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.”

Old Garden Roses take heat, humidity

Cecile Brunner, also called the sweetheart rose, is an excellent choice for Louisiana gardens. Photo courtesy of Texas A&M.

Do you like antiques?

Then you should have some in your garden.

Old Garden Roses are cultivars that were developed before 1867, the year the first hybrid tea rose was released.  Many are fragrant, disease resistant and have a form that fits nicely into a landscape planting, especially a cottage garden.

There are about a dozen in my yard, and I love them. If you’d like some too, check out these recommendations for the best old garden roses for Louisiana as recommended by the New Orleans Old Garden Rose Society and share by LSU AgCenter horticulturist Allen Owings. They’re broken into two categories: The Must Haves/Never Fails and Others to Consider. Most fall into the china, tea, polyantha and noisette groups, which can take the heat and humidity Louisiana has an endless supply of in summer.

They are:

Must-have climbers:

  • Prosperity: hybrid musk, white and everblooming.
  • Climbing Pinkie makes is capable of climbing on your house. Photo courtesy of Allen Owings.

    Climbing Pinkie: polyantha, pink, everyblooming. “This one is a pretty aggressive grower,” Owings said. “It will climb on your house.”

  • Reve d’Or: noisette, apricot, everblooming.
  • Climbing Cramoisi Superieur: china, dark red, everblooming.

Other climbers to consider:

  • Crepuscle: noisette, gold and dark pink, mannerly climber.
  • Celine Forestier: noisette, soft yellow, mannerly climber.
  • Buff Beauty: hybrid musk, gold.
  • Mme. Driout: climbing tea, light pink with darker pink stripes.

Must-have large bushes (over 6 –feet tall)

  • Mr. B.R. Cant: tea, large deep pink, everyblooming.
  • Marie Van Houtte: tea, creamy yellow, everblooming.
  • Duchesse de Brabant: tea, light pink, everblooming. (I love this one.)
  • Cecile Brunner (also called the sweetheart rose): polyantha, small pink, everblooming.
  • Bermuda Kathleen: china, single flowers that change color, everblooming.
  • Safrano: tea, cream, everblooming.
  • Mutabilis (also called the butterfly rose): china, large single flowers that change color, everblooming.
  • Maman Cochet: tea, pink, everblooming.

Other large bushes to consider:

  • Baronne Henriette de Snoy:  tea, creamy pink blend.
  • Mme. Issac  Pereire: bourbon, dark crimson.
  • White Maman Cochet: tea, white with blush edges.
  • Niles Cochet: tea, medium pink center with darker outer petals.
  • Mme. Berkeley: tea, salmon pink gold blend.

Must-have medium bushes: (3- to 6-feet tall):

  • Louis Phillippe: china, dark red, everblooming.
  • Alexander Hill Gray: tea, soft yellow, everblooming.
  • Ducher: china, pure white, everblooming.
  • Caldwell Pink: found rose, bright pink, everblooming.

Madame Joseph Schwartz is white flushed with pink. Photo by Kathie Rowell.

Other medium bushes to consider:

  • Mme. Joseph Schwartz: tea, cream white with pink picotee. (This is another of my favorites.)
  • Souvenir de Francois Gaulain: tea, dark purple-red.
  • Le Vesuve: tea, pink.
  • Theresa Bugnet: rugosa, light pink.

Small bushes (under 3 feet):

  • Souvenir de la Malmaison: bourbon, light pink, everblooming.
  • Perle d’Or: polyantha, small apricot, everblooming.
  • Martha Gonzalez: china, single red, everblooming.

Other small bushes to consider:

  • Kronpressin Viktoria: bourbon, pure white, sport of Souvenir de la Malmaison.
  • Souvenir of St. Anne’s: bourbon, flesh pink, single to semidouble, sport of Souvenir de la Malmaison.
  • Hermosa: china, soft pink.

Do you grow antique roses? What are your favorites?











Spring-flowering trees

The Taiwan flowering cherry tree in my yard is just beginning to bloom. Photo by Kathie Rowel

Our flowering cherry tree just finished blooming.

The early-blooming varieties of Oriental magnolia may have been ruined by the hard freezes we’ve had recently, but my late-bloomer still looks good.

