The Best Heat-Tolerant Annual Flowers for Southern Gardens

In the South, it’s just too hot and humid for gardening much. We’re reduced to an hour or two of tolerable temperatures in the morning and maybe at dusk. But the good news is that we don’t have to forgo all gardening completely. There are many heat-tolerant annual flowers that thrive in the scorching sun, and many of them reach maturity pretty quickly.

Summer is when vegetable gardens in the South seem to perish in front of our very eyes. (If you’ve seen bacterial blight, then you know what I’m talking about.) Forget about summer tomatoes, much less lettuce. Our peppers will survive the summer, but don’t expect much in the way of a harvest.

So, it’s time to turn to sturdier, less fussy garden plants, and you may wonder what flowers tolerate full sun and heat?

Heat-Tolerant Annual Flowers You Can Plant Now

June 1st is when I turn my attention to ornamentals. I used to stick to perennial flowering bushes because of the low-care factor. June is a fine time to take cuttings, too.

However, once I discovered what annuals are heat tolerant and can thrive in our damp summers, I’ve found that annuals can flourish with summer neglect as well.

Best of all, most grow quickly and require little care. So, once they’ve germinated and put out true leaves, you won’t even need to stand in the blazing sun to water them.

Indian Blanket Flower, Gaillardia pulchella

heat tolerant indian blanket flower

Indian Blanket Flower is a quick-growing annual that just loves the heat. It’s native to the eastern and southeastern U.S., and while it’s drought-resistant, it can handle more moisture than its Western cousin, the Common Blanket Flower.

So, if you have hot, wet summers, like we do in Florida, Indian Blanket will add color to sunny areas in your garden. It will also tolerate partial shade. It reaches 1 to 2 feet high, with bright, cheerful yellow and red flowers.

It’s considered of special value to native bee populations as well. If you’re gardening for wildlife and don’t have room in your beds for flowers, it’s also one of the best heat tolerant annuals for containers.

Indian Blanket is one of the heat-tolerant annual flowers that are perennial in subtropical coastal regains. And in many areas, it will reseed prolifically.

Best of all, you’ll get flowers in only about 8 weeks!

You can purchase Indian Blanket Flower seeds here.
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Coreopsis, Coreopsis tinctoria

heat tolerant southern wildflowers

Sometimes called tickseed and plains Coreopsis, the Florida state wildflower produces masses of happy yellow and red flowers that bees simply adore. It puts up with a lot – even a hot Southern summer. You’ll find coreopsis available in other shades, as well, with deep red being the most common.  

If you have poor, sandy soil, coreopsis will love you and produce flowers in about 60 to 70 days. This Southern U.S. native wildflower requires no feeding but do like some moisture.

This wildflower ranges from 1 to 3 feet tall and flowers in about 80 to 90 days.

Purchase Coreopsis tinctoria seeds here, or Tall Red Coreopsis tinctoria seeds here.
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Salvias are often perennial in the South, which makes them a particularly good choice for summer color. When the temperatures start to rise, it’s nice to know that your future holds flowers, even if it’s too hot for gardening.

Scarlet Sage

Salvias come in a range of colors, but Scarlet Salvia is native to the southeast and provides food for hummingbirds and butterflies. Its natural range is coastal areas, from South Carolina, around Florida, and up the Gulf Coast to Texas. Best of all, it blooms nearly all year long in subtropical climates and self-seeds like a champ.

You can purchase Scarlet Sage seeds here.
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Blue Salvia

heat tolerant blue salvia

Even though it’s native to the Southwest, Blue Salvia (Salvia farinacea), or Blue Sage, also does well in the Southeast. Hummingbirds love it and in frost-free areas, it will bloom year-round.

Because it’s so drought-tolerant, it makes a fantastic water-wise flower to add to your landscaping or butterfly garden.

