Gardening Plants & Flowers Flowers

15 Best Annual Flowers for the Cool Season

lobelia

The Spruce / Autumn Wood

Cool weather can be hard to garden in because you never know how long it will last. But there are many garden flowers that prefer the cool days of spring and fall. Often, gardeners think only of perennials for a sequence of bloom. Many cool-season annuals look wonderful in containers and growing these flowers will make your gardening season seem that much longer. If you live in a warm climate, some of these flowers will be perennial for you and will bloom from fall through spring.

Extend your gardening season by adding one of these 15 cool-season annual flowering plants to your garden.

What Are Hardy Annuals?

Hardy annuals are often referred to as "cool flowers" due to their tolerance of cold temperatures and ability to withstand light frost. Many can be planted out before the last frost or can survive through first frost in autumn. In warmer growing zones some hardy annuals continue to bloom through winter. Hardy annuals often reseed easily but most die back during the heat of summer and rebloom in autumn.

When to Plant Hardy Annuals

With a few exceptions most hardy annuals can be direct sown in the garden or transplanted out prior to final frost. Planting is traditionally done in spring although many can be planted out in autumn in warmer zones for winter blooming.

Protecting Hardy Annuals From Extreme Cold

Although hardy annuals survive frost, a hard freeze can lead to plant loss. If a freeze is forecast after you set out your plants or if extended periods of extremely cold weather threaten, plants may require some protection.

  • Bring potted plants indoors
  • Cover plants or seed beds with blankets
  • Put down a thick layer of mulch around plants or over seed beds
  • 01 of 15

    Bachelor's Buttons, Cornflower (Centaurea cyanus)

    Bachelor Buttons

    The Spruce / Marie iannotti

    You won't often find bachelor's buttons at most nurseries but you can find seeds. These dainty, colorful blooms grow easily when directly sown in the garden and will reseed freely. A cottage garden plant, bachelor's buttons give their best display in cool seasons, so if you started some in the spring, watch as they perk up again in the fall.

    • USDA Zones: 2 to 11
    • Color Varieties: Blue, purple, pink, and white
    • Sun Exposure: Partial to full sun
    • Soil Needs: Well-draining, alkaline soil
  • 02 of 15

    Calendula, Pot Marigold (Calendula officinalis)

    Pot marigold with small orange flowers in sunlight

    The Spruce / Evgeniya Vlasova

    Calendula, or pot marigolds, look like fall flowers, with their rich golden and rust colors, and they do best later in the season. They might even withstand a light frost if they're established. Many calendulas will self-seed and treat you to a spring bloom as well. Calendula is a popular ingredient in herbal skin care products and also is used as a natural dye. The flower is edible and is often interplanted with tomatoes to deter insect pests. Calendula is a good choice for the herb and vegetable garden.

    • USDA Zones: 9 to 11
    • Color Varieties: Bright yellow to deep orange, creams, and pinks
    • Sun Exposure: Full sun to partial shade
    • Soil Needs: Average, well-drained soil rich in organic material
  • 03 of 15

    Diascia

    Diascia plant with pink flowers on wavy stems

    The Spruce / Evgeniya Vlasova

    Diascia, though relatively new in gardens, has quickly become popular. Often called by the common name "Twinspur", this plant is a relative of the snapdragon and blooms in the spring and fall. The tiny, profuse trailing blossoms make it perfect for containers. Diascia is generally grown from cuttings, which can make it an expensive annual to purchase. You may be able to overwinter yours indoors or take your own cuttings. Diascia is perennial, with a good winter, in USDA Zone 9 or higher.

    • USDA Zones: 9 to 11
    • Color Varieties: Pink, white, coral, orange, red, and plum
    • Sun Exposure: Partial to full sun
    • Soil Needs: Fertile, well-drained soil
  • 04 of 15

    Annual Larkspur (Consolida ajacis)

    Annual larkspur with deep blue star-shaped flowers closeup

    The Spruce / Evgeniya Vlasova

    Where summers are too extreme to grow delphiniums, larkspur makes an eminently acceptable substitute. Deadhead this early spring bloomer throughout the summer then give it a little extra food and it may revive to put on a fall show. These make excellent cut flowers.

