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5 Annual Flowers that Can Take the Heat

Summers have been hitting record marks in a lot of the U.S., which isn’t good news for some flowers. When temperatures reach the 90s day after day, and the rain shuts off to go along with it, some flowers stop flowering – or fry around the leaf edges and wilt to the ground in the worst cases.

On the other hand, some annual flowers don’t mind the heat and bloom even during triple-digit spells. These are ones that earn “FlameProof” honors from the Dallas Arboretum, which each year runs annual-flower trials in its long, hot, humid summers. (If a flower is FlameProof in Dallas, it should have no problem handling summers anywhere in the U.S.!)

Here are five of the best that can stand the heat:

Zinnia

The dwarf types are best at holding off mildew as well as tolerating heat.  Most are hot colors (orange, red, gold), but a few come in pink or white. These grow 15-18 inches tall and do best in full sun.

Glennimage / iStock / Getty Images Plus

Glennimage / iStock / Getty Images Plus

Vinca

These foot-tall annuals with the glossy leaves can take the worst heat and drought you can throw at an annual. They come in nickel- to quarter-sized flowers of white, pink, rose, red, lavender, and pale blue and do best in full sun.

Xtrekx / iStock / Getty Images Plus

Xtrekx / iStock / Getty Images Plus

Salvia

Both the blue-blooming and red/purple types thrive in heat. The spiky, butterfly-attracting flowers grow on 12- to 15-inch stems. Give them full sun to light shade

Suprabhat Dutta / iStock / Getty Images Plus

Suprabhat Dutta / iStock / Getty Images Plus

Lantana

An arching, perennial sub-shrub in the South, lantana grows as a trailing annual in cooler climates. It’ll bloom all summer and even survive a frost or two. Figure on 15-18 inches tall with a 2- to 3-foot spread. Lantana blooms red, gold, orange, lavender, and in several bicolors, ideally in full sun.

Anukoon Supawong / iStock / Getty Images Plus

Anukoon Supawong / iStock / Getty Images Plus

Angelonia

These spiky 15- to 18-inch annuals with the orchid-like flowers might look dainty, but they’re surprisingly heat- and drought-tough. They bloom in purple, pink, blue-purple, and white. Give them full sun to light shade.

George Weigel

George Weigel

Heat-beating tips for annual flowers

  1. Improve the soil. Loosen it a foot deep and mix in generous amounts of compost to encourage roots to quickly spread out.
  2. Keep plants well watered. After the plants are established by June, deeper waterings every two or three days help roots go down deeper than shallow daily sprinklings. Never let the soil go so dry, though, that the plants wilt.
  3. Maintain one to two inches of organic mulch around the plants. This slows moisture loss and insulates the soil from the sun’s rays. Don’t let the mulch touch the plant stems.
  4. Keep weeds away from your plants (they take important nutrients from your wanted plants) and feed them at the same time with Preen Garden Weed Preventer Plus Plant Food.

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