22 Best Summer Garden Flowers To Plant In May And June | dahlias, Marigolds, And Gladiolus!

May and June are the best months to plan and plant your summer flower garden in many US growing zones. As frost threats recede and soil warms, these months offer ideal conditions to establish flowers that thrive through summer’s heat. Each entry in this list of the best flowers to plant in May and June creates visual splendor. These flowers will transform your outdoor space into a buzzing pollinator sanctuary and are truly a wonder to behold!

Beautiful pink purple and white cosmos flowers.

Sound intriguing?

Then let’s plant some summer flowers!

22 Best Summer Flowers To Plant In May Or June

There are countless beautiful flowers you can plant successfully in May and June. But of all summertime flowers, these 22 are our favorites.

1. Dahlias

Lovely bouquet of colorful dahlia flowers.

Dahlias are the showstoppers of summer gardens, bursting with dinner-plate-sized blooms in nearly every color imaginable. They thrive when planted after the last frost, rewarding gardeners with continuous blooms that make extraordinary cut flowers.

USDA Grow Zone: 8 to 11 (grown annually in cooler zones).
Best Time To Plant: After last frost, late spring to early summer (May to June).
Bloom Time: Midsummer to first frost.
Flower Color: Pink, red, yellow, white, purple, orange, and more.
Plant Size: 1 to 5 feet tall.

While dahlias don’t offer much fragrance, their spectacular visual impact and long vase life more than compensate.

2. Zinnias

Colorful radiant zinnia flowers growing in the garden.

These cheerful, no-fuss flowers are summer garden champions, blooming profusely within weeks of planting. Zinnias attract butterflies and bees while standing up beautifully to summer heat and drought.

USDA Grow Zone: 2 to 11 (grown as annuals).
Best Time To Plant: After the last spring frost, typically late April to June.
Bloom Time: Late spring to first frost.
Flower Color: Red, pink, orange, yellow, white, and purple.
Plant Size: 1 to 3 feet tall.

Zinnias have stunning candy-colored blooms on sturdy stems that are perfect for cutting and butterfly gardens!

3. Marigolds

Beautiful Aztec marigold plant with orange and yellow flowers.

These bright yellow and orange workhorses are your garden’s best defenders, with a distinctive scent that naturally repels many garden pests. Marigolds are practically bulletproof. They thrive in hot, sunny conditions that would wilt lesser plants.

USDA Grow Zone: 2 to 11 (grown as annuals).
Best Time To Plant: After the last frost date in spring, around May to June.
Bloom Time: Late spring to frost.
Flower Color: Orange, yellow, red, and bicolor.
Plant Size: Roughly 6 inches to 3 feet tall.

Edible marigold petals add a splash of color to summer salads. And their roots help improve soil health wherever they grow!

4. Sunflowers

Lovely but slightly wilted sunflowers growing in the hot summer.

Few garden pleasures are as intriguing as watching sunflowers and their big flower heads track the sun across the sky. Beyond being garden showpieces, they’re ecological powerhouses, feeding birds and bees and yielding delicious seeds for your pantry.

USDA Grow Zone: 4 to 9.
Best Time To Plant: After the last spring frost (May to June).
Bloom Time: Summer to early fall (July to September).
Flower Color: Yellow, orange, red, brown, and bicolor.
Plant Size: 2 to 10+ feet tall.

Plant sunflowers along fences or as a walkway and garden interest so everyone can enjoy their towering heights.

5. Coneflowers (Echinacea)

Pinkish purple coneflowers growing in the native plant garden.

These native prairie flowers combine stunning good looks with serious medicinal properties. Coneflowers bloom for months with minimal care. Their distinctive cone-shaped centers create architectural interest even in winter.

USDA Grow Zone: 3 to 9.
Best Time To Plant: Spring, around May.
Bloom Time: June to October.
Flower Color: Purple, pink, white, yellow, and orange.
Plant Size: 2 to 4 feet tall.

Bees and butterflies aren’t the only ones who cherish coneflowers. Everyone loves this plant. Birds adore their seedheads. And herbalists treasure their immune-boosting properties.