    • USDA Zones: 2 to 10
    • Color Varieties: Purple, pink, white, and blue
    • Sun Exposure: Full sun to partial shade
    • Soil Needs: Slightly moist to dry, well-drained soil
    Continue to 5 of 15 below
  • 05 of 15

    Lobelia (Campanulaceae)

    Lobelia plant with small purple-blue flowers near rocky soil

    The Spruce / Evgeniya Vlasova

    Lobelia will shut down during the summer, but given cool temperatures, it will bloom with profusion. If you planted yours in the spring, once the flowers start to slow down, cut it back by half and allow it to regrow and rebloom.

    • USDA Zones: 10 to 11
    • Color Varieties: White, blue, purple, lilac-pink, and cherry-red
    • Sun Exposure: Full sun to partial shade
    • Soil Needs: Evenly moist and well-drained soil
  • 06 of 15

    Nasturtium (Tropaeolum spp.)

    Nasturtium plant with rounded leaves surrounding bright red flower

    The Spruce / Evgeniya Vlasova

    Nasturtiums will bloom throughout summer and well into fall. They are rejuvenated by the cooler air. Even their crisp fall colors advertise that they belong in the fall garden. Nasturtiums don't transplant well and you may be better off direct seeding. Keep them well watered in the heat of summer. They have large seed pods that are easy to collect and save to replant next season.

    • USDA Zones: 2 to 11
    • Color Varieties: Red, orange, pink, yellow, and cream
    • Sun Exposure: Full sun
    • Soil Needs: Evenly moist and well-drained soil
  • 07 of 15

    Nierembergia 'Mont Blanc'

    nierembergia rivularis, september
    Sunniva Harte / Getty Images

    The Nierembergia 'Mont Blanc' variety rescued nierembergia from obsolescence. Nierembergia is hardy to USDA Zone 10 and can even be overwintered indoors, but you might not bother because it is fairly easy to grow from seed. 'Mont Blanc' won the All America Selection award, but the blue-flowered varieties are rising in popularity.

    • USDA Zones: 7 to 10
    • Color Varieties: Blue, purple, and white
    • Sun Exposure: Full sun to partial shade
    • Soil Needs: Sandy, silt, loamy soil
  • 08 of 15

    Petunia (Petunia x hybrida)

    Petunia plant with magenta flowers in hanging pot

    The Spruce / Evgeniya Vlasova

    Gardeners think of petunias as a bedding mainstay, and the flowers actually bloom best in cool temperatures. The Wave series has become especially popular and if you don't like deadheading, Wave petunias are for you. The tiny calibrachoa petunia makes a nice textural accent in containers.

    • USDA Zones: 8 to 11
    • Color Varieties: Various, including pink, purple, and yellow
    • Sun Exposure: Full sun
    • Soil Needs: Well-draining, clay, or sandy soil
    Continue to 9 of 15 below
  • 09 of 15

    Snapdragon (Antirrhinum majus)

    Snapdragon plant with pink flowers clustered on thin stems

    The Spruce / Evgeniya Vlasova

    Snapdragons offer color and a bit of height, depending on the variety. There are also new trailing snapdragons that work wonderfully in containers. Look for the Luminaire series. Snapdragons are hardy at least to USDA Zone 8. With some protection, they may also survive in Zone 7.

    • USDA Zones: 7 to 10
    • Color Varieties: White, yellow, pink, red, orange, peach, purple, and violet
    • Sun Exposure: Full sun to partial shade
    • Soil Needs: Well-draining, rich, moist soil
  • 10 of 15

    Viola, Pansy (Violaceae)

    Pansy plant with purple-blue and yellow rounded flowers

    The Spruce / Evgeniya Vlasova

    You may still have some pansies from last spring languishing in your garden beds. Look around and see if they are perking up for fall. Violas and pansies will bloom for weeks. Deadheading will keep them setting new buds. Look for some of the newer varieties that can handle a slight freeze.

