Most gardeners think the planting season is done in August until fall, but that's actually when some of the best opportunities begin. At this point, summer heat has probably been tough on spring plantings, leaving gaps in beds and containers that need filling. Fall bloomers are just waiting for their moment to shine.
The trick is knowing which flowers can handle late-summer planting and still deliver results before winter really sets in. I’ve chosen some that race from seed to bloom in just weeks for summer-fall transition color. Others need time to establish in a protected area away from the heat, but reward you with months of color that improves as temperatures cool.
Your success depends partly on where you garden and how much heat you're still dealing with. Here are some August flowers to plant, and when you can expect results.
Marigold
You can't go wrong with marigolds for quick August flower color. These heat-loving annuals go from seed to bloom in about just over a month, making them perfect for zones 3-10, where you've got time before frost hits. French marigolds mature even faster than African types if you're working with a short window.
Plant them now and they'll bloom steadily until hard frost kills them off. In warmer zones (8-10), that could mean flowers well into December. Northern gardeners in zones 3-5 might get a few weeks of blooms before frost arrives in October.
The secret to success is getting them established before peak heat hits, either by protecting them or planting nursery starts over seeds for quicker results. Water regularly until they're settled, then they'll handle drought and heat. Their pest-repelling properties make them valuable additions near vegetables that are still producing.
Zinnia
Fast-growing zinnias are ideal August flowers, especially in zones 4-9 where summer heat helps them establish quickly. These annuals can bloom within 60 days of planting, giving you plenty of time for fall color even in areas with early frost.
Zinnia blooms love the heat, but survive through temperature dips in early fall too. Plant now in moderate zones and expect blooms through November. Northern zones (4-5) will see flowers until first frost. In my zone 10 garden, the zinnias last well into fall, providing a great color transition until other fall blooms kick in.
Direct seeding works better than transplants for August flowers since zinnias hate root disturbance. Scatter seeds in prepared soil and keep moist until germination. Once established, they'll handle dry spells better than most other annuals.
Sunflower
Quick-maturing sunflower varieties work well for August planting in zones 5-9, though you'll want to choose types that bloom quickly rather than the giant varieties that need a full season. Branching types give you more flowers over a longer period than single-stem giants. ‘Elves Blend’ is a mix of dwarf types that works well and provides some variety.
In zones 7-9, August-planted sunflowers can bloom well into November before frost stops them. Northern gardeners should focus on the fastest varieties to ensure blooms before early frost arrives.
Plant them where they'll get full sun and room to spread. Even dwarf varieties need space for their extensive root systems. Alternatively, plant in containers so you can move pots around to take advantage of the best positions. The late-season blooms provide valuable food for birds.
Pansies
Here's where timing gets tricky. Pansies are cool-weather lovers that struggle in August heat but flower prolifically once temperatures drop. August planting works if you can keep them cool and moist during establishment, preferably in a protected area with enough sun for germination.
These tough annuals handle frost like champions, blooming through fall and often into winter. Zones 6 and below get reliable blooms from September through frost, sometimes surviving under snow to bloom again in spring.
Start with nursery plants rather than seeds for August planting if you can’t give them the right conditions to sow from seed. The heat stress of germination is too much for most pansy seeds. Keep new transplants shaded and consistently moist until cooler weather arrives in September.
Celosia
Heat-loving celosia is a great August flower in zones 4-10, racing to bloom in just two months. The feathery plume types and cockscomb varieties both handle late-season planting well, providing unique textures that complement traditional fall flowers.
These annuals bloom until hard frost kills them, which means December flowers in zones 8-10 and October blooms in northern areas. The flower heads dry beautifully on the plant, extending their decorative value even after peak bloom.
Plant in full sun and don't worry about babying them. They'll perform better with some neglect than with constant attention.
Aster
In cooler areas (zones 4-6), August planting gives perennial asters time to establish before their natural fall bloom period. Warmer zones can still plant these August flowers, but may need shade protection initially.
These perennials bloom from September through November in most areas, with some varieties continuing until hard frost. The flowers provide crucial late-season nectar for butterflies and other beneficial insects, making them great additions to fall vegetable gardens.