6. Milkweed (Asclepias)

Monarch butterflies visiting a swamp milkweed flowering plant.

Growing milkweed goes far beyond garden aesthetics. It’s real-world conservation in action! These essential native plants are the only food source for monarch butterfly caterpillars and produce fascinating seed pods after their sweetly scented blooms fade.

USDA Grow Zone: 3 to 9.
Best Time To Plant: Late spring to early summer (May to June).
Bloom Time: June to August.
Flower Color: Pink, orange, white, and red.
Plant Size: 1 to 5 feet tall.

Plant milkweed in sunny borders where its structural seedpods can add winter interest.

7. Salvia

Lovely purple salvia flowers growing in the wild garden.

Salvias bring vertical intrigue to the garden with spiky flower wands that seem to bloom forever. Their aromatic foliage naturally deters deer and rabbits while attracting hungry hummingbirds by the boatload.

USDA Grow Zone: 4 to 10 (depending on species).
Best Time To Plant: After the last frost, late spring to early summer.
Bloom Time: Late spring to fall.
Flower Color: Blue, purple, red, pink, white.
Plant Size: 1 to 4 feet tall.

Salvias are drought-tolerant and heat-loving. They’re the perfect flowers for gardeners seeking low-maintenance, high-impact plants.

8. Verbena

Epic blooming purple verbena flowers growing in the garden.

Verbena flowers create carpets of color that spill over edges and soften hard landscaping. These sprawling beauties have beautifully clustered blooms with a refined texture in the garden. Remarkably resilient, they stand up well to summer’s worst heat waves, making them a reliable choice for vibrant, low-maintenance displays.

USDA Grow Zone: 7 to 11 (annual in cooler zones).
Best Time To Plant: Summer, once the heat sets in (June and after).
Bloom Time: Late spring through frost.
Flower Color: Purple, pink, red, white, and blue.
Plant Size: Roughly 6 inches to 3 feet tall.

Verbena flowers radiate a wonderfully subtle lemony scent. Their lovely aroma and butterfly-magnet status make them essential additions to sensory gardens.

9. Begonia

Watering some lovely begonia flowers in the garden.

Begonias bring tropical luxury to shady spots where few other flowers dare to bloom. Their waxy, often ruffled blossoms shed rain beautifully and come in sophisticated color palettes from apricot to deep crimson.

USDA Grow Zone: 9 to 11 (annual in cooler zones).
Best Time To Plant: Summer, after frost danger passes (June and after).
Bloom Time: Summer to fall.
Flower Color: White, pink, red, yellow, and orange.
Plant Size: About 6 inches to 2 feet tall.

Begonias are perfect for containers! Their tidy growth habit and continuous flowering also make them ideal for time-stretched gardeners.

10. Petunias

Colorful pink and white petunia flowers growing in the garden.

These garden classics have earned popularity through sheer flower power, producing wave after wave of trumpet-shaped blooms. Modern varieties bounce back quickly after rain and offer an intoxicating evening fragrance that perfumes entire patios.

USDA Grow Zone: Annual in zones 5 to 11. Thrives best in Zones 9 to 11.
Best Time To Plant: After the last frost, late spring (May).
Bloom Time: Spring to fall.
Flower Color: Purple, pink, red, white, yellow, blue.
Plant Size: Roughly 6 inches to one and a half feet tall.

The trailing habits of petunias also make them superb container plants for hanging baskets and window boxes.

11. Cosmos

Pink purple and red cosmos flowers growing in the garden.

Cosmos bring cottage garden charm with their daisy-like flowers dancing atop feathery foliage. They’re among the easiest flowers to grow from seed and thrive in poor soil where other plants struggle. They’re also wonderfully colorful and brighten nearly any garden.

USDA Grow Zone: 2 to 11 (grown as annuals).
Best Time To Plant: After the last frost, late spring to early summer (May to June).
Bloom Time: June to October.
Flower Color: Pink, white, red, orange, yellow.
Plant Size: 1 to 6 feet tall.

