12 Fast-Growing Annuals To Quickly Fill Your Garden With Color

Black-Eyed Susan

The Black-Eyed Susan has mustard-colored, red, or orange flowers with petals facing downward and a brown puffy center that entices pollinators to the garden. "Black-Eyed Susans are known for their rapid growth, prolific flowering, and ability to establish themselves in garden beds and borders quickly," says Root. "Rudbeckia hirta, commonly known as Black-eyed Susan, is a biennial or short-lived perennial but often grown as an annual." 

Ziegler adds that there are different sizes and hues to choose from, such as Prairie Sun and Goldilocks. These bloom in late summer and early fall offering nectar and pollen later in the season for pollinators.

• Botanical Name: Rudbeckia hirta
• Sun Exposure: Full, partial
• Soil Type: Well-drained and moist. Loamy, clay, sandy
• Soil pH: 5.5-6.8
  

Larkspur

A cool-season annual, you'll have pretty flowers before many of the other fast-growing annuals begin to bloom. "Larkspur is another favorite because it offers true-blue flowers or pink or purple and it adds a delicate look to the garden," says Justin Hancock, a horticulturist for Costa Farms, one of the largest horticultural growers in the world, headquartered in Florida. They're easy to grow, making it simple to have gorgeous, colorful flowers in the garden. "Sprinkle some seeds in a sunny or partly shaded spot with moist, well-draining soil, and in no time, you’ll be rewarded with gorgeous blooms," he says. 

• Botanical Name: Consolida
• Sun Exposure: Full or partial
• Soil Type: Well-draining
• Soil pH: 6.5-7.0
  

Lemon Basil

Herbs add fragrance and flowers to the garden. Lemon basil is one of Ziegler's favorites to grow. "We grow Mrs. Burn’s Lemon Basil that has a delightful lemon scent, which takes a bouquet of flowers over the top," she says. Not only does it smell delicious, but when in bloom, this herb attracts bees and butterflies. "If left in the garden, pollinators particularly love it and if planted on the edge of a walkway it is always nice to rub up against it to release the fragrance," she says. 

• Botanical Name: Ocimum basilicum citriodorum
• Sun Exposure: Full
• Soil Type: Well-draining
• Soil pH: 6.0-7.0

Marigolds

Vibrant, pom-pom style flowers, typically in orange and yellow hues, marigolds stand out in any garden. They are fast to grow, known for deterring pests, and as a bonus, you can eat them. If you haven't planted this fast-growing annual, what are you waiting for? "Marigolds are known for their rapid growth from seed to mature plant and ability to produce abundant flowers relatively quickly," says Root. "Their bright and colorful blooms make them popular choices for adding beauty to garden beds, borders, and containers, especially for gardeners looking for quick results."

• Botanical Name: Tagetes
• Sun Exposure: Full
• Soil Type: Well-drained
• Soil pH: 6.0-7.0

Lime Light Millet Grass

An ornamental grass that's easy to grow, Lime Light Millet produces beautiful seed heads that add vibrancy and greenery to any bouquet. "We love planting Lime Light Millet grass because it’s beautiful and it is also fast!," says Ziegler. "It’s really useful as a cut flower but if left in the garden it matures into big seed heads that the songbirds love."

• Botanical Name: Setaria italica
• Sun Exposure: Full
• Soil Type: Well-draining
• Soil pH: 5.5-7.0

Moonflower Vines

An easy-to-grow annual, Moonflowers are vining plants that produce flowers that only open at night, hence their name. "These climbing vines boast large white flowers that bloom at night, creating a truly unique spectacle," says Root. "It’s very cool to stroll through the garden in the evening and have these captivating blooms greet you." She likes to plant moonflowers near doors and walkways so they are easily visible at night.

• Botanical Name: Ipomoea alba
• Sun Exposure: Full
• Soil Type: Well-draining
• Soil pH: 6.0-7.5

Nigella

Nigella, also referred to as Love in a Mist, produces beautiful flowers within two to three months after planting. "It shows off gorgeous blue, purple, or white flowers that appear in profusion above lacy leaves and it adds incredible texture to the garden," says Hancock.  "As a bonus, after the flowers fade, the balloon-like seed pods provide further interest." They typically self-seed so despite being an annual, you'll likely find it crop up on its own year after year. 

• Botanical Name: Nigella damascena
• Sun Exposure: Partial to Full 
• Soil Type: Well-draining
• Soil pH: 6.0-7.0

Snow on the Mountain

If you live in an area with many deer or rabbits that consider your garden a buffet line, you'll want to plant Snow on the Mountain. "Being a Euphorbia, it’s deer- and rabbit-resistant, which is super helpful in a lot of gardens," says Hancock. This fast-growing annual is native to North America and produces variegated foliage.  

• Botanical Name: Euphorbia marginata
• Sun Exposure: Full
• Soil Type: Well-draining, sandy
• Soil pH: 6.8-7.2

Snapdragon

Snapdragon flowers look like a dragon's snout and when the petals are carefully pinched, the mouth seems to open and close. "The flowers come in a wide range of colors, so they make it easy to get the look you want, and they’re fabulous spring-into-summer colors or even all summer long, depending on your climate," says Hancock. 

Snapdragons add lots of texture and dimension to a garden. "You can choose from tall, upright varieties that add height and vertical appeal to the garden or shorter, bushier varieties," he adds.

• Botanical Name: Antirrhinum majus
• Sun Exposure: Partial to Full
• Soil Type: Well-draining
• Soil pH: 6.2-7.0

Sunflowers

There's nothing quite like the sunflower to say summer is here. "Super fun to grow because they sprout and grow up fast and they are so showy," says Root. Some types take a couple of months to bloom, while others can take three to four months. Choose varieties that grow quickly. "The quickest sunflower varieties are single-stemmed—one stem and flower per plant," says Ziegler. "Be sure to select sunflower varieties like Vincent and ProCuts that have a short 50-60 day seed to bloom timing," says Ziegler.  

Her tip for having constant sunflowers all summer long and to have them as cut flowers is to plant sunflowers each week from spring till first frost. Another benefit of growing this annual every year in the garden is it attracts birds and pollinators.

• Botanical Name: Helianthus annuus
• Sun Exposure: Full Sun
• Soil Type: Dry to Medium, Well-draining, Average Fertility
• Soil pH: Acidic to Neutral (5.5-7.8)

Wishbone Flower

Wishbone flowers, also called Torenia, are trumpet-shaped in white, yellow, pink and purple tones. "Torenia is a lesser-known flower that is great to grow with its long-lasting, non-fading blooms," says Root. They prefer partial shade and moist soil yet can tolerate growing in full sun. "Its versatility, compact growth habit, and low maintenance requirements make it an excellent choice for those looking to add unique charm to their garden," she adds. 

• Botanical Name: Torenia fournieri
• Sun Exposure: Partial shade to Full
• Soil Type: Well-draining
• Soil pH: 5.6-7.0

Zinnias

Zinnias can flower within two months of sowing seeds. "Zinnias are always at the top of the growth list and a fairly quick bloomer," says Ziegler. With vibrant blooms, Zinnas liven up any garden and attract pollinators. "They are neglect-proof and very low maintenance," says Root.

Ziegler likes to speed up the process by sowing seeds early so they're ready to transplant right after the last frost. "We have 3-week-old transplants ready to be planted in the garden just as soon as our expected last frost date passes and this puts us weeks ahead."

• Botanical Name: Zinnia elegans
• Sun Exposure: Full
• Soil Type: Well-draining
• Soil pH: 5.5-7.5