It won’t be long until all of Louisiana takes on the pastel colors of a Monet painting.

Can you tell I love spring-flowering trees? I’d plant a forest of them if I had room.

And I’m not the only one.

“There are few spring- flowering trees that I don’t like,” said retired LSU AgCenter area horticulturist Denyse Cummins. “If I don’t like it, it’s because I’ve never seen it.”

If you’d like to add one – or a dozen – to your yard, check out these recommendations for Louisiana’s best :

DenyseCummins, LSU AgCenter horticulturist

  • Redbud – “Common and a little weedy but nothing like it in the early spring, especially in a woodland setting. There are a few terrific new varieties with double flowers that I saw in Dallas and hope to track down.”
  • Japanese magnolia Sundance. Photo courtesy of Denyse Cummins.

    Any Japanese magnolia or hybrid magnolia cross. “Galaxy has huge flowers. I am fascinated with the yellows and have not given up on them but have yet to see one that totally wows me. Perhaps my trees just need to get a little bigger. Sundance is here at the office, as well as Galaxy.”

  • Magnolia stellata – The Japanese saucer magnolias always steal their thunder but they are just as impressive and tough as nails.
  • Taiwan cherry – “A deep rose color, it’s the earliest of the flowering cherries. Only the spring magnolias are earlier.”
  • Okame cherry – “We have these at our office. A little later than the Taiwan cherry, they are pale pink blushed with deeper pink and absolutely lovely.”
  • Silverbell – “A Louisiana native that I have actually owned on property in Ruston as a wild tree. I’ve since bought them from nurseries. Dr. Willis of Willis Farm in Doyline has sold me some improved selections and I can’t wait to see how they do.”
  • Dogwood: “Dogwood is, of course, beloved if you grew up in the South. They used to be all over the woods in North Louisiana and have been greatly thinned out by clearing woodland for development and exposing them to too much sun to make it through dry times. They can be hard to establish but if you can get them going they are a real pleasure. Mine is red. They have had some problems with anthracnose but I think that the major issues with them are more environmental: loss of wild habitat, poor watering the first year of planting and damage to bark and drought stress on established trees. Willis Farm is selling the Tennessee varieties that have anthracnose resistance. If they die you have only yourself to blame. I killed mine by leaving town during a drought.”
  • Chinese fringe: Chinese fringe (Chionanthus retusa) so puts our native grancy graybeard in the shadows that I would not consider a grancy in my yard again. The Chinese species has a pristine white, short fringe that totally covers the tree in spring. I’ve loved it since I saw the first one.”
  • Flowering peach – “I have a white double but have seen a pink/peppermint one on my street. They are quite early and I really like to bring the branches in when they are loaded with buds and force them in the house.”
  • Chinese witch hazel:  Our native witch hazel has very insignificant blooms, but the Chinese are yellow or orange with big, fringy flowers. I have seen it well-grown in Southern gardens but unfortunately cannot vouch for it here because I keep letting drought kill mine.”

Ricky Kilpatrick, LSU AgCenter forester:

  • Silverbell.

    Silverbell: “There’s a pretty shape and form to the tree itself as well as the flowers. It’s a wonderful tree to have outside your kitchen window where you can sit and look at it.   A good alternative to a dogwood. I love dogwoods, but if you’re not in the right place or soil, a silverbell is a good alternative.”

  • Redbud:  “A big problem I run into close to the Red River is soil pH is too high for a lot of trees. Redbuds will handle a wide range of soils, including high pH.”
  • Yellow poplar: “This is a much larger tree.  It has a yellow tulip-shaped, pretty showy flowers. Not a tree you’ll plant and have flowering in three years.  It will reach 90 or 100 feet.”
  • Fringe trees or grancy graybeard: Grancy graybeards are neat.  They have a different kind of flower but they are certainly pretty.”
  • Flowering crabapple: “If I was dead set on a flowering  pear, I would look at a crabapple instead. Something native and not as bad about splitting and breaking.”
  • Buckeye: “The very first thing that the blooms is the buckeyes. Nice to put one on the back side of a flower bed.”

What’s your favorite spring-flowering tree?

Pink dogwood. Photo courtesy of Denyse Cummins.


