As summer begins to wind down, August offers the perfect opportunity to refresh your garden. By planting late-season annuals, you’ll enjoy vibrant colors and lush blooms well into the fall.
Whether you’re looking to fill empty spots in your flower beds, spruce up borders, or add charm to containers, these 15 annuals are sure to thrive in the warm days of August and reward you with consistent beauty until the first frost.
From Seed or Seedling?
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This late in the season, you’re definitely better off purchasing seedlings or starter plants from a nursery, as they will already be established and have a head start on growth. However, if you do decide to plant from seeds, make sure to follow the instructions on the packet carefully for best results.
Iowa State University Extension shares that direct seeding in August is hit-or-miss depending on days to maturity, local first-frost dates, and heat/drought; many extensions caution that warm, dry soil hinders germination and that you must “work backwards” from your frost date to ensure enough time.
Why Did We Choose 15 Plants?
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There are many different factors to consider when deciding how many plants to include in your garden. And Penn State emphasizes that these flowers can add some fall color to your garden.
We chose 15 as a good starting point for beginners because it allows for a diverse selection of plants without becoming too overwhelming or time-consuming. Although you can pick just one or all fifteen, depending on your garden and growing goals this season.
1. Marigold
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Marigolds bloom quickly and bring a cheerful burst of color to any garden. They’re heat-tolerant and easy to care for, making them a reliable choice for August planting. Available in shades of yellow, orange, red, and gold, marigolds are perfect for borders, beds, or containers.
Care Tips: Choose a sunny location with well-drained soil. Deadhead spent blooms regularly to encourage continuous flowering. Water deeply once or twice a week, especially during dry spells.
2. Zinnia
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Known for their vibrant colors and long-lasting blooms, zinnias thrive in the heat of late summer. These flowers attract butterflies and come in a wide array of hues, from bold reds and oranges to delicate pinks and whites.
Care Tips: Plant in full sun with fertile, well-drained soil. Deadhead spent blooms to promote additional flowering. Avoid overhead watering to prevent powdery mildew on leaves.
3. Wax Begonia
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Wax begonias feature waxy, heart-shaped leaves and clusters of small, long-lasting flowers. While technically perennials in tropical climates, they’re grown as annuals elsewhere and thrive in both sun and partial shade.
Care Tips: Plant in soil that retains moisture but drains well. Water regularly, especially during hot, dry periods, but avoid overwatering. Fertilize with a balanced, water-soluble fertilizer every few weeks to encourage continuous blooms.
4. Impatiens
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One of the few annuals that thrive in full shade, impatiens burst to life with colorful blooms from August until the first frost. They’re ideal for shady corners, under trees, or in containers on covered patios.
Care Tips: Plant in rich, well-drained soil with consistent moisture. Avoid letting the soil dry out completely. While they don’t require deadheading, you can pinch back stems for a bushier appearance.
5. Cosmos
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Cosmos are beloved for their delicate, feathery foliage and plentiful, daisy-like flowers that bloom in shades of pink, orange, white, and purple. These fast-growing flowers are perfect for filling space in borders or adding height to garden beds.
Care Tips: Plant in well-drained soil under full sun. Water sparingly; cosmos thrive in drier conditions. Deadhead regularly to extend the blooming period.
6. Petunia
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Petunias are versatile, sprawling flowers that work wonderfully in hanging baskets, containers, or garden borders. Modern varieties bloom profusely without the need for frequent deadheading, offering months of color.
Care Tips: Plant in fertile, well-drained soil with plenty of sunlight. Water weekly or more often during hot weather. Avoid overhead watering to keep foliage and blooms clean and healthy.
7. Globe Amaranth
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This heat-loving plant features globe-shaped blooms in bright shades of pink, purple, red, and orange. Globe amaranth is drought-tolerant and long-lasting, and its blooms can even be dried for autumn decorations.
Care Tips: Plant in well-drained soil and full sun. While drought-tolerant, consistent watering will encourage more prolific blooming. Deadhead occasionally to keep the plant tidy.
8. Celosia
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With feathery plumes or bold, cockscomb-shaped flower heads, celosia makes a striking addition to late-summer gardens. This fast-growing annual retains its vivid colors even as the blooms age.
Care Tips: Provide full sun and well-drained soil. Water when the top inch of soil feels dry. Fertilize every two to four weeks with a balanced liquid fertilizer to support ongoing growth.
9. Geranium
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Geraniums are versatile, dependable annuals that add a touch of elegance to containers, window boxes, or garden beds. Their clusters of blossoms come in a variety of shades, including red, pink, salmon, and white.
Care Tips: Plant in fertile, well-drained soil under full sun or light shade. Deadhead blooms regularly to promote new growth. Water deeply but allow the soil to dry out slightly between waterings.
10. Nasturtium
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Nasturtiums are a charming addition to any garden, offering brightly colored blossoms and edible leaves with a peppery flavor. These fast-growing plants bloom just a few weeks after sowing seeds and thrive in poor soil conditions.
Care Tips: Choose a sunny location with well-drained soil. Avoid overfertilizing, as too much nitrogen will encourage leaf growth at the expense of flowers. Water consistently but sparingly.
11. Angelonia
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Often called summer snapdragon, Angelonia produces clusters of orchid-like flowers in shades of white, pink, and purple. This heat-tolerant beauty adds vertical interest to gardens and containers.
Care Tips: Plant in full sun with moist, well-draining soil. Water deeply once or twice a week. Fertilize monthly with a balanced fertilizer to encourage abundant flowering.
12. Calendula
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Known for its bright orange and yellow blooms, calendula is a cold-hardy annual that thrives in cooler late-summer nights. Its cheerful flowers also attract pollinators like bees and butterflies.
Care Tips: Plant in rich, well-drained soil under full to partial sun. Deadhead faded blooms to support extended flowering. Water moderately, keeping the soil consistently moist.
13. Dianthus
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With its spicy-scented blooms in shades of pink, red, and white, dianthus is a great choice for August planting. Compact and low-maintenance, it works beautifully in borders or containers.
Care Tips: Plant in well-drained soil with full sun exposure. Water consistently to keep the blooms thriving. Pinch stems after flowering to encourage additional growth.
14. Sweet Alyssum
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Sweet Alyssum produces masses of tiny, honey-scented flowers that cascade over edges or spread gently across beds. Its delicate blossoms flourish in cooler late-summer conditions.
Care Tips: Choose a sunny location with slightly moist, well-drained soil. Water consistently during dry spells. To encourage continuous blooming, trim back stems mid-season.
15. Spider Flower (Cleome)
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Spider flowers stand out with their tall stems and unique, spiky blooms in shades of pink, purple, and white. They add vertical dimension to garden beds and attract pollinators.
Care Tips: Provide full sun and fertile, well-drained soil. Water regularly until established, then taper off slightly. Deadhead flowers to extend the blooming season.
Take Advantage of the Last Bit of Heat
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Don’t worry if summer feels like it’s slipping away—planting these 15 stunning annuals in August can reinvigorate your garden and keep it bursting with color until the first frost. By following these tailored care tips, you’ll ensure a seamless transition from summer vibrancy to fall charm. Head to your local nursery, grab some seedlings, and watch your garden transform in the late-season glow!