You can purchase Blue Salvia seeds here.
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zinnias are heat and sun tolerant for southern summer gardens

Zinnias are native to Mexico and Central America, and have become naturalized to the Southwest U.S. But they grow anywhere that offers heat and sunshine. They come in a wide range of colors and heights, and they’re easy to grow.

Zinnias are a no-brainer for summer color, particularly for beginning gardeners, lazy gardeners, and kids. These heat-tolerant annual flowers germinate in as little as three days in the right conditions, but no more than 7 to 10. Best of all, they flower in about 50 days, which means you can add them now and add beauty to your garden well before fall.

You can buy Zinnia seeds here.
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Celosia, Celosia

flame shaped celosia

Celosia looks like we feel on the beach in July – like we’ve burst into flames. In fact, the name is derived from the Greek word for “burning.” It’s a dramatic addition to any garden because of the vivid colors and unique flame shape.

It likes some moisture but loves full sun. You’ll find it in a range of bright, jewel-toned colors.

There are a variety of flower shapes, however, including Celosia cristata, which is also called cockscomb. Celosia spicata resembles wheat.

They offer plenty of nectar for bees and butterflies, but also make excellent dried flowers.

Buy Celosia seeds here.
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Cosmos, Cosmos bipinnatus

heat tolerant cosmos flowers

Cosmos looks so delicate, but it’s tough as nails in the summer garden. This Mexican native plant loves the heat and will thrive under the sun.

Cosmos feature frothy, fernlike leaves reaching from 2 to 4 feet tall. They have small, dainty blossoms in a wide range of colors. Most are in the pink and white shades, but you’ll also find them in rich maroons and deep lavender.

They’ll grow anytime the weather is warm and bloom in only two months. So, it’s not too late to grow a cottage-garden style annual flower, even in June.

You can purchase cosmos seeds here.
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And a dwarf variety here that only reaches about 1 foot tall.
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French Marigolds

French marigold

These sunny, yellow flowers just seem built for hot summer gardens. French marigolds are usually just called “marigolds” in the U.S., but it distinguishes them from Calendula, which are commonly called “marigolds” in the UK and EU.

French marigolds are members of the Tagetes genus and native to Mexico and Central America.

French marigolds are long-lived annuals with a wide range of colors, heights, and growth habits. Some reach as tall as 3 feet, while other works as a compact ground cover. Because of their compact growth, they’re one of the best heat tolerant annuals for containers.

As well as being easy to grow, they’re also easy to propagate. You can take cuttings at nearly any time during the active season, so if you can preserve your favorite bloom color indefinitely.

They grow quickly and mature in about 45 to 50 days, tolerating heat and drought once established.

You can purchase French Marigolds here.
Buy seeds

Mexican Sunflower, Tithonia rotundafolia

Mexican sunflower, Tithonia bloom

If you like height and drama during the hot summer days, consider adding Tithonia to your flower garden. It isn’t a fast-growing annual, like others on this list, but in areas of the country with mild or late winters, it will bloom beautifully throughout the fall until the first frost of winter

Tithonia delivers heights up to 6 feet tall and can grow up to 3 feet wide. It features soft, spade-shaped foliage and vivid orange flowers with red centers.

It prefers poor, well-draining soil and can be sown directly or into large cells for transplanting.

Purchase Mexican Sunflower seeds here.
Buy seeds

Heat Tolerant Annual Flowers Add Sunshine During the Rainy Season

Depending on where you live in the South, summer can really be the gloomiest time of the year. Much of the Gulf Coast and Atlantic Coast enjoy a rainy season, with regular storm watches. Some years, it seems that most of the color is in the cocktails we concoct for Hurricane Parties.

But I’m here to tell you that it doesn’t have to be that way.

Sure, your spring tomatoes are all dead. The squash has been quashed by pests. The latest storm blew over your pole beans.

Even the bananas, who should be able to stand up to all this, seem sad and beaten.

It’s not too late to add a little color to your Southern garden with some fast-growing annuals.

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