Sasanquas add color to winter landscapes

ShiShi Gashira is a Louisiana Super Plant. Photo  by Kathie Rowell.

ShiShi Gashira is a Louisiana Super Plant. Photo by Kathie Rowell.

By Allen Owings, LSU AgCenter horticulturist

HAMMOND, La. – The sasanqua species of camellia is one of our most popular flowering shrubs for late fall through early spring. These go by the scientific names of Camellia sasanqua.

Sasanquas are typically smaller growing than plants that we normally call camellias. They also have finer-textured foliage. They bloom from mid-October through December or January. Sasanquas are abundant these days due to the popularity of the variety ShiShi Gashira.

ShiShi Gashira is the most popular of the dwarf-type camellias for Louisiana landscapes. These-smaller growing plants reach 4 to 5 feet in the landscape. Flowers are rose pink.

ShiShi Gashira is actually another species of camellia, technically Camellia hiemalis. This species sometimes blooms earlier than the sasanqua species and is also more cold hardy.

Leslie Ann. Photo by Kathie Rowell.

Leslie Ann. Photo by Kathie Rowell.

Popular camellia sasanquas in Louisiana are Bonanza, Yuletide, Stephanie Golden, Leslie Ann and Sparkling Burgundy.

New to the plant market a few years ago is the great October Magic series of Camellia hiemalis developed by Bobby Green of Green Nurseries in Fairhope, Ala. Plants include October Magic Bride, October Magic Dawn, October Magic Inspiration, October Magic Orchid, October Magic Rose and October Magic Snow.

Bride is a small, very double, pure pink flowering shrub with a dense conical growth habit. Mature size is 4 to 6 feet tall by 3 to 4 feet wide. This variety is a profuse bloomer.

Dawn has large rose-form flowers. Blooms are blends of pink and resemble flowers of a Camellia japonica. Plants reach 4 to 6 feet tall and 3 to 4 feet wide. The variety is great for a single specimen planting or for use as an intermediate hedge. Plants have dark green foliage.

Yuletide. Photo by Kathie Rowell.

Yuletide. Photo by Kathie Rowell.

Inspiration is a favorite. It has large double flowers that are white with a narrow maroon margin. New spring foliage is maroon. Plants reach 6 to 8 feet tall and will be 4 to 5 feet wide when mature.

Another favorite is Orchid, with white to blush small semidouble flowers that have orchid pink shades to the petals. Many blooms cover this plant. Plants reach 3 to 5 feet tall and 3 to 4 feet wide.

Rose has small very double salmon-rose blooms. This plant is an early bloomer and has a columnar, dense, upright habit. Plants reach 6 to 8 feet tall and 3 to 4 feet wide.

Snow has large, double, white flowers with a magenta edge. New spring foliage is copper tinged. Plants are compact and mounding but reach 5 to 7 feet tall and 4 to 5 feet wide at maturity.

Success with sasanquas and other dwarf camellias depends on the planting site. Part sun to part shade is best, especially for younger plants. Choose a location that receives four hours to six hours of direct sun in the morning and shade in the afternoon or a spot that receives light, dappled shade throughout the day.

When planted in full sun, sasanquas are subject to more stressful conditions. The foliage sometimes has a yellowish look, and flower buds may not open properly. Plants in full sun also may be more susceptible to injury in freezing weather.

Good drainage also is essential. Do not plant camellias in areas that are poorly drained or where water settles after a rain. If an area has poor drainage, plant camellias on mounds or in raised beds.

These plants are acid-loving, and an alkaline soil (pH above 7) can limit their ability to obtain some nutrients, especially iron. When you are preparing the area for planting, you should incorporate a soil acidifier to help make the soil more acid if your soil is alkaline. Three readily available materials for this are ground sulfur, iron sulfate (copperas) and aluminum sulfate. Copperas should generally be used because it is faster acting than sulfur and provides additional iron.

Fertilize in the spring as new growth begins – about March or early April. Use a fertilizer labeled for acid-loving plants or any general-purpose fertilizer according to the manufacturer’s label directions.

Sasanquas and camellias are part of our Southern gardening heritage. A few well-placed specimens will brighten up your landscape during these late fall and early winter days when few other shrubs are blooming.