    • USDA Zones: 3 to 8
    • Color Varieties: Light to deep violet, white, blue, yellow, cream, and multi-colors
    • Sun Exposure: Full sun
    • Soil Needs: Well-draining, rich, moist soil
  • 11 of 15

    Dianthus (Dianthus chinensis)

    Dianthus

    Westend61 / Getty Images

    Also known as annual pinks, these fragrant flowers bloom from spring through to first frost in a wide range of colors. Single to double disc-like blooms grow in compact carpet-like mounds. Annual dianthus serves as an excellent bedding plant in cool, sunny areas and containers.

    • USDA Zones: 3 to 10
    • Color Varieties: Pink, purple, red, white, yellow
    • Sun Exposure: Full to part sun
    • Soil Needs: Well draining, neutral to alkaline, sandy loam
  • 12 of 15

    Sweet Pea (Lathyrus odoratus)

    Sweet Pea

    Flavia Morlachetti / Getty Images

    A long time staple of the classic cottage garden, sweet pea is a flowering vine that prefers cool temperatures. Bloom periods last from 6 to 8 weeks and depend on climate. In areas with cool summers, sweet peas bloom in late spring or autumn. Warmer climates see flowers in winter and spring. Vines grow to 8 feet and require trellising. Plants die back naturally in hot weather.

    • USDA Zones: 3 to 8
    • Color Varieties: Red, pink, blue, white, lavender
    • Sun Exposure: Full sun
    • Soil Needs: Well draining, alkaline
    Continue to 13 of 15 below
  • 13 of 15

    Love-in-a-Mist, Nigella (Nigella damascena)

    Love-in-a-Mist

    Thomas Winz / Getty Images

    Ferny foliage gives this reseeding annual its common name of Love-in-a-Mist and makes this traditional cottage garden flower a standout among broad leaved plants. Nigella blooms for short periods of about three weeks from spring through autumn and winter in warmer growing zones. Succession plant for continuous bloom until flowers begin to reseed on their own.

    • USDA Zones: 2 to 11
    • Color Varieties: Blue, purple, pink, white
    • Sun Exposure: Full to part sun
    • Soil Needs: Well draining, neutral
  • 14 of 15

    Hardy Mums (Chrysanthemum morifolium)

    Hardy Mum

    Cappi Thompson / Getty Images

    Hardy mums are primarily grown as annual autumn bloomers in northern climates and as perennials in the south. Plants start to set buds as nights become longer and bloom for as long as eight weeks in autumn. Transplant potted mums into the garden in late October once flowers are spent.

    Cut foliage back to about 3 inches and add mulch for winter protection. These mums are generally hardy to 20°F. but survival is dependent on climate and conditions. Increase your chances of overwintering success by selecting a cultivar best suited to your environment.

    • USDA Zones: 4 to 9
    • Color Varieties: Yellow, red, pink, purple, orange, white
    • Sun Exposure: Full sun
    • Soil Needs: Moist, neutral, well draining
  • 15 of 15

    Alyssum (Lobularia maritima)

    Alyssum

    Catherine McQueen / Getty Images

    Alyssum blooms in spring and autumn forming a carpet of small colorful flowers. This is a cool season plant set out after danger of frost that dies back in the heat of summer to rebloom again once temperatures begin to drop in autumn. In frost-free zones alyssum is grown throughout winter. The plant emits a sweet honey like fragrance and is popular as a filler in flower beds, potted plants, and hanging baskets.

    • USDA Zones: 5 to 9
    • Color Varieties: White, pink, purple
    • Sun Exposure: Full to part sun
    • Soil Needs: Neutral, moist, well draining