.

22. Hydrangeas

Hydrangeas are among the most popular summer-flowering shrubs.

Flower Colours

Pink, blue, purple, white and green shades.

When Do Hydrangeas Flower?

Usually June through September, depending on variety.

Best Position

Partial shade, although some tolerate sun with adequate moisture.

Soil

Moisture-retentive but well-drained.

Why Grow Them?

Excellent for large, impressive flower displays.

Gardening with Ben Tip

Water during prolonged dry weather.

23. Phlox paniculata

Garden phlox produces clusters of fragrant flowers.

Flower Colours

Pink, purple, white and red shades.

When Does Phlox Flower?

Usually July through September.

Best Position

Full sun or light shade.

Soil

Fertile, moisture-retentive but well-drained.

Why Grow It?

Excellent for colourful cottage garden borders.

Gardening with Ben Tip

Maintain good airflow to reduce powdery mildew problems.

24. Gladioli

Gladioli produce tall flower spikes with large, colourful blooms.

Flower Colours

Red, pink, purple, yellow, orange and white.

When Do Gladioli Flower?

Usually July through September.

Best Position

Full sun.

Soil

Well-drained.

Why Grow Them?

Excellent for cutting gardens.

Gardening with Ben Tip

Plant corms in batches during spring to extend flowering.

25. Calendula

Calendula, commonly known as pot marigold, is an easy annual flower.

Flower Colours

Yellow and orange.

When Does Calendula Flower?

Usually late spring through autumn.

Best Position

Full sun or light shade.

Soil

Well-drained.

Why Grow It?

Excellent for beginners and wildlife-friendly gardens.

Gardening with Ben Tip

Allow some plants to self-seed for future displays.

Best Summer Flowers by Month in the UK

Month	Flowers to look for
June	Roses, lavender, sweet peas, foxgloves, lupins, delphiniums, petunias
July	Dahlias, cosmos, sunflowers, echinacea, rudbeckias, salvias, zinnias
August	Dahlias, cosmos, zinnias, salvias, rudbeckias, verbena, phlox
September	Dahlias, cosmos, rudbeckias, salvias, penstemons, calendula

Flowering times vary depending on weather, variety and location.

Best Summer Flowers That Bloom for Months

If you’re looking for flowers that provide colour over a long period, several plants are particularly useful.

Cosmos

Flowers from summer until frost.

Dahlias

Produce repeated flowers when deadheaded.

Salvias

Many varieties flower for several months.

Petunias

Excellent for long-lasting container colour.

Hardy Geranium ‘Rozanne’

Produces flowers over an extended season.

Penstemons

Many varieties flower through summer and into autumn.

Verbena bonariensis

Excellent for late-summer and autumn colour.

Calendula

Can flower over a long period when conditions are suitable.

Best Summer Flowers for Pots

Containers are excellent for colourful summer displays.

Suitable Plants

• Petunias
• Begonias
• Pelargoniums
• Compact dahlias
• Marigolds
• Zinnias
• Salvias
• Cosmos
• Lavender
• Compact roses

Choosing a Pot

Select a container with drainage holes.

Compost

Use suitable peat-free compost.

Position

Choose somewhere with appropriate sunlight.

Watering

Check moisture regularly during warm weather.

Feeding

Container-grown plants often benefit from suitable feeding during active growth.

How to Create a Colourful Summer Container

Step 1: Choose a Suitable Pot

Select a container with drainage holes.

Step 2: Add Compost

Use suitable peat-free compost.

Step 3: Choose a Main Plant

A compact dahlia or salvia can provide structure.

Step 4: Add Colourful Bedding

Include petunias, marigolds or begonias.

Step 5: Add Trailing Plants

Choose suitable trailing varieties where desired.

Step 6: Arrange Plants

Allow sufficient space for healthy growth.

Step 7: Water Thoroughly

Water after planting.

Step 8: Position the Container

Choose somewhere suitable for the plants.

Step 9: Feed During Growth

Use appropriate fertiliser.

Step 10: Deadhead Regularly

Remove faded flowers to maintain the display.

Best Summer Flowers for Hanging Baskets

Hanging baskets are excellent for adding colour to patios, entrances and fences.

Petunias

Popular for trailing displays.

Trailing Begonias

Excellent for partially shaded positions.

Trailing Pelargoniums

Suitable for sunny positions.

Lobelia

Produces delicate flowers in blue, purple and white.

Bacopa

Produces numerous small flowers.

Fuchsias

Excellent for hanging baskets in suitable light conditions.

Important Advice

Hanging baskets can dry out quickly during hot weather.

