01 of 14
The Best Annual Flowers for Full Sun
If you have a sunny spot in your yard that looks perfect for a flower garden, make sure you choose plants that can thrive in hot sun, without a lot of extra care. This can be a bit tricky, if you want to grow annual flowers in full sun. It gets pretty hot sitting in full sun all day. Some plants love it, some faint. Humidity can add to the oppressiveness of hot days, but even dry heat can be uncomfortable, when the temperatures top 90 F. People have air conditioning to escape to, but our plants... have to learn to adapt.
Perennials with deep tap roots and water conserving leaves handle the heat of full sun well enough. But annuals never have a chance to develop an extensive root system and they already expend a lot of energy growing rapidly and flowering profusely.
You have to choose wisely, to find annual flowers that can stand up to extreme hot weather. With dry heat, a little afternoon shade and a good layer of mulch will help sustain many plants, but you don't want to be faced with constant watering. And in areas with high humidity, there are a host of additional problems waiting to pounce, especially if the heat and humidity persist through the night. These stressed plants are sitting ducks for insect pests and fungal diseases.
The following 12 plants can stand up to heat and humidity. You will want to get them established, before the worst of the heat sets in, and you will still need to keep them watered regularly. But they won't faint during the day or require a lot of additional care.
I've listed them as annuals, but as with most plants considered annuals, they are actually tender perennials. They cannot survive freezing temperatures and are grown as annuals in many climates. I've listed the USDA hardiness zones, in case you live in a warmer area.Continue to 2 of 14 below.
02 of 14
There are many varieties of amaranth. Some are grown strictly as flowers, some for their leaves and others for use as a grain. Amaranth is the most widely grown grain in the world. However gardeners love them for their chenille like blooms or colorful foliage.
Love-lies-bleeding (Amaranthus caudatus), with its long, dangling, mauve-pink flowers, and Joseph's Coat (Amaranthus tricolor), with splashy red and yellow leaves, are two you may be familiar with. Amaranth plants can grow from a few... inches to 8 ft. tall. They all grow well from seed and can handle just about any growing conditions, even indoors, as houseplants.
As with many of the plants on this list, amaranth is actually a perennial in USDA Hardiness Zones 10 - 11. However the ornamental varieties are often grown as annuals.Continue to 3 of 14 below.
03 of 14
For Bold Color in Hot, Dry Gardens, Look to Celosia
If you notice a similarity between the flowers of Celosia and amaranth, it's because they are both in the same family. The name Celosia comes from the Greek word for burned, because the flower heads of Celosia argentea (Syn. C. plumosa) look like flames. The colors are certainly brilliant. However there are other species of Celosia that are popular in gardens.
Celosia crestada, also called crested celosia or cockscomb, has rippled flower heads that look like a rooster's cockcomb. Celosia... spicata has much more subtle spiky flowers that are likened to spikes of wheat. And there are new hybrids being introduced all the time. The flowers remain attractive for weeks and most varieties also make great cut and dried flowers. They almost dry themselves
As you might expect from looking at them, these are semi-tropical perennials in USDA Hardiness Zones 9 - 12. However they are often grown as annuals.Continue to 4 of 14 below.
04 of 14
Spider Flowers Add Intrigue to the Garden
Cleome's common name is Spider Flower, for the long "legs" that jut out from the blooms. The plants start flowering from the bottom up, extending the bloom period for weeks. As the flowers fade, long, slender seed pods form. Cleome are prodigious self-seeders, but because most are hybrids, you never know what colors you will get next year, but most won't disappoint you.
If you live in USDA Hardiness Zones 8 - 11, your cleome could be short-lived perennials, but anyone can grow them as annuals.Continue to 5 of 14 below.
05 of 14
Cosmos Flowers Bloom Long and Seed Themselves
Cosmos flowers (Cosmos bipinnatus) are about as easy to grow as it gets. You can find them in rich, bright shades of pink, purple, orange and red, soft pastels, and even white. The flowers are only about 1 in. across, but they just keep coming. The plants are sturdy and intermingle well with other flowers. This is another eager self-seeder, but not to the point of nuisance.
Different varieties will grow from 1 - 4 ft. tall. Cosmos are easy to start from seed. Direct sow them anytime after your... last frost.
Cosmos are heat lovers that are perennial in USDA Hardiness Zones 9 - 11, but they are most often grown as annuals. Since they often self sow year after year, you may think they're perennial, even in your non-tropical garden.Continue to 6 of 14 below.
06 of 14
Nierembergia Plants are Ideal in Containers
These delicate, charming flowers are in the nightshade family. The difficult to spell name, Nierumbergia, is for the Spanish Jesuit and mystic Juan Eusebio Nieremberg. It's a mouthful, yet for some reason Nierumbergia remains more popular than its common name, Cupflower. Maybe that's because there are multiple plants with the common name of cupflower and it gets too confusing.
Nieremburgia is extremely popular in containers, but it's perfectly at home in the garden and makes a nice edging... plants. It has a clumping growth habit and quickly fills out.
Continue to 7 of 14 below.
