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Summer Flowers that Can Take the Heat

By: Karen Weir-Jimerson
Is your garden suffering from the heat in the dog days of summer? Here are some tender perennials that don’t mind high temps this time of year. Put them on your must-grow list!

Beat the summer heat

When summer temperatures soar, plants may stop blooming, wilt, drop leaves and flowers, lose color or launch into seed production. Learn how you can help prevent heat from taking its toll on your garden, and meet 6 flowers that can take the heat.

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summer-flowers-that-can-handle-the-heat-Add-mulch: Mulch is one way to hold moisture and cool the soil when temperatures soar. Light-colored mulches like this shredded cedar reflect heat best.

Cooling solutions for hot days

When the temperatures soar, help your plants weather the heat.

Add mulch

The old saying about keeping a cool head in hot situations is just the opposite for plants, who would rather have cool roots, especially on hot days. A 2- to 3-in. layer of mulch helps soil moisture and temperatures remain cool, calm, and collected. Keep in mind that dark mulches, such as dyed black wood chips and black lava rock absorb (and retain) more heat. Light-colored mulches, such as shredded cedar bark and dried grass clippings, reflect heat and help soil stay cooler.

Water right

Offer bedded annual plants at least an inch of water a week. Containers need more, because they are above ground and more susceptible to drying winds. Use a drip system or soaker hoses for consistent (and easy!) watering. You can even use drips in containers. Hook everything up to a timer, so that watering is automatic and effortless. Water in the early morning for less evaporation.

Provide shade

Adding shade-producing trees, shrubs or structures to your landscape helps lower surface temperatures and reduces heat in your yard. Shaded surfaces can be up to 20 to 45 degrees F cooler than unshaded materials in the same area. In midsummer, when the sun is most intense, coleus (Plectranthus hybrids) and sweet potato vine (Ipomoea batatas) may wilt; but you can offer relief in especially hot spots in your yard by adding temporary fabric row covers or shades. UV-stabilized, polyethylene shade net reduces effects of summer sun yet allows air flow. Planting heat-susceptible plants on the north or northeast side of a taller, more heat-tolerant plants, such as Mexican sunflower (Tithonia rotundifolia) or zinnia (Zinnia elegans), can give a little shade during the hottest part of the day.

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How heat and drought affect plants

Some plants are naturally more resistant to heat, humidity and drought than others and these flowers can take heat better. For example, species that are native to hot, dry climates have developed a number of tricks that allow them to survive the blazing heat, such as thick cuticles (think cacti) or waxier leaf surfaces (think agaves) that result in lower transpiration rates. Other plants minimize water loss through transpiration by having smaller leaves, leaves covered with fine hairs or by developing wider or deeper root systems. Transpiration is essentially how plants sweat; their pores, through which hydration is lost, are called stomata. When plants lose water, they wilt.

Illustration of how transpiration works on plant leaves

How transpiration works

During transpiration, moisture is absorbed through the roots, carries nutrients up through the plant and exits through the stomata when they exchange carbon dioxide from the air for water vapor. When too much moisture leaves, plants wilt. Some plants have characteristics to slow this process as mentioned above.

6 Summer flowers that can take the heat

Here are 6 flowers that are well-adapted to heat and drought. They’ll keep blooming and look good even when other plants struggle.

Angelonia (Angelonia angustifolia)

Talk about standing up to heat and humidity. Angelonia is native to Mexico so it evolved to take hot temperatures. Thanks to its upright growth habit and wand of color, angelonia is the ideal plant for a dose of bright color. Use it in beds, borders or containers. Some varieties offer sweet fragrance. Archangel™ Blue Bicolor (in photo) features huge flowers and beautiful deep purple and light lilac blooms atop small green leaves.

