Oklahoma’s late summer heat demands flowers that are tough enough to withstand triple-digit temperatures. If you’re searching for the best flowers to plant in August in Oklahoma, you need varieties that laugh at humidity and thrive in our clay soil. August planting can feel like a gamble, but with the right picks, your garden will stay colorful well into fall.
August in Oklahoma is brutal. The sun beats down, rain is spotty, and your garden might look tired. But don’t give up on color yet. Many flowers actually prefer being planted in late summer. They settle in during the heat and bloom beautifully when cooler weather arrives. Let’s look at the top choices that will survive and thrive.
Best Flowers To Plant In August In Oklahoma
When we talk about the best flowers to plant in August in Oklahoma, we mean plants that can handle heat, drought, and our unpredictable storms. These flowers are tough, low-maintenance, and will reward you with blooms from late summer through the first frost. Here are the top contenders.
Marigolds
Marigolds are practically bulletproof. They love heat, bloom nonstop, and repel pests. In Oklahoma’s August sun, marigolds actually perform better than in spring. Plant them from seed or transplants. They germinate fast in warm soil.
- Plant in full sun
- Water deeply once a week
- Deadhead spent blooms for more flowers
- Choose French or African varieties
Marigolds come in yellow, orange, and red. They look great in borders, containers, or mixed beds. Plus, they’re cheap and easy to find at any garden center.
Zinnias
Zinnias are another heat-loving champion. They come in every color except blue. Zinnias grow quickly from seed and bloom within 6-8 weeks. In August, direct sow them in well-drained soil. They’ll flower until frost.
- Scatter seeds on loosened soil
- Cover lightly with 1/4 inch of soil
- Water gently every day until sprouts appear
- Thin seedlings to 6-12 inches apart
Zinnias attract butterflies and bees. They make excellent cut flowers too. Just keep an eye out for powdery mildew in humid weather. Space them well for air flow.
Cosmos
Cosmos are tall, airy flowers that sway in the wind. They thrive in poor soil and full sun. August is perfect for planting cosmos in Oklahoma. They handle the heat without complaint. Cosmos bloom in pink, white, and deep burgundy.
These flowers are drought-tolerant once established. Water them sparingly. Too much water makes them leggy. Plant cosmos along fences or at the back of borders. They can reach 3-5 feet tall.
Sunflowers
Sunflowers are iconic for Oklahoma summers. They love the heat and grow fast. Plant sunflower seeds directly in the ground in August. Choose varieties that mature in 60-70 days. Dwarf types work well for small spaces.
- Plant seeds 1 inch deep
- Space 6-12 inches apart for smaller types
- Water deeply but infrequently
- Stake tall varieties if needed
Sunflowers attract birds and pollinators. They also provide shade for smaller plants. Harvest seeds for snacks or leave them for wildlife.
Portulaca (Moss Rose)
Portulaca is a succulent-like flower that thrives on neglect. It loves heat, poor soil, and little water. In August, plant portulaca from transplants. They spread quickly and form a colorful ground cover.
Portulaca blooms in neon shades of pink, orange, yellow, and red. The flowers open in full sun and close at night. They’re perfect for hanging baskets, rock gardens, or hot spots where other plants fail.
Lantana
Lantana is a shrubby perennial that blooms from spring until frost. In Oklahoma, it’s often grown as an annual. August is a great time to plant lantana. It handles heat, humidity, and drought like a champ.
Lantana comes in yellow, orange, pink, and purple. It attracts butterflies and hummingbirds. Plant it in full sun with well-drained soil. Lantana is deer-resistant too. Just be aware that all parts are toxic if eaten.
Celosia
Celosia has unique, flame-like blooms in bright colors. It loves heat and grows well in Oklahoma’s August weather. Plant celosia from transplants for quicker results. They bloom continuously until frost.
Celosia needs full sun and moderate water. The flowers last a long time in the garden and as cut flowers. They come in red, orange, yellow, and pink. Use them as focal points in beds or containers.
Gomphrena (Globe Amaranth)
Gomphrena is a tough, heat-loving annual. It produces round, clover-like flowers in purple, pink, white, and red. August planting works well because gomphrena thrives in hot weather. It’s also drought-tolerant.
These flowers are excellent for drying. They hold their color for months. Plant gomphrena in full sun with average soil. Space them 12 inches apart. They reach 1-2 feet tall and look great in borders.
Salvia
Salvia is a versatile flower that comes in many varieties. Most salvias love heat and bloom from summer to fall. August is a good time to plant salvia in Oklahoma. Choose varieties like ‘Victoria Blue’ or ‘Hot Lips’.
Salvia attracts bees, butterflies, and hummingbirds. It’s deer-resistant and low-maintenance. Plant in full sun with well-drained soil. Water regularly until established, then reduce watering. Salvia adds vertical interest to any garden.
Verbena
Verbena is a trailing or upright flower that thrives in heat. It blooms in clusters of small flowers in purple, pink, red, and white. August planting works well for verbena. It spreads quickly and fills in gaps.
Verbena needs full sun and moderate water. It’s perfect for hanging baskets, window boxes, or ground cover. Deadhead spent blooms to encourage more flowers. Verbena is also a favorite of butterflies.
Tips For Planting Flowers In August In Oklahoma
Planting in August requires some extra care. The heat can stress new plants. Follow these tips to give your flowers the best start.