Annual asters work better for immediate color. Perennial types planted now will give you bigger, better displays next year while still providing some fall color this season.
Bachelor's Buttons
Also called cornflowers, these cottage garden favorites handle August planting well in most zones. They're one of the fastest annuals, often blooming within 6 weeks of sowing. The blue flowers like ‘Blue Boy’ are classic, but there are varieties that offer pink, white, and burgundy flowers too.
Cool fall weather brings out their best performance. Plant these August flowers now for blooms from September until hard frost. They also make excellent cut flowers that last well in bouquets.
Direct sowing works better than transplants since bachelor's buttons develop deep taproots that don't like disturbance. Scatter seeds and barely cover them, as they need light to germinate properly.
California Poppy
These drought-tolerant annuals don’t mind hot weather and handle August planting in zones 6-10. They'll bloom within 8 weeks of sowing and continue until frost stops them. The papery flowers close on cloudy days but put on brilliant displays in sunshine.
California poppies can perform when planted in late summer rather than spring in many areas. Fall weather keeps them blooming longer since they tend to shut down during extreme summer heat. Expect flowers through November in warmer zones.
Rich, fertilized ground makes them grow too lush and bloom less, so plant them in a spot where other flowers struggle to grow due to poor soil conditions. Scatter seeds where you want them and leave them alone. They'll often self-seed for next year's display.
Penstemon
Perennial penstemons planted in August need protection from heat, but reward you with spectacular fall blooms and years of future performance. Zones 5-9 work best for August flower planting, though initial establishment requires careful attention to watering and cool soils.
These native perennials bloom from late summer through fall once established, with tubular flowers that hummingbirds find irresistible. Plant now for some fall color this year, and you'll have much better displays next season.
Keep new plantings consistently moist and provide afternoon shade during the hottest part of late summer. Once fall weather arrives, they'll settle in quickly and prepare for next year's growth.
Sweet Alyssum
Cool-weather sweet alyssum struggles with August heat but will thrive from September onwards. In zones 6-9, August planting is possible if you can keep plants cool and moist during the hottest weeks (like in containers). Northern gardeners will have better success since their August temperatures are already moderating.
This August flower blooms continuously from establishment until hard frost, carpeting areas with tiny white, pink, or purple flowers. In mild zones, August plantings often survive winter to bloom again in spring.
Start with nursery plants rather than seeds for August establishment. The germination stress is too much during hot weather, but established plants adapt quickly once cooler weather arrives.
Calendula
Another cool-weather lover that needs careful handling during August establishment but delivers outstanding fall performance. Zones 6-9 work best for late-summer planting, with cooler zones having better establishment success.
Calendula flowers improve dramatically in fall weather, with cooler temperatures producing larger, more colorful blooms that last longer. Plant now for flowers from September through hard frost, potentially November or December in warmer areas.
The edible flowers add color to salads and cooking, making calendula both ornamental and useful. Start with transplants rather than seeds to avoid germination issues in late-summer heat.
Petunia
Petunias can be great August flowers in zones 5-10, though they may sulk initially during establishment. They will bloom within two months and continue until frost kills them.
Since extreme summer heat often makes them look leggy, fall temperatures will improve flowering and overall appearance. August plantings give you fresh, vigorous plants that bloom beautifully through fall. Expect flowers until November in warmer zones.
Choose heat-tolerant varieties like Wave petunias for best results with late-season planting. Keep new transplants well-watered until they establish, then they'll handle some drought stress.
Snapdragon
Like other cool-season annuals on this list, snapdragons are tricky for August planting but worth the effort. These annuals need protection from late-summer heat. Northern zones won’t struggle, but those in warmer climates need to sow in a cooler, protected spot for germination success.
Tall varieties planted now can bloom from September through hard frost, providing vertical accents that many fall flowers lack. In mild climates, they can survive winter as short-lived perennials.
Start with nursery plants and provide afternoon shade during establishment. Once September brings cooler weather, they'll take off and bloom steadily through fall.