7 Fast-Growing Summer Flowers You Can Still Plant Now

Can You Really Plant Summer Flowers This Late?

In many parts of the United States, yes. Gardeners in areas with long summers may continue sowing annual flowers through midsummer, while northern gardeners need to focus on the quickest cultivars. Clemson Extension specifically recommends filling July gaps with warm-season annuals such as cosmos, cleome, marigolds, sunflowers, and zinnias for later color. University of Georgia Extension also identifies cleome, cosmos, marigold, and zinnia as quick-growing annual choices.

Use Your First-Frost Date as the Deadline

Count backward from your region’s average first frost. A variety listed at 50 days to bloom is a reasonable candidate when you have at least 60 frost-free days remaining. The extra time provides a buffer for slow germination, cloudy weather, transplant shock, or a squirrel conducting an unauthorized seed excavation.

Choose Early, Dwarf, or Compact Varieties

Do not assume the tallest flower is the fastest. Giant sunflowers and towering cosmos often need more time than compact selections. Look for seed packets labeled “early,” “dwarf,” “compact,” “bedding,” or “container.” These varieties generally spend less energy building skyscraper stems before producing flowers.

1. Zinnias

Typical time to bloom: About 50 to 70 days

Best conditions: Full sun and well-drained soil

Best uses: Cutting gardens, borders, raised beds, and containers

Zinnias are the emergency responders of the summer flower garden. They germinate readily in warm soil, grow quickly, and produce cheerful flowers in nearly every shade except true blue. Their upright stems also make excellent cut flowers, so one small seed packet can decorate both the yard and the kitchen table.

Sow seeds directly about one-quarter inch deep, following the packet’s spacing instructions. Keep the seedbed evenly moist until seedlings become established, but avoid repeatedly soaking the foliage once plants mature. Zinnias appreciate airflow, and crowding them can encourage powdery mildew. Water near the soil instead of spraying the leaves like you are pressure-washing a driveway.

For late planting, choose compact or early-flowering cultivars rather than giant exhibition types. Deadhead faded flowers or cut stems regularly to encourage more branching and new buds. Illinois Extension lists zinnias among annuals suitable for direct seeding and cut-flower gardens, while Clemson and Illinois sources identify them as tender annuals that thrive after soil and air temperatures have warmed.

2. French Marigolds

Typical time to bloom: About 45 to 60 days

Best conditions: Full sun and moderately fertile, well-drained soil

Best uses: Edging, vegetable gardens, window boxes, and containers

French marigolds are compact, colorful, and pleasantly difficult to discourage. They produce yellow, orange, rust, red, and bicolored flowers on tidy plants that usually fit easily along walkways or between vegetables.

Dwarf marigolds are particularly useful for late sowing because some can flower in approximately five to seven weeks. Sow the seeds shallowly, keep the soil moist during germination, and thin seedlings so air can circulate around the foliage. They tolerate ordinary garden soil, but full sun produces the strongest plants and most abundant flowering.

Remove spent blooms before they form seeds. Deadheading redirects the plant’s energy toward additional flowers and helps keep the display attractive. Penn State Extension notes that dwarf marigolds may develop flowers in about five weeks, while University of Illinois Chicago reports that marigolds commonly flower around 45 to 50 days after seeding. Missouri Botanical Garden describes French marigolds as compact annuals well suited to colorful garden displays.

3. Dwarf or Early Sunflowers

Typical time to bloom: About 50 to 75 days for early varieties

Best conditions: Full sun and well-drained soil

Best uses: Cutting gardens, pollinator beds, fences, and large containers

You do not need to grow a 12-foot sunflower that requires air-traffic clearance. Dwarf, pollen-producing, branching, and early cut-flower sunflowers can bloom much faster than giant seed-producing varieties.

Plant sunflower seeds about one inch deep in their final location. Sunflowers develop a taproot and generally prefer not to be shuffled around after germination. Protect the planting area from birds and rodents until seedlings appear. A lightweight mesh or temporary row cover can prevent your flower bed from becoming an all-you-can-eat seed buffet.

Read the variety description carefully. Some single-stem cutting sunflowers bloom quickly but produce only one main flower, while branching types provide multiple blooms over a longer period. University of Minnesota Extension reports that sunflower seeds commonly germinate within seven to ten days and recommends succession planting or combining varieties with different maturity dates for continuous flowering.

