Illinois gardeners know August is the time to plant flowers that will provide color through September and October. Choosing the best flowers to plant in August in Illinois means picking varieties that can handle late summer heat and still bloom into fall. This guide covers top picks, planting tips, and care advice for a vibrant late-season garden.
August in Illinois brings hot days and warm soil, which is perfect for getting certain flowers established. You want plants that mature quickly and thrive in the remaining growing season. Let’s look at the top choices that will keep your garden colorful.
Best Flowers To Plant In August In Illinois
When you think about the best flowers to plant in August in Illinois, focus on annuals and perennials that bloom fast and tolerate heat. Marigolds, zinnias, and sunflowers are excellent annuals. For perennials, consider coneflowers and black-eyed Susans. These flowers handle Illinois’s late summer conditions well.
Marigolds are a top pick. They grow quickly from seed or transplant and bloom within weeks. They love full sun and well-drained soil. Plant them in beds or containers for instant color.
Zinnias are another winner. They come in many colors and attract butterflies. They need full sun and regular watering. Deadhead spent blooms to encourage more flowers.
Sunflowers add height and drama. Choose dwarf varieties for smaller spaces. They grow fast and produce cheerful blooms that last into fall.
Annual Flowers For Late Summer Planting
Annuals complete their life cycle in one season, making them ideal for August planting. They bloom quickly and provide color until frost. Here are the best annuals for Illinois in August.
- Marigolds: Plant in full sun. Water at the base to prevent mildew.
- Zinnias: Sow seeds directly in soil. Thin seedlings to 6 inches apart.
- Cosmos: Tolerate poor soil. Bloom in 7-8 weeks.
- Nasturtiums: Edible flowers. Grow in partial shade.
- Celosia: Unique feathery blooms. Love heat.
These annuals thrive in warm soil. Water them deeply after planting. Mulch around the base to retain moisture and keep roots cool.
Perennial Flowers That Bloom In Fall
Perennials come back year after year. Planting them in August gives them time to establish roots before winter. Some perennials bloom in late summer and fall, providing color when other plants fade.
- Coneflowers: Purple or pink blooms. Attract pollinators.
- Black-Eyed Susans: Golden yellow petals. Drought tolerant once established.
- Sedum: Succulent leaves. Pink or red flowers in September.
- Asters: Blue, purple, or pink blooms. Great for fall bouquets.
- Chrysanthemums: Classic fall flower. Plant in full sun.
Water perennials regularly for the first few weeks. They need consistent moisture to develop strong roots. Apply a slow-release fertilizer at planting time.
Tips For Planting Perennials In August
Plant perennials in the morning or evening to avoid heat stress. Dig a hole twice as wide as the root ball. Mix compost into the soil. Water thoroughly after planting.
Mulch with 2-3 inches of organic material. This keeps soil cool and reduces watering needs. Check soil moisture daily during hot spells.
How To Prepare Your Garden For August Planting
Preparing your garden bed is key for success. August soil can be dry and compacted. Follow these steps to get your garden ready.
- Clear the area: Remove weeds, debris, and old plants.
- Loosen the soil: Use a garden fork or tiller to break up compacted soil.
- Amend the soil: Mix in 2-3 inches of compost or aged manure.
- Level the bed: Rake the soil smooth.
- Water deeply: Moisten the soil a day before planting.
Test your soil pH if possible. Most flowers prefer a pH between 6.0 and 7.0. Add lime to raise pH or sulfur to lower it if needed.
Watering Strategies For August Flowers
August heat means your flowers need more water. Water deeply and less frequently to encourage deep root growth. Aim for 1-2 inches of water per week.
Water early in the morning to reduce evaporation. Avoid wetting the foliage to prevent fungal diseases. Use soaker hoses or drip irrigation for efficiency.
Check soil moisture by sticking your finger 2 inches into the soil. If it feels dry, it’s time to water. Container plants may need daily watering.
Fertilizing Tips For Late Summer Blooms
Fertilizer gives your flowers a boost. Use a balanced, slow-release fertilizer at planting time. For annuals, apply a liquid fertilizer every 2-3 weeks.
Perennials benefit from a light application of compost tea or fish emulsion. Avoid high-nitrogen fertilizers, which promote leaves over blooms.
Stop fertilizing by mid-September to allow plants to harden off for winter. Over-fertilizing can lead to weak growth.
Top 10 Flowers To Plant In August In Illinois
Here is a list of the top 10 flowers that perform well in Illinois’s August conditions. Each one offers unique benefits and beauty.