Water Correctly
Water deeply in the morning. This gives plants moisture before the heat of the day. Avoid overhead watering in the evening. Wet leaves overnight can cause fungal diseases. Use soaker hoses or drip irrigation for best results.
New transplants need water every day for the first week. After that, water every 2-3 days. Established plants need deep watering once a week. Check soil moisture by sticking your finger an inch into the soil.
Mulch Well
Mulch is essential in August. It keeps soil cool, retains moisture, and suppresses weeds. Apply 2-3 inches of organic mulch around your plants. Use shredded bark, straw, or grass clippings.
Keep mulch away from plant stems to prevent rot. Replenish mulch as needed during the season. Mulch also adds nutrients as it decomposes.
Choose The Right Time To Plant
Plant in the evening or on a cloudy day. This reduces transplant shock. If you must plant during the day, provide temporary shade. Use shade cloth or an umbrella for a few days.
Water transplants immediately after planting. Add a weak fertilizer solution to help them settle. Avoid fertilizing during the hottest part of the day.
Prepare The Soil
Oklahoma soil is often heavy clay. Amend it with compost or aged manure before planting. This improves drainage and adds nutrients. Work the amendments into the top 6-8 inches of soil.
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. Well-prepared soil makes a huge difference.
Use Containers For Flexibility
Containers heat up fast in August. But they also let you control soil and water. Use large pots with drainage holes. Fill with high-quality potting mix. Place containers where they get morning sun and afternoon shade.
Container plants need more frequent watering. Check them daily. Add water-retaining crystals to the soil if you forget to water. Containers are great for patios, decks, and balconies.
Flowers To Avoid Planting In August In Oklahoma
Not all flowers can handle August planting. Avoid these until cooler weather arrives.
- Pansies and violas (they prefer cool weather)
- Snapdragons (they bolt in heat)
- Dianthus (struggles in high humidity)
- Sweet peas (need cool soil)
- Larkspur (germinates best in cool conditions)
Wait until September or October for these flowers. They’ll perform much better when temperatures drop.
How To Care For August-Planted Flowers Through Fall
Your August-planted flowers need care as summer turns to fall. Here’s how to keep them blooming.
Deadhead Regularly
Remove spent flowers to encourage more blooms. This tells the plant to keep producing flowers instead of seeds. Deadhead at least once a week. Use clean scissors or pinch with your fingers.
Some flowers like zinnias and marigolds respond well to deadheading. Others like cosmos may self-seed if you leave some flowers. Balance deadheading with letting some go to seed for next year.
Fertilize Lightly
Continue fertilizing every 2-4 weeks through September. Use a balanced, water-soluble fertilizer. Stop fertilizing in October to let plants slow down for winter. Over-fertilizing late can cause tender growth that frost kills.
For flowers like portulaca and lantana, less fertilizer is better. They bloom best in lean soil. Too much nitrogen makes them leafy with few flowers.
Watch For Pests
August heat brings pests like aphids, spider mites, and whiteflies. Check plants weekly. Spray with a strong stream of water to dislodge pests. Use insecticidal soap if needed.
Avoid broad-spectrum pesticides. They kill beneficial insects too. Encourage ladybugs and lacewings by planting dill, fennel, and yarrow nearby.
Prepare For Frost
First frost in Oklahoma usually arrives in October or November. Watch the forecast. Cover tender flowers with frost cloth on cold nights. Move container plants indoors or to a sheltered spot.
Some flowers like marigolds and zinnias will die with frost. Others like lantana may survive if mulched heavily. Enjoy your flowers while they last. Plan to replace frost-killed plants with cool-season annuals.
Frequently Asked Questions
Can I plant flower seeds in August in Oklahoma?
Yes, many flower seeds germinate well in August. Zinnias, marigolds, cosmos, and sunflowers are great choices. Keep seeds moist until they sprout. Provide shade for tender seedlings if the sun is intense.
What flowers bloom all summer in Oklahoma?
Lantana, portulaca, zinnias, and marigolds bloom from planting until frost. They thrive in heat and keep producing flowers with minimal care. Deadheading helps extend their bloom time.
Is it too late to plant flowers in August in Oklahoma?
No, August is not too late. Many flowers prefer warm soil for germination. You’ll get blooms from late summer through fall. Just choose heat-tolerant varieties and water carefully.
What perennials can I plant in August in Oklahoma?
Perennials like salvia, coneflower, black-eyed Susan, and daylilies can be planted in August. They need regular water until established. They’ll come back next year bigger and better.
How often should I water new flowers in August?
Water new flowers daily for the first week. Then reduce to every 2-3 days for the next two weeks. After that, water deeply once a week. Adjust based on rainfall and soil type.
Final Thoughts On August Planting In Oklahoma
August planting in Oklahoma is totally doable. You just need the right flowers and a little extra care. The best flowers to plant in August in Oklahoma are tough, heat-loving varieties that bloom until frost. Marigolds, zinnias, cosmos, sunflowers, portulaca, lantana, celosia, gomphrena, salvia, and verbena are all excellent choices.
Prepare your soil, water wisely, and mulch well. Deadhead regularly and watch for pests. With these tips, your garden will stay colorful through the hottest days and into fall. Don’t let the August heat scare you away from planting. Your flowers will thank you with vibrant blooms.
Remember, gardening in Oklahoma is about working with the climate, not against it. Choose flowers that love heat, and you’ll have a beautiful garden with less work. Happy planting