JARS v61n4 - Growing Rhododendrons In Oklahoma and Texas

Growing Rhododendrons In Oklahoma and Texas
Keith Johansson
Arlington, Texas

It was not until I bought a renovated 1928 two-story brick house in Tulsa, Okla., in 1985 that my passion for plants, especially rhododendrons, came to life. I grew up in Bartlesville, Okla., and played in my parent's l-acre Oriental style garden of azaleas, lanterns, ponds, maples, and bamboo in the '60s. I also worked five years in a nursery after school, but my Tulsa home, which was two blocks from the Tulsa Garden Center, Woodward Park, and Philbrook, needed new landscaping. I studied hard and determined that one of the shrubs already in the garden was a rhododendron and I wanted a few more. While waiting for twelve plants to arrive from Oregon, my wife, Jeri, noticed someone was to speak at the Tulsa Garden Center about rhododendrons and convinced me to go. It was Leonard Miller from Grove, Okla., and he told me how he grew them in raised beds of pine bark.
That first summer all the rhododendrons grew well and set buds. I had 'Blue Peter', 'Scintillation', 'Anah Kruschke', 'Trilby', 'Nova Zembla', 'Gomer Waterer', 'Purple Splendour', 'Emasculum', and 'Ramapo'. That first winter produced a terrible ice storm and temperatures went down to -5°F, yet all the rhododendrons, except 'Trilby', looked great. Later that spring 'Trilby' grew all new leaves and looked good too.
Shortly thereafter the Ozark Chapter was chartered. Leonard was our first president and he already had an impressive collection, and later became the ARS president and built Lendonwood Gardens, with the best collection of my favorite plants in the Midwest. Dr. John C. Pair, researcher and director, Kansas State University, was also a member and was doing research with rhododendrons in Wichita. Sue Mohr in Clinton, Ark., had over a hundred varieties and many were 12 feet tall. Ronnie Palmer in Pine Bluff, Ark., had large ones too and even operated an azalea nursery with hundreds of varieties. John Thornton in Franklinton, La., amazed us when we saw his nursery and hybridizing work with the heat tolerant Rhododendron hyperythrum . These early blooming hybrids have nice foliage and are hardy and heat tolerant. (Forty of his named hybrids will be available at the Tulsa Convention.) The Ozark Chapter covered a five-state area and when we came together it was always fun. We never stop talking about growing rhododendrons and the only arguments are over who killed the most.
The oil-based Oklahoma economy soured in 1989 and that's when I dugup my rhododendrons and moved to Arlington, Texas, which is between Fort Worth and Dallas. It took two years to find a house with a large yard, mature trees, and a favorable microclimate. I quickly built eight 20-foot-long beds, some wide enough to plant them three deep, and piled over 500 bags of pine bark 2 feet deep and soon had 120 rhododendrons growing. Rhododendrons grow huge root systems, probably from the heat, so always use lots of bark. I also grew everything else, like dinner-plate size dahlias, kalmias, huge tomatoes, etc. Tijs Huisman, a hybridizer from the Netherlands and a speaker at the Tulsa convention, sent rhododendron cuttings of 'Simona', 'Libretto', 'Maharani' and others that I rooted and got to bloom. I have always loved starting new plants and my wife still claims that I once rooted firewood.
I began collecting azaleas and Japanese maples as companion plants. Many of my 300 varieties of azaleas came from cuttings from the Dallas Arboretum where 2,000 varieties had been planted. I developed a special fondness for Satsuki azaleas and have over 100 varieties. I like to use Satsuki in the foreground, and both weeping maples and smaller rhododendrons in the middle, and the taller rhododendrons, azaleas and upright maples in the back.
Most of the rhododendrons grew well, but as I became more adventurous, varieties like 'Manda Sue', 'Lem's Cameo', and 'Mars' would not grow in the harsh Texas climate no matter what I did. Some, like 'Solidarity', would lose their flower buds in mild winters. 'Purple Splendour' had been doing well for me for nine years, and then it fall bloomed and during a mild winter it set more buds and bloomed again in spring. It then failed to break dormancy and died that July. 'Lem's Monarch', 'Point Defiance', and 'Taurus' made it through eight years, but never bloomed. I was having success with varieties like 'Roseum Elegans', 'Tiana', 'Janet Blair', 'Wheatley', 'Anah Kruschke', 'Vulcan's Flame', 'Nova Zembla', 'David Gable', 'Catawbiense Grandiflorum', 'Graf Zeppelin', 'Yaku Angel', and many of the R. degronianum ssp. yakushimanum and R. hyperythrum hybrids. 'Emasculum', a R. ciliatum and R. dauricum hybrid, lived for twenty years and more than once a neighbor asked me what kind of dogwood it was.

Rhododendron makinoi Rhododendron adenopodum
Rhododendron makinoi
Photo by Keith Johansson
Rhododendron adenopodum .
Photo by Keith Johansson
Rhododendron 'Peppermint Twist'
R. 'Peppermint Twist'
Photo by Keith Johansson

The Ozark Chapter has visited every public garden in our area and has donated rhododendrons to gardens in Arkansas such as: Crystal Springs Garden, Eureka Springs, Garvin Gardens, Hot Springs, Wildwood Gardens, Little Rock, and also to Lendonwood Gardens, Grove, Okla., and to the Ruby M. Mize Azalea Garden at Stephen F. Austin University in Nacogdoches, Texas.
I was having so much fun growing plants that I briefly entertained the idea of becoming a commercial rhododendron grower but instead in 1994 started a farm called Metro Maples. Maples are easier for the average Texan to grow because they can plant them right in their soil. I currently have 15,000 plants at the nursery and have also produced and sold 12,000 rare azaleas over the years. Last spring I introduced the first cultivar of Acer truncatum , which I call 'Fire Dragon' Shantung and it will be available in Tulsa. Dr. Pair died in 1998, but not until after he got me started with Shantung maples. I also will bring a new Japanese maple, 'Moonrise', just out of Oregon, which is a more vigorous, heat tolerant and more colorful version of the golden fullmoon maple. I stay busy, to say the least, as I get a lot of free publicity as the only maple farmer in the state and the only public place with rhododendrons.
The last six years my maple farm has demanded all my attention so my rhododendrons at home have been neglected. I do turn the sprinklers on about every three days, and deadhead them, but they receive nothing else. My rhododendrons at the farm in the display garden are fertilized carefully and regularly, and watered more often, and thus look much better and have more and larger flower buds. Last year was the hottest, driest ever, and my 6-foot 'Very Berry', which had been my favorite plant, lost so many limbs from high nighttime temperatures that it had to be cut all the way down to 6 inches. Other favorites that are doing exceptionally well are R. makinoi , narrow leaf form, that I've had for ten years, 'Catawbiense Grandiflorum', and R. hyperythrum hybrids 'City Park' and 'Peppermint Twist'. Even though the "neglected" rhododendrons at home need fertilizer, mulch, and more water, many have consistently produced blooms over the years. The top performers for good foliage and consistent flowers, with minimum care are: R. adenopodum , 'Anah Kruschke', one of my original plants from 1986, 'Pink Pearl', and 'Anna Rose Whitney', grown from a cutting. 'Nova Zembla' bloomed well for sixteen years but died after I moved it a third time and deserves a mention. 'Tiana' also was doing well until a huge branch crushed it during a violent storm.
Rhododendrons do grow in Texas. With care, they can be vigorous and set many large bloom buds, or with the right variety can be grown with minimal care with lots of pine bark in raised beds and regular watering.

Keith Johansson is the Ozark Chapter president and will be a speaker at the 2008 ARS Convention in Tulsa, Oklahoma.