Check moisture frequently.

Best Summer Flowers for Shady Gardens

Not every garden receives full sunlight.

Fortunately, several summer flowers tolerate shade.

Begonias

Many varieties grow well in partial shade.

Fuchsias

Often perform well in sheltered partial shade.

Hydrangeas

Many prefer partial shade.

Hardy Geraniums

Some varieties tolerate shade.

Foxgloves

Excellent for lightly shaded borders.

Japanese Anemones

Useful for late-summer colour in partial shade.

Important Advice

Deep shade limits flowering options.

Choose plants according to the amount of light available.

Best Summer Flowers for Sunny Gardens

Sunny gardens offer numerous options.

Dahlias

Excellent for bold colour.

Cosmos

Beautiful airy flowers.

Zinnias

Bright, colourful blooms.

Sunflowers

Spectacular summer flowers.

Salvias

Long-lasting colour.

Lavender

Fragrant flowers.

Echinacea

Excellent for wildlife.

Rudbeckias

Cheerful yellow flowers.

Best Summer Flowers for Bees

Summer flowers can provide valuable nectar and pollen.

Lavender

Very attractive to bees.

Salvias

Excellent nectar plants.

Echinacea

Attractive to bees and butterflies.

Rudbeckia

Useful for pollinating insects.

Verbena bonariensis

Popular with butterflies.

Sunflowers

Pollen-rich varieties can attract bees.

Calendula

Useful for pollinators.

Cosmos

Single-flowered varieties can provide accessible pollen and nectar.

Important Advice

Choose a variety of flower shapes and flowering periods.

When Should You Plant Summer Flowers in the UK?

Planting times vary depending on the plant.

February

Some summer flowers can be started indoors with suitable warmth and light.

March

An excellent month for sowing many annual flowers indoors.

April

Continue seed sowing and plant suitable hardy perennials.

May

Harden off tender plants and plant outdoors after frost risk.

June

A suitable month for planting many tender summer bedding plants.

July

Container-grown plants can be planted if watered carefully.

Best Advice

Don’t plant frost-tender flowers outdoors before the risk of frost has passed.

How to Keep Summer Flowers Blooming Longer

Several simple steps help extend flowering.

Deadhead Regularly

Remove faded flowers from plants that benefit.

Water During Dry Weather

Avoid severe drought stress.

Feed Container Plants

Use suitable fertiliser during active growth.

Avoid Excessive Nitrogen

Too much nitrogen can encourage foliage rather than flowers.

Provide Enough Sunlight

Many summer flowers need full sun.

Support Tall Plants

Stake dahlias, delphiniums and other tall flowers.

Remove Seed Pods

For plants such as sweet peas, removing seed pods can encourage continued flowering.

Choose Repeat-Flowering Varieties

Some plants naturally flower for longer than others.

How Often Should You Water Summer Flowers?

Watering depends on plant type, soil and weather.

Newly Planted Flowers

Water regularly while roots establish.

Established Perennials

Many tolerate short dry spells.

Container-Grown Flowers

Pots often require more frequent watering.

Hanging Baskets

These may need daily checks during hot weather.

Drought-Tolerant Flowers

Some established plants need less watering.

Best Advice

Check soil moisture rather than following a fixed watering schedule.

Do Summer Flowers Need Feeding?

Some summer flowers benefit from additional feeding.

Garden Borders

Plants growing in fertile soil may need little extra fertiliser.

Containers

Potted plants often benefit from feeding.

Flowering Fertiliser

Suitable high-potassium fertiliser can support flowering.

Avoid Overfeeding

Excess fertiliser can damage plants or encourage excessive foliage.

Best Advice

Follow product instructions and adjust feeding according to plant needs.

Common Summer Flower Problems

Slugs and Snails

May damage young plants.

Aphids

Can gather on tender shoots.

Powdery Mildew

May affect some flowers during warm, dry conditions.

Drought Stress

Can reduce flowering.

Waterlogging

Can damage roots.

Wind Damage

Tall flowers may need support.

Poor Flowering

Insufficient sunlight or excessive nitrogen may be responsible.

Prevention

Choose suitable growing positions and inspect plants regularly.

Best Summer Flowers for an Allotment

Summer flowers are excellent for adding colour to allotments.

Around the Shed

Plant dahlias, cosmos and sunflowers.

Cutting Gardens

Grow sweet peas, zinnias, gladioli and dahlias.

Wildlife Areas

Include lavender, salvias, echinacea and Verbena bonariensis.

Raised Beds

Use suitable compact annual flowers.

Pathway Edges

Plant calendula, marigolds and hardy geraniums.

