What Seeds to Start in August: Your Complete Planting Guide
August might feel like the tail end of the gardening season — but for smart gardeners, it's actually one of the most strategic planting months of the year. There's a surprising number of seeds you can start in August for fall blooms, cool-season harvests, and even a head start on next spring. This guide breaks it all down by plant type and zone so you can make the most of every remaining week of the growing season.
Also see: Late Summer Color: Annual Flowers to Keep Your Garden Blooming Through Fall
Why August Is a Great Time to Start Seeds
Here's the gardening secret most people miss: August soil is warm, days are still long, and fall is coming — which means cool-season crops that struggled in summer heat will thrive in the weeks ahead. At the same time, warm-season flowers started now will bloom right through fall in warmer zones. And for gardeners in Zones 9–11, August is actually the beginning of the best planting season of the year.
The key is knowing what to plant when — and that's exactly what this guide covers.
Flowers to Start from Seed in August
Zinnias — Zones 7–11: Direct Sow Now for Fall Color
Zinnias are one of the best flowers to direct sow in August in warm climates. They germinate fast (5–7 days), grow quickly, and will bloom in 6–8 weeks — right as summer heat begins to ease. In Zones 7–11, an August zinnia planting gives you a spectacular fall flush of color before frost.
Zinnia Peppermint — A stunning bicolor zinnia with cherry-red and white striped petals. Fast-growing and prolific — perfect for an August direct sow in warm zones. Excellent as a cut flower too.
Zinnia Preciosa Pink — A beautiful soft pink zinnia with excellent heat tolerance. Direct sow in August for blooms from September through frost. A reliable performer in late-season gardens.
Salvia — Zones 8–11: Direct Sow or Transplant for Fall Blooms
Annual salvias are heat-lovers that thrive in late summer conditions. In Zones 8–11, direct sowing or transplanting salvia in August gives you strong fall color that lasts until frost. In cooler zones, start indoors now for transplanting in early September.
Salvia Victoria Blue — The classic border salvia with deep cobalt-blue spikes. Heat-tolerant and prolific — an excellent August planting for fall color in warm zones. Attracts hummingbirds and butterflies through the season.
Salvia Reddy Mix — A vibrant blend of red, purple, salmon, and white salvias. Fast-maturing and heat-tolerant — start in August for a colorful fall display in Zones 7–11.
Marigolds — Zones 7–11: Last Call for Fall Blooms
August is the last realistic window to direct sow marigolds for fall blooms in most zones. They germinate in 5–7 days and bloom in 6–8 weeks — giving you color right through October and November in warm climates.
Marigold Proud Mari Gold — A bold, golden-yellow marigold with large, fully double blooms. Direct sow in August for a spectacular fall display. Also excellent for pest control in vegetable gardens.
Pansies — All Zones: Start Indoors Now for Fall & Winter Color
August is the ideal time to start pansy seeds indoors for fall and winter color. Pansies need 10–12 weeks from seed to transplant size — starting in August puts them ready for outdoor planting in October and November, just as temperatures cool into their sweet spot.
Top Wave Pink Shades Pansy — A spreading, trailing pansy perfect for fall containers, hanging baskets, and window boxes. Start indoors in August for October transplanting. Blooms through winter in Zones 7–11.
Top Wave Marina Pansy — A beautiful blue-violet trailing pansy with excellent cold tolerance. Start indoors in August for fall and winter container displays. One of the most popular trailing pansy varieties we carry.
Also see: The Best Flowers to Start from Seed: Easy Blooms for Every Garden
Lisianthus — Zones 9–11: Start Now for Winter/Spring Blooms
In Zones 9–11, August is actually the perfect time to start lisianthus seeds indoors. With 5–6 months to bloom, seeds started in August will produce stunning flowers in January through March — peak season for lisianthus in warm climates.
Lisianthus Solo Violet — One of our most popular lisianthus varieties. Start pelleted seeds indoors in August in Zones 9–11 for spectacular winter blooms. Excellent as a cut flower and in containers.
Cut Flower Mix — Zones 8–11: Direct Sow for Fall Cutting Garden
Tall Annual Cut Flower Mix — A beautiful blend of tall cut flower annuals. Direct sow in August in Zones 8–11 for a fall cutting garden that produces through October and November. A great way to fill the garden with color and stems for arranging.