Type Tender perennial (usually grown as an annual) Blooms White, purple, lavender, blue, pink, red and bicolors from summer through autumn Light Full sun Soil Well-drained Size 12 to 30 in. tall, 10 to 18 in. wide Hardiness Cold hardy in USDA zones 9 to 11

French marigold (Tagete spatula)

One of the standby picks for hot gardens, marigolds add perky color and adorable, vase-worthy blooms and the small leaves help prevent moisture loss in summer. Easy to start from seed or buy in flats, French marigolds are a classic. But stand back for a showy new variety: ‘Strawberry Blonde’ (in photo) breaks the mold with blooms in apricot, rose and yellow. In cooler temps, flowers are pink-plum. As the summer heats up, the blooms change to yellow-pink. Plant in containers or mass in beds for a spectacular show.

Type Annual Blooms Orange, yellow, red, apricot or white from summer through autumn Light Full sun to part shade Soil Well-drained Size 6 to 12 in. tall and wide

Petunia (Petunia x hybrida)

Petunias are fast-growing, gorgeous and low-maintenance: Their small, hairy leaves help them conserve moisture. Whether in beds or containers, these versatile bloomers flower happily in hot weather as well as cool. Plus they come in nearly every color of the rainbow. Easy Wave® petunias are spreaders, but have more of a mounded shape and controlled spread than the original Wave®. Try Easy Wave White (in photo) in containers or as a pathway edger; they’ll help illuminate walkways even after dark.

Type Tender perennial (usually grown as an annual) Blooms Yellow, pink, lilac, purple, coral, red, fuchsia, white or bicolors from spring through autumn Light Full sun Soil Well-drained Size 4 to 24 in. tall, 8 to 96 in. wide Hardiness Cold hardy in USDA zones 10 to 11

Creeping zinnia (Sanvitalia procumbens)

Creeping zinnia is one of those handy plants that you can tuck in anywhere: They add sunny yellow color to pots or at the edge of borders. And because of their trailing habit and low water needs (helped by the small hairy leaves), they spread their joy. Tsavo Yellow Compact creeping zinnia (in photo) is tidy and mounding so it’s an especially great choice for containers; the dark green foliage is a nice contrast with the yellow blooms.

Type Annual Blooms Yellow from late spring through autumn Light Full sun Soil Well-drained Size 4 to 12 in. tall, 9 to 18 in. wide

Moss rose (Portulaca grandiflora)

Hot, dry, poor soil? That’s no problem for moss roses. These little bloomers will sprout anywhere, even in the cracks between bricks. Great for containers, these beauties with fleshy leaves that conserve moisture will often reseed themselves. So while they are annuals in colder climates, you may be enjoying them for years in warmer ones. Another plus is that deer don’t like them. Mojave® Red moss rose (in photo) features large rosy flowers with delicate yellow stamens. It is a vigorous rebloomer that doesn’t need deadheading.

Type Tender perennial (usually grown as an annual) Blooms Red, orange, pink, yellow or white from summer through autumn Light Full sun Soil Well-drained Size 3 to 10 in. tall, 6 to 18 in. wide Hardiness Cold hardy USDA zones 9 to 11

Sedum (Sedum rupestre)

Sedums enjoy the well-deserved reputation for being able to take heat and drought with grace — thick, fleshy leaves store moisture. Available in annual, tender perennial and hardy perennial options, sedums should be your go-to choice for hot spots. For a splash of color, try Lemon Coral sedum (in photo). It doesn’t flower like its relatives do, but its beautiful chartreuse foliage pairs well with most other plants in containers.

Type Perennial Blooms Yellow flowers in summer Light Part shade to full sun Soil Well-drained Size 3 to 10 in. tall, 10 to 24 in. wide Hardiness Cold hardy in USDA zones 3 to 10

Angelonia (Angelonia angustifolia)

Talk about standing up to heat and humidity. Angelonia is native to Mexico so it evolved to take hot temperatures. Thanks to its upright growth habit and wand of color, angelonia is the ideal plant for a dose of bright color. Use it in beds, borders or containers. Some varieties offer sweet fragrance. Archangel™ Blue Bicolor (in photo) features huge flowers and beautiful deep purple and light lilac blooms atop small green leaves.

Type Tender perennial (usually grown as an annual) Blooms White, purple, lavender, blue, pink, red and bicolors from summer through autumn Light Full sun Soil Well-drained Size 12 to 30 in. tall, 10 to 18 in. wide Hardiness Cold hardy in USDA zones 9 to 11

Creeping zinnia (Sanvitalia procumbens)

Creeping zinnia is one of those handy plants that you can tuck in anywhere: They add sunny yellow color to pots or at the edge of borders. And because of their trailing habit and low water needs (helped by the small hairy leaves), they spread their joy. Tsavo Yellow Compact creeping zinnia (in photo) is tidy and mounding so it’s an especially great choice for containers; the dark green foliage is a nice contrast with the yellow blooms.

Type Annual Blooms Yellow from late spring through autumn Light Full sun Soil Well-drained Size 4 to 12 in. tall, 9 to 18 in. wide

French marigold (Tagete spatula)

One of the standby picks for hot gardens, marigolds add perky color and adorable, vase-worthy blooms and the small leaves help prevent moisture loss in summer. Easy to start from seed or buy in flats, French marigolds are a classic. But stand back for a showy new variety: ‘Strawberry Blonde’ (in photo) breaks the mold with blooms in apricot, rose and yellow. In cooler temps, flowers are pink-plum. As the summer heats up, the blooms change to yellow-pink. Plant in containers or mass in beds for a spectacular show.

Type Annual Blooms Orange, yellow, red, apricot or white from summer through autumn Light Full sun to part shade Soil Well-drained Size 6 to 12 in. tall and wide

Moss rose (Portulaca grandiflora)

Hot, dry, poor soil? That’s no problem for moss roses. These little bloomers will sprout anywhere, even in the cracks between bricks. Great for containers, these beauties with fleshy leaves that conserve moisture will often reseed themselves. So while they are annuals in colder climates, you may be enjoying them for years in warmer ones. Another plus is that deer don’t like them. Mojave® Red moss rose (in photo) features large rosy flowers with delicate yellow stamens. It is a vigorous rebloomer that doesn’t need deadheading.

Type Tender perennial (usually grown as an annual) Blooms Red, orange, pink, yellow or white from summer through autumn Light Full sun Soil Well-drained Size 3 to 10 in. tall, 6 to 18 in. wide Hardiness Cold hardy USDA zones 9 to 11

Petunia (Petunia x hybrida)

Petunias are fast-growing, gorgeous and low-maintenance: Their small, hairy leaves help them conserve moisture. Whether in beds or containers, these versatile bloomers flower happily in hot weather as well as cool. Plus they come in nearly every color of the rainbow. Easy Wave® petunias are spreaders, but have more of a mounded shape and controlled spread than the original Wave®. Try Easy Wave White (in photo) in containers or as a pathway edger; they’ll help illuminate walkways even after dark.

Type Tender perennial (usually grown as an annual) Blooms Yellow, pink, lilac, purple, coral, red, fuchsia, white or bicolors from spring through autumn Light Full sun Soil Well-drained Size 4 to 24 in. tall, 8 to 96 in. wide Hardiness Cold hardy in USDA zones 10 to 11

Sedum (Sedum rupestre)

Sedums enjoy the well-deserved reputation for being able to take heat and drought with grace — thick, fleshy leaves store moisture. Available in annual, tender perennial and hardy perennial options, sedums should be your go-to choice for hot spots. For a splash of color, try Lemon Coral sedum (in photo). It doesn’t flower like its relatives do, but its beautiful chartreuse foliage pairs well with most other plants in containers.

Type Perennial Blooms Yellow flowers in summer Light Part shade to full sun Soil Well-drained Size 3 to 10 in. tall, 10 to 24 in. wide Hardiness Cold hardy in USDA zones 3 to 10

Published: Aug. 6, 2020
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