Important Advice

Avoid placing tall flowers where they may shade vegetable crops unnecessarily.

How to Plan a Garden That Flowers All Summer

The best approach is to combine plants with different flowering periods.

Early Summer

Choose roses, lavender, foxgloves, lupins and sweet peas.

Mid-Summer

Include dahlias, cosmos, zinnias, salvias and echinacea.

Late Summer

Add rudbeckias, penstemons, phlox and Verbena bonariensis.

Early Autumn

Continue with dahlias, cosmos, salvias and calendula.

Best Advice

Combining annuals, perennials and bulbs creates a much longer flowering season.

Frequently Asked Questions About Summer Flowers

What Are the Best Summer Flowers for UK Gardens?

Dahlias, cosmos, marigolds, zinnias, salvias, roses and rudbeckias are excellent choices.

What Flowers Bloom in June?

Roses, lavender, sweet peas, foxgloves and lupins.

What Flowers Bloom in July?

Dahlias, cosmos, zinnias, echinacea and salvias.

What Flowers Bloom in August?

Dahlias, cosmos, rudbeckias, salvias and phlox.

What Flowers Bloom All Summer?

Many salvias, petunias, cosmos and repeat-flowering roses can bloom over an extended period.

What Are the Easiest Summer Flowers to Grow?

Calendula, marigolds, cosmos and sunflowers are excellent choices.

What Summer Flowers Grow from Seed?

Cosmos, zinnias, sunflowers, marigolds and calendula.

What Summer Flowers Come Back Every Year?

Echinacea, rudbeckia, hardy geraniums, lavender and many salvias.

What Summer Flowers Are Best for Pots?

Petunias, begonias, pelargoniums, marigolds and compact dahlias.

What Summer Flowers Grow in Shade?

Begonias, fuchsias, hydrangeas and some hardy geraniums.

What Summer Flowers Need Full Sun?

Dahlias, cosmos, zinnias, sunflowers and lavender.

What Summer Flowers Are Good for Bees?

Lavender, salvias, echinacea, rudbeckia and Verbena bonariensis.

When Should You Plant Summer Flowers?

Many tender flowers are planted outdoors after the final spring frost.

Can You Plant Summer Flowers in May?

Yes, once frost risk has passed for tender varieties.

Can You Plant Summer Flowers in June?

Yes.

Do Summer Flowers Need Feeding?

Some benefit from feeding, particularly container-grown plants.

How Often Should You Water Summer Flowers?

Water according to soil moisture, weather and plant requirements.

Should You Deadhead Summer Flowers?

Many varieties benefit from regular deadheading.

Why Are My Summer Flowers Not Blooming?

Insufficient sunlight, excessive nitrogen or unsuitable growing conditions may be responsible.

Can Summer Flowers Survive Frost?

Hardiness varies. Many summer bedding plants are frost tender.

Are Dahlias Perennials?

Yes, but their tubers may need winter protection.

Are Cosmos Perennials?

Common garden cosmos are generally grown as annuals in the UK.

Are Marigolds Annuals?

Most commonly grown French and African marigolds are annuals.

Do Salvias Flower All Summer?

Many varieties flower over a long period.

Can You Grow Summer Flowers in Hanging Baskets?

Yes. Petunias, begonias, lobelia and fuchsias are excellent choices.

Can You Grow Summer Flowers on an Allotment?

Yes. They’re excellent for cutting gardens, wildlife areas and ornamental borders.

Final Thoughts: Growing Beautiful Summer Flowers in the UK

Summer is a wonderful season for enjoying colourful flowers in your garden or allotment.

With so many varieties available, it’s possible to create beautiful displays from June through September and beyond.

Dahlias, cosmos, marigolds, zinnias, salvias and rudbeckias are among the best choices for long-lasting summer colour.

For the best results, choose flowers suited to your garden’s sunlight, soil and growing conditions.

Combine annuals and perennials to create a varied display.

Deadhead suitable plants regularly and water during prolonged dry weather.

Container-grown flowers may also benefit from additional feeding.

One of the most important things to remember is to plan for different flowering periods.

Early-summer flowers such as roses and lavender can be followed by dahlias, cosmos, echinacea and rudbeckias later in the season.

And don’t forget the wildlife benefits.

Many summer flowers provide valuable nectar and pollen for bees, butterflies and other beneficial insects.

Whether you’re growing flowers in patio pots, hanging baskets, cottage garden borders or around your allotment, summer is the perfect time to enjoy everything you’ve planted.

Keep smiling, keep shining, keep gardening with Ben!