Also see: Cut Flower Seeds We Like To Grow
August Seed Starting by USDA Zone
| Zone | What to Start in August | Notes |
|---|---|---|
| Zones 3–4 | Pansies indoors; perennial seeds for overwintering | Frost arrives Sept–Oct; focus on cool-season starts |
| Zones 5–6 | Pansies indoors; spinach/lettuce direct sow; marigolds (early Aug only) | Last frost Oct; act fast on warm-season crops |
| Zones 7–8 | Zinnias, marigolds, salvia direct sow; pansies indoors; cool-season veggies | Excellent window for fall color and cool crops |
| Zones 9–10 | Zinnias, salvia, marigolds direct sow; lisianthus indoors; pansies indoors | August starts the best planting season of the year |
| Zone 11 | Most flowers and cool-season veggies; lisianthus indoors | Year-round growing; August begins peak season |
Shop Our August Planting Picks
|
Zinnia Peppermint Shop Now |
Zinnia Preciosa Pink Shop Now |
Salvia Victoria Blue Shop Now |
|
Salvia Reddy Mix Shop Now |
Marigold Proud Mari Gold Shop Now |
Top Wave Pink Shades Pansy Shop Now |
|
Top Wave Marina Pansy Shop Now |
Lisianthus Solo Violet Shop Now |
Tall Annual Cut Flower Mix Shop Now |
Need bulk quantities? Visit our sister site: Trailing Petunia Bulk Seeds for larger pack options.
Tips for August Seed Starting Success
- Work fast on warm-season crops. Every week in August that passes is a week less of growing time before frost. If you're in Zones 5–7, prioritize getting zinnias and marigolds in the ground in the first two weeks of August.
- Direct sow in the evening or on cloudy days. August heat can dry out newly sown seeds quickly. Water immediately after sowing and keep the soil consistently moist until germination.
- Start cool-season crops indoors. Pansies and lisianthus started indoors in August will be ready for outdoor planting when temperatures cool in fall — exactly when they perform best.
- Mulch direct-sown beds. A thin layer of straw or shredded leaves over newly sown seeds helps retain moisture and moderate soil temperature during August heat.
- Label everything. August plantings can be easy to forget about as the season winds down. Label rows and containers clearly so you know what's coming up.
Also see: Top Mistakes to Avoid When Planting Flower Seeds
Frequently Asked Questions: What Seeds to Start in August
What flower seeds can I plant in August?
In Zones 7–11, you can direct sow zinnias, marigolds, and salvia in August for fall blooms. In all zones, August is the ideal time to start pansies indoors for fall and winter color. In Zones 9–11, lisianthus started indoors in August will bloom in winter and early spring.
Is it too late to plant seeds in August?
Not at all — it depends on your zone and what you're planting. In Zones 7–11, August is an excellent time to direct sow fast-maturing flowers like zinnias and marigolds. In all zones, it's the perfect time to start cool-season flowers like pansies indoors. In Zones 9–11, August actually marks the beginning of the best planting season of the year.
What seeds germinate fastest in August?
Zinnias and marigolds are the fastest germinators in August — both sprout in 5–7 days in warm August soil. Salvia germinates in 10–14 days. Pansies started indoors germinate in 10–21 days at 65–70°F.
Can I start lisianthus seeds in August?
Yes — in Zones 9–11, August is actually the ideal time to start lisianthus seeds indoors. With 5–6 months to bloom, seeds started in August will produce flowers in January through March — peak lisianthus season in warm climates. See our full guide: Growing Lisianthus From Seeds.
What cool-season vegetables can I start in August?
August is a great time to direct sow spinach, lettuce, kale, arugula, radishes, and carrots in Zones 5–10. These crops prefer the cooler temperatures of fall and will germinate readily in warm August soil, then grow through the cooling weeks ahead. Start broccoli and cauliflower indoors in early August for transplanting in September.
Should I water more when starting seeds in August?
Yes — August heat dries out soil quickly. Check newly sown seeds daily and water gently to keep the top inch of soil consistently moist until germination. Once seedlings are established, water deeply but less frequently to encourage deep root growth. Mulching over direct-sown beds helps retain moisture significantly.
What's the best way to start seeds indoors in August?
Use a fine seed-starting mix, maintain consistent moisture, and provide 14–16 hours of light under grow lights or in a bright south-facing window. For pansies, keep soil temperature at 65–70°F — cooler than most summer seed starting. For lisianthus, maintain 72–76°F with a heat mat and high humidity during germination.
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