4. Cosmos

Typical time to bloom: About 60 to 75 days

Best conditions: Full sun and average or relatively lean soil

Best uses: Cottage gardens, pollinator beds, informal borders, and bouquets

Cosmos creates the illusion that you carefully designed a romantic meadow, even when your actual technique was scattering seeds and hoping for the best. Its fernlike foliage grows quickly, followed by airy daisy-shaped flowers in white, pink, red, orange, and yellow, depending on the species and variety.

Direct-sow cosmos seeds shallowly and keep the surface damp until germination. Once established, the plants are reasonably drought tolerant. Avoid heavy fertilizer, which can produce enormous green plants with embarrassingly few flowers. Rich soil sometimes turns cosmos into an enthusiastic foliage factory.

Taller varieties may need support in windy areas, while dwarf cultivars work well in containers and late-season beds. Pinching young plants once they develop several sets of leaves can encourage branching. Regular cutting and deadheading prolong flowering. Illinois Extension describes cosmos as an easy-care, full-sun annual that flowers through summer and into fall, while Oklahoma State Extension warns that overfertilizing and overwatering can reduce blooms.

5. Nasturtiums

Typical time to bloom: About 35 to 60 days

Best conditions: Full sun in cooler areas; afternoon shade in very hot climates

Best uses: Containers, raised beds, window boxes, slopes, and edible gardens

Nasturtiums offer round leaves, jewel-colored flowers, and an easygoing personality. Compact types form tidy mounds, while trailing varieties spill from containers or scramble across bed edges. The leaves and flowers are commonly grown as edible garnishes and have a peppery flavor, although gardeners should only eat plants positively identified and grown without unsuitable pesticides.

Soak the large seeds for several hours before planting if recommended on the packet, then sow them directly because nasturtiums do not enjoy root disturbance. Average or lean soil is ideal. Too much nitrogen encourages a magnificent crop of leaves accompanied by approximately three flowers hiding underneath.

Nasturtiums perform best where summers are not brutally hot. In the Deep South and desert regions, midsummer sowing may be less successful than planting toward the end of summer for fall flowers. North Carolina Extension recommends poor to average, well-drained soil and notes that afternoon shade can help during hot summers. It also cautions that excess fertilizer increases foliage while reducing flowering.

6. Moss Rose

Typical time to bloom: Roughly 6 to 8 weeks in warm conditions

Best conditions: Full sun, heat, and sharply drained soil

Best uses: Rock gardens, hot borders, hanging baskets, containers, and dry slopes

Moss rose, also known as Portulaca grandiflora, is the flower to plant when your garden seems determined to imitate a pizza oven. Its succulent foliage stores moisture, while its bright, silky blooms open most enthusiastically in strong sunshine.

Scatter the tiny seeds over prepared soil and press them gently into the surface. Do not bury them deeply. Maintain light moisture during germination, then reduce watering as the plants establish. Moss rose dislikes soggy soil far more than it dislikes neglect. Poor drainage may cause crown or root rot.

Because the plants remain low, use them near the front of beds or let them trail from pots. They are particularly useful in locations where thirstier annuals collapse dramatically every afternoon. North Carolina Extension identifies moss rose as highly tolerant of drought and heat and recommends full sun with sandy, rocky, or otherwise well-drained soil. Proven Winners likewise describes portulaca as a quick-growing warm-season flower suited to heat, humidity, drought, and relatively poor soils.

7. Cleome

Typical time to bloom: About 70 to 80 days after germination

Best conditions: Full sun and moist but well-drained soil

Best uses: Back borders, cottage gardens, pollinator gardens, and large beds

Cleome, commonly called spider flower, is the tallest choice on this list. Its dramatic flower clusters sit above strong stems and palm-shaped leaves, creating quick vertical interest where a bare fence or empty background needs rescuing.

Sow seeds after the soil has warmed, covering them with approximately one-quarter inch of soil. Clemson Extension recommends soil temperatures around 70 to 75 degrees Fahrenheit and reports that seedlings generally appear in seven to fourteen days. Depending on the cultivar, plants can begin blooming about 70 to 80 days after germination.

Cleome is best for gardeners with a reasonably long frost-free season. Compact cultivars mature sooner and are easier to fit into smaller landscapes than traditional five-foot plants. Once established, cleome handles heat well, attracts pollinators, and may continue blooming until frost. Illinois Extension lists a bloom season extending from summer into October.

How to Help Late-Planted Flowers Grow Faster

Prepare the Soil Before Opening the Seed Packet

Remove weeds, loosen the upper few inches of soil, and break apart large clods. Seeds make poor demolition equipment. A smooth, crumbly seedbed improves seed-to-soil contact and helps roots expand quickly.