Cosmos flowers have delicate silhouettes that add movement and romantic appeal to your backyard planting scheme while requiring almost zero maintenance.

12. Gladiolus

Gorgeous and colorful gladioli flowers in the pollinator garden.

These dramatic sword-like blooms create vertical exclamation points in summer borders. Gladiolus corms (a type of bulb) also multiply annually, giving you more flowers each year with minimal investment.

USDA Grow Zone: 7 to 10 (dig up corms in cooler zones).
Best Time To Plant: Late spring to early summer (May to June).
Bloom Time: Mid to late summer (July to September).
Flower Color: Red, pink, yellow, white, purple, and more.
Plant Size: 2 to 5 feet tall.

Gladiolus has an old-fashioned charm that brings nostalgia to cutting gardens. They also offer heavy armloads of statuesque blooms for spectacular indoor arrangements.

13. Canna Lilies

Canna lily flowers growing in the garden.

Cannas deliver tropical intrigue with paddle-shaped leaves and bold flowers that keep raging all summer. Their architectural presence creates instant vacation vibes, with some varieties offering striking reddish burgundy or striped foliage.

USDA Grow Zone: 8 to 11 (dig up rhizomes in colder zones).
Best Time To Plant: After last frost, late spring to early summer (May to June).
Bloom Time: Mid to late summer through frost.
Flower Color: Red, orange, yellow, pink.
Plant Size: 3 to 6 feet tall.

Canna lilies are perfect for boggy areas or water garden margins where other plants might rot.

14. Gomphrena

Beautiful purple and white gomphrena flowers growing in the garden.

These everlasting flowers look like colorful clover blooms that never fade, keeping their vibrant hues even when dried. Gomphrena also shrugs off heat and drought while blooming continuously with zero deadheading required.

USDA Grow Zone: 9 to 11 (grown as annuals elsewhere).
Best Time To Plant: Summer, June or later.
Bloom Time: Mid to late summer to frost.
Flower Color: Purple, pink, red, white, and orange.
Plant Size: 1 to 2 feet tall.

Gomphrena’s globe-shaped flowers also make charming buttonholes and additions to dried arrangements that last for years.

15. Black-Eyed Susans

Black-Eyed Susan flowers growing in the urban meadow.

These sunny native wildflowers bring unstoppable cheer to summer gardens with their golden petals and distinctive dark centers. Black-Eyed Susans naturalize readily, creating drifts of color that return year after year with increased vigor.

USDA Grow Zone: 3 to 9.
Best Time To Plant: In late spring to early summer, when the soil reaches 70°F (May to June).
Bloom Time: June to September.
Flower Color: Yellow with dark brown or black centers.
Plant Size: 2 to 3 feet tall.

Black-Eyed Susan’s sturdy nature makes them a perfect partner for ornamental grasses in prairie-style plantings.

16. Alyssum

Lovely yellow alyssum flowers growing amidst a large rock.

Alyssum flowers pack a powerful, honey-sweet fragrance that seems impossible from such diminutive blooms. These tiny blooms create frothy white, purple, or pink carpets that soften garden edges and spill from containers.

USDA Grow Zone: 5 to 9.
Best Time To Plant: Roughly 1 or 2 weeks before the last frost. (April to May).
Bloom Time: Spring through summer, and sometimes into fall.
Flower Color: White, pink, purple, yellow.
Plant Size: 4 to 8 inches tall.

Alyssum’s ability to attract beneficial garden bugs, such as pollinators and predatory insects, makes it a superb companion for vegetable gardens and roses.

17. Ageratum

Lovely purple ageratum flowers growing in the summer garden.

These fluffy blue puffballs bring a rare true-blue color to your summer garden’s palette. Ageratum’s compact habit makes it perfect for edging beds or filling gaps between larger perennials.

USDA Grow Zone: 10 to 11 (grown as annuals elsewhere).
Best Time To Plant: On the last frost date or after, late spring (May to June).
Bloom Time: Late spring to frost.
Flower Color: Blue, lavender, pink, white.
Plant Size: Between 6 inches and 2 feet tall.

