JARS v51n1 - LenDonwood Garden

LenDonwood Garden
Leonard O. Miller, D.D.S.
Grove, Oklahoma

LenDonwood is the extension of my ongoing love affair with gardening. It moves my private garden effort to a public botanical garden. LenDonwood is an affiliate member of the Oklahoma Botanical and Arboretum System, which has 11 other public gardens in the state of Oklahoma. This group has as its purpose to educate the public in horticulture. To qualify you must be open to the public, use good horticulture practices, educate and inform. All plants must be labeled. The Oklahoma botanical gardens are diversified with all aspects of gardening represented. LenDonwood offers unusual and rare plants that survive and grow in this unique location of Grove, Okla. Our location is at the corner of several regions. We are officially in the Southwest region of the United State; however, we are near the corners of the Midwest and the Southeast. This allows us some latitude for our plant selection. Our garden is located in the southern area of USDA Zone 6. Our 25-year