Water Gently but Consistently

Freshly planted seeds need steady moisture near the soil surface. A forceful hose stream can wash tiny seeds into the next zip code, so use a watering wand, mist setting, or fine sprinkler. After seedlings develop deeper roots, water less frequently but more thoroughly.

Do Not Bury Seeds Too Deeply

Follow the seed packet’s planting depth. Tiny seeds usually need only a thin covering or firm contact with the soil surface. Large seeds, such as sunflowers and nasturtiums, can be planted deeper. Excessive depth delays emergence and may cause seeds to rot.

Thin Seedlings Promptly

A crowded row may look productive, but overcrowded plants compete for light, moisture, and nutrients. Thin seedlings according to the mature spacing on the packet. Proper spacing also improves airflow and reduces disease pressure. Illinois Extension notes that spacing plants more closely fills a bed faster, but each plant still needs enough room to reach a healthy mature size.

Deadhead for More Flowers

Remove faded blooms from zinnias, marigolds, cosmos, and similar annuals before they finish producing seed. This encourages many varieties to continue flowering. Illinois and Penn State Extension explain that deadheading keeps plants attractive and redirects energy away from seed production.

Practical Experience: What Usually Happens in a Late-Summer Planting

The following observations reflect common home-gardening experience rather than a guarantee for every climate, garden, or seed packet.

The first lesson is that warm soil changes everything. Seeds that seem stubborn in chilly spring ground often germinate much faster during summer. Zinnias and sunflowers may appear in less than a week when moisture and temperature are favorable. That speed is exciting, but it creates a new problem: the surface can dry out astonishingly fast. A bed watered before breakfast may look dusty by late afternoon. Checking moisture with a fingertip is more useful than following a rigid watering schedule.

The second lesson is that late planting rewards smaller ambitions. Gardeners often reach for the most dramatic seed packetthe eight-foot sunflower, the enormous cosmos, the cleome that appears capable of hiding a compact car. Yet compact cultivars frequently provide better results when frost is approaching. A two-foot sunflower covered in manageable blooms is more satisfying than a seven-foot plant that produces its first bud the night before a freeze.

Another common discovery is that thinning seedlings feels cruel but works. New gardeners may leave every seedling because each tiny plant seems heroic. Two weeks later, the bed resembles rush-hour traffic. Crowded seedlings stretch toward the light, dry out unevenly, and develop poor airflow. Removing weaker plants allows the remaining ones to branch, flower, and withstand temporary drought more effectively.

Mulch also requires restraint. A thin layer around established seedlings helps conserve moisture and suppress weeds, but burying newly planted seeds beneath several inches of wood chips creates an obstacle course. It is usually better to leave the seeded strip uncovered until plants emerge, then place mulch aroundnot on top ofthe seedlings.

Late-sown flowers can look unimpressive during their first few weeks. The garden may contain nothing but short green stems while mature plants elsewhere are already blooming. Then growth accelerates. Cosmos becomes feathery, zinnias begin branching, marigolds form rounded mounds, and sunflowers suddenly gain height almost daily. The transformation often feels more dramatic than a spring planting because warm weather keeps growth moving.

Containers provide a useful backup plan. Pots warm quickly, are easier to protect from animals, and can be moved to maximize sunlight. A container of dwarf marigolds, nasturtiums, or moss rose can produce color even when the main flower bed is full, compacted, or temporarily occupied by a suspiciously confident groundhog.

The final lesson is to enjoy the process rather than judging the planting only by how long it blooms. Even a late sunflower that flowers for two weeks can feed pollinators, brighten a corner, and provide seeds for birds. A modest patch of zinnias may supply several bouquets. The season does not need to last forever to be worthwhile. Gardening is full of temporary successes, which is a poetic way of saying frost eventually wins every argument.

Final Thoughts

It is not automatically too late to grow flowers simply because summer is underway. Fast-growing annuals can turn open soil into a colorful late-season display, especially when you choose early cultivars and still have enough frost-free days remaining.

For the quickest results, begin with French marigolds, compact zinnias, dwarf sunflowers, nasturtiums, or moss rose. Choose cosmos for airy height and abundant cutting flowers, or cleome when your growing season is long enough to support a taller background plant. Give the seeds sunlight, consistent moisture during germination, sensible spacing, and regular deadheading. Then step back and let summer do the heavy lifting.

Note: Planting dates, growth rates, and bloom times vary by cultivar and region. Check the seed packet, your average first-frost date, and guidance from your local Cooperative Extension office before planting.