07 of 14
Need a Quick, Colorful Climber? Try Cypress Vine
Tubular, star-shaped, red flowers and thin, ferny leaves makes Cypress vine (Ipomoea quamoclit) a very ornamental climber. It's in the same family as Morning Glory and grows just about as quickly, reaching 10 - 15 ft. in no time. It doesn't take as long as morning glories, to start blooming, but it will grow tall before it starts setting buds, so prepare to be patient. You can start them indoors, in peat or paper pots, a few weeks before your last frost date. But you can also direct seed... outdoors after danger of frost.
Be sure to give them something to climb or sprawl over. They will grab hold of other plants, but if you are using a trellis, you will need to help them get started, twisting around it.
Cypress vines are hardy perennials in USDA Hardiness Zones 8 - 11 and even gardeners in Zone 7 could have them over-winter in mild seasons, but they grow quickly enough for everyone to be able to grow them as annuals.Continue to 8 of 14 below.
08 of 14
Lantana Plants Offer Multiple Color Choices
If you're lucky enough to live in a climate where lantana (Lantana camara) is hardy, you probably have it growing as a shrub. It also trains easily into a standard or small tree. Many gardeners in colder climates do this and over-winter the plants indoors.
Lantana flowers are often bi- or tri-colored in wonderful sherbet shades. As with all the plants listed here, they bloom throughout the summer. All parts of this plant are poisonous and can cause skin irritation, so handle with care.
In USDA... Hardiness Zones 8 - 11, lantana can be grown as a perennial and can get quite large. However you will often find seedlings available in the annuals section.
Continue to 9 of 14 below.
09 of 14
Stop Taking Marigolds for Granted
They're so ubiquitous we don't give marigolds their due. These are extremely tough little work horses. They do best in full sun and when grown a little on the dry side. If crowded in damp conditions, they can be prone to mildew, but you can avoid that if you give them plenty of air flow. Deadheading will get them blooming repeatedly, but even if you don't bother with it, they will resume blooming soon enough.
Another under-rated feature of marigold is their use as companion plants, repelling... pests like asparagus beetles, bean beetles, nematodes and even rabbits.
Marigolds are perennial in the warm climates of USDA Hardiness Zones 9 - 11. Everyone else can grown them as annuals.Continue to 10 of 14 below.
10 of 14
Chile Peppers are As Ornamental as They are Hot
Okay, these are not technically grown for their flowers, but they're just as beautiful. Ornamental peppers are edible chile peppers and most are extremely hot. They are also generally small and difficult to harvest, but someone noticed how beautiful they are and thought to put them in the flower garden. You will need to keep an eye on them, while they are young and tender. Rabbits have been know to chew the stems. However once the stems begin to harden off, they are pretty much safe.
Just like... the peppers we grow in the vegetable garden, ornamental types go through several different colors, as they ripen. Some, like this tri-colored variety, have multiple colors on the plant at any given time.
Peppers are tropical perennials and are hardy in USDA Hardiness Zones 9 - 12, but they are frequently grown as annuals.Continue to 11 of 14 below.
11 of 14
Tall, Cheerful, Mexican Sunflowers
This might not be what you'd expect to see, if you planted sunflowers, but Tithonia, or Mexican sunflower, is definitely a sun lover. Give it a hot, sunny site and it could easily reach heights of 5 - 8 ft. tall. It is definitely a back of the boarder plant and may need some support or staking, especially in windy sites.
Tithonia is perennial in USDA Hardiness Zones 8 - 10, but the majority of gardeners grow them as annuals. Luckily they grow and bloom quickly.Continue to 12 of 14 below.
12 of 14
Verbena Plants Offer Plenty of Variety
There are several species of verbena that make great garden plants. Most start blooming early in the season and continue on until frost. There are low growing , ground covering verbenas, tall, airy Verbena bonariensis and upright Verbena rigida, which grows about 3 ft. tall.
Verbena can be prone to problems like botrytis, if it is grown in damp conditions. Although it needs moist soil to become established, once it has settled in, drier conditions will keep it happy.
USDA Hardiness Zones will vary... with variety, but they tend to be short-lived as perennials, grown as annuals.
Continue to 13 of 14 below.
13 of 14
Zinnias Come Alive in Hot Weather
Finally, a true annual. Zinnias (Zinnia spp. and hybrids) are native to Mexico and Central America. They truly love heat and bloom so easily, you can use them as a cut flower and they will simply bloom again, in a day or two.
Older varieties are prone to powdery mildew, in damp or humid weather. It doesn't stop them from flowering, but it does make the foliage look unattractive. Some of the newer series, like Profusion and Zahara, don't have that problem. Their flowers tend to be a bit... smaller, but just as abundant. And there's a zinnia color for everyone, from peppermint stripes, to eye-popping golds to delicate neutrals.
Continue to 14 of 14 below.
14 of 14
Want More Flower Choices?
If you liked these plants, there are plenty more annuals to grow in your garden.
- Easiest Annuals to Start from Seed
- Annuals that Seed Themselves
- Easiest Annuals to Direct Sow
- Tall Annual Flowers for Impact
- 3 Tips to Keep Your Annual Flowers Blooming
- Attracting Butterflies to Your Garden