Ageratum’s velvety texture and cool hues contrast beautifully against hot-colored summer bloomers like zinnias and marigolds.

18. Roses

Lovely red or pink rose flowers blooming in the garden.

The queens of the garden have evolved far beyond their fussy reputation, with modern varieties offering disease resistance and repeat blooming. Summer-planted roses are also fast growers. They establish quickly in warm soil, often flowering within weeks of planting.

USDA Grow Zone: 4 to 9 (Varies by type. Some can also thrive in zone 3).
Best Time To Plant: Late spring to early summer (May to June).
Bloom Time: Late spring to fall (repeat bloomers).
Flower Color: All colors except true blue.
Plant Size: 1 to 6+ feet tall.

The incomparable fragrance and timeless beauty of rose gardens captivate the senses. This allure explains why humans have cultivated them for countless generations.

19. Lavender

Colorful flower bed with lavender flowers and orange marigold blooms.

This gorgeous Mediterranean herb combines stunning beauty with culinary and medicinal uses that have endured for centuries. Lavender’s greenish silvery foliage also looks gorgeous year-round, while its intensely aromatic flowers attract bees while repelling mosquitoes.

USDA Grow Zone: 5 to 9 (depends on species).
Best Time To Plant: Late spring (May).
Bloom Time: Around late spring to early summer. (May to July).
Flower Color: Purple, lavender, blue, white, pink.
Plant Size: 1 to 3 feet tall.

Plant lavender along pathways where brushing against it releases its majestic, calming scent on summer evenings.

20. Shasta Daisies

White Shasta Daisy flowers growing in the garden.

Shasta daisies bring crisp, clean elegance to summer borders with pristine petals and sunny centers. These classic white daisies also form generous clumps that can divide every few years to multiply your collection.

USDA Grow Zone: 5 to 9.
Best Time To Plant: Early spring or fall. (April and May work great.)
Bloom Time: June to September.
Flower Color: White petals with yellow centers.
Plant Size: 1 to 3 feet tall.

Shasta daisies have sturdy stems that rarely need staking, making them delightful low-maintenance options for cottage gardens.

21. Jacob’s Ladder

Beautiful Polemonium Caeruleum or Jacob's Ladder flowering shrub.

Jacob’s Ladder features delicate blue flowers floating above distinctive ladder-like foliage. This charming woodland plant thrives in partial shade where its superb coloration glows beautifully in dappled light.

USDA Grow Zone: 3 to 8.
Best Time To Plant: Early spring or fall. (April to May work great).
Bloom Time: Late spring to early summer (May to June).
Flower Color: Blue, purple, white.
Plant Size: 1 to 2 feet tall.

Jacob’s Ladder’s well-behaved growth habit makes it perfect for forest-edge gardens where it naturalizes politely without becoming invasive.

22. Big-Leaf Hydrangeas

Lovely pink hydrangea flowers growing in the garden.

These showstopping shrubs produce massive flower heads that shift color based on your soil’s pH. Expect blue in acidic soil, pink in alkaline soil. Hydrangeas planted in early summer quickly establish before winter dormancy, often blooming the following year.

USDA Grow Zone: 5 to 9.
Best Time To Plant: Spring or fall. (Try April or May).
Bloom Time: August to September. (Some varieties can bloom earlier.)
Flower Color: Blue, pink, purple, white (color depends on soil pH).
Plant Size: 3 to 6 feet tall.

Dried big-leaf hydrangea blooms create stunning indoor arrangements that make enduring long winters all the easier.

Conclusion

Colorful zinnia flowers growing in the spring or summer garden.

The best flowers to plant in May and June offer more than beautiful blooms. These resilient blossoms promise summer-long rewards with minimal fuss. Most attract legions of hungry bees, butterflies, hummingbirds, and other pollinators, making them superb additions to any garden!

What about you?

Will you plant some epic summer flowers in May or June this year?
Do you grow them to attract bees? Or for ornamental use?
Which summer flower cultivars will you grow first?

Thanks for reading.

Have a great day!