- Marigolds: Easy to grow, pest resistant.
- Zinnias: Long blooming, great for cutting.
- Sunflowers: Tall and cheerful.
- Cosmos: Airy foliage, low maintenance.
- Nasturtiums: Edible and colorful.
- Celosia: Unique texture, heat loving.
- Coneflowers: Hardy perennial, attracts bees.
- Black-Eyed Susans: Native plant, drought tolerant.
- Sedum: Succulent, fall interest.
- Asters: Late season color.
These flowers are proven winners for Illinois gardens. They handle the heat and provide color until the first frost.
Native Flowers For Illinois Gardens
Native plants are adapted to Illinois’s climate and soil. They require less water and fertilizer. They also support local pollinators.
- Purple Coneflower: Native to prairies. Blooms from June to October.
- Butterfly Weed: Orange flowers. Attracts monarch butterflies.
- New England Aster: Purple blooms in fall. Grows 3-6 feet tall.
- Goldenrod: Yellow plumes. Blooms in late summer.
- Joe-Pye Weed: Tall plant with pink flowers. Prefers moist soil.
Plant natives in groups for the best visual impact. They naturalize over time and require minimal care.
Where To Buy Native Plants In Illinois
Look for native plants at local nurseries or garden centers. Many Illinois counties have native plant sales in spring and fall. Online retailers also offer native seeds and plants.
Check with your local extension office for recommendations. They often have lists of native plants for your area.
Common Mistakes When Planting Flowers In August
Avoid these common mistakes to ensure your flowers thrive. August planting requires extra attention to detail.
- Planting too deep: Bury the root ball at soil level. Deep planting can rot stems.
- Overwatering: Soggy soil leads to root rot. Water only when the top inch is dry.
- Skipping mulch: Mulch conserves moisture and regulates soil temperature.
- Ignoring spacing: Crowded plants compete for nutrients and air.
- Forgetting to deadhead: Remove spent blooms to encourage more flowers.
Also, avoid planting in the hottest part of the day. Early morning or late afternoon is best. Give plants time to adjust before the sun gets intense.
Dealing With Pests And Diseases
August heat can bring pests like aphids, spider mites, and Japanese beetles. Inspect your plants weekly. Use insecticidal soap for mild infestations.
Fungal diseases like powdery mildew are common in humid weather. Space plants for good air circulation. Water at the base to keep leaves dry.
Remove infected leaves promptly. Apply neem oil as a preventive measure. Healthy plants are less susceptible to problems.
Fall Care For August-Planted Flowers
As September and October arrive, adjust your care routine. Reduce watering as temperatures cool. Stop fertilizing by mid-September.
For annuals, enjoy them until the first frost. Then remove them from the garden to prevent disease. Compost healthy plants.
For perennials, cut back dead foliage after frost. Mulch around the base for winter protection. Water deeply before the ground freezes.
Extending The Bloom Season
You can extend the bloom season with a few tricks. Cover tender plants with row covers if a light frost is forecast. Water the soil before a frost to release heat.
Plant in containers that can be moved indoors or to a sheltered spot. Use cold frames to protect plants from early frosts.
Choose late-blooming varieties like chrysanthemums and asters. They naturally bloom into October and sometimes November.
Frequently Asked Questions
Can I plant flowers in August in Illinois?
Yes, August is a great time to plant flowers in Illinois. The warm soil helps roots establish quickly. Choose heat-tolerant varieties for best results.
What are the best annuals to plant in August in Illinois?
Marigolds, zinnias, cosmos, and sunflowers are excellent choices. They bloom fast and provide color through fall.
How often should I water flowers planted in August?
Water deeply 2-3 times per week, depending on rainfall. Check soil moisture regularly. Container plants may need daily watering.
Do perennials planted in August survive winter?
Yes, if planted early enough in August, perennials have time to establish roots. Mulch well and water before frost for best survival.
What flowers bloom in September in Illinois?
Chrysanthemums, asters, sedum, and goldenrod bloom in September. Coneflowers and black-eyed Susans often continue blooming too.
Final Thoughts On August Planting In Illinois
August planting in Illinois is rewarding. With the right flowers and care, you can enjoy a colorful garden through fall. Start with marigolds, zinnias, or coneflowers for reliable blooms.
Prepare your soil well, water consistently, and watch for pests. Your garden will thank you with vibrant colors. Happy planting!