Heat-tolerant perennials

Rudbeckia Goldsturm lights up the garden in the heat of summer. Photo by Kathie Rowell

It’s hard to find perennials that strut their stuff in the blazing heat of a Louisiana summer, but they do exist.

I asked Denyse Cummins and Dr. Joe White, retired LSU AgCenter horticulturists, for their heat-tolerant perennial recommendations. (Don’t run out and plant them now, though. Put them in next spring and come next summer you’ll be sitting pretty.)

Here’s what they said:

  • Goldsturm rudbeckia: A classic black-eyed Susan, this tough plant was named the Perennial Plant of the Year in 1999 and a Louisiana Select Plant in 2000. It bears masses of golden daisies with black cones that look great both in the landscape and in bouquets. Deadhead the flowers to encourage rebloom.
  • Ruellias: Also called Mexican petunias, these lavender flowers come in both dwarf and tall forms. Because they spread by both rhizomes and seeds, they can be invasive, especially in rich soil. The named dwarf form Katie is said to be less aggressive and was named a Texas Super Star. Bonus: Mexican petunias need no deadheading.
  • Salvias: Most perennial salvias are native to the Southwest, so heat doesn’t faze them. Colors can range from red to pink to blue to white, depending on the variety. Try autumn sage (Salvia greggii), mealy-cup sage (Salvia farinacea), Black and Blue salvia (Salvia guaranitica) or Mexican bush sage (Salvia leucantha). All prefer well-drained soil.
  • Agastaches: While these are not yet widely know, Denyse thinks they should be. Their pink, lilac or purple spike flowers lure butterflies, bees and hummingbirds.
  • Lantana: This old favorite makes a mound of foliage set off by clusters of flowers in yellow, white, orange, pink, red and lavender, or often a mixture of several colors that change as the flower ages. There are dwarf, medium and huge varieties, so make sure you know which you have before you plant it. Lantanas are also known for attracting flying pretties to your garden.

“All perform very well in high heat from mid-summer into fall,” Denyse said. “A nice trick is to cut back the fading early summer-blooming agastaches, salvias and Goldsturm in midsummer and they’ll all rebloom.”

Louisiana’s Best heat-tolerant perennials

Hot weather doesn't faze Rudbeckia Goldsturm. Photo by Kathie Rowell.

Hot weather doesn’t faze Rudbeckia Goldsturm. Photo by Kathie Rowell.

It’s hard to find perennials that strut their stuff in the blazing heat of a Louisiana summer, but they do exist.

I asked Denyse Cummins and Dr. Joe White, both retired LSU AgCenter horticulturists,  for their heat-tolerant perennial recommendations. (Don’t run out and plant them now, though. Put them in next spring and come next summer you’ll be sitting pretty.)

Here’s what they said:

  • Goldsturm rudbeckia: A classic black-eyed Susan, this tough plant was named the Perennial Plant of the Year in 1999 and a Louisiana Select Plant in 2000. It bears masses of golden daisies with black cones that look great both in the landscape and in bouquets. Deadhead the flowers to encourage rebloom.
  • Ruellias: Also called Mexican petunias, these lavender flowers come in both dwarf and tall forms. Because they spread by both rhizomes and seeds, they can be invasive, especially in rich soil. The named dwarf form Katie is said to be less aggressive and was named a Texas Super Star. Bonus: Mexican petunias need no deadheading.
  • Salvia Victoria Blue

    Salvia Victoria Blue

    Salvias: Most perennial salvias are native to the Southwest, so heat doesn’t faze them. Colors can range from red to pink to blue to white, depending on the variety. Try autumn sage (Salvia greggii), mealy-cup sage (Salvia farinacea), Black and Blue salvia (Salvia guaranitica) or Mexican bush sage (Salvia leucantha). All prefer well-drained soil.

  • Agastaches: While these are not yet widely know, Denyse thinks they should be. Their pink, lilac or purple spike flowers lure butterflies, bees and hummingbirds.
  • Lantana
    Lantana

    Lantana: This old favorite makes a mound of foliage set off by clusters of flowers in yellow, white, orange, pink, red and purple, or often a mixture of several colors that change as the flower ages. There are dwarf, medium and huge varieties, so make sure you know which you have before you plant it. Lantanas are also known for attracting flying pretties to your garden.

“All perform very well in high heat from mid-summer into fall,” Denyse said. “A nice trick is to cut back the fading early summer-blooming agastaches, salvias and Goldsturm in midsummer and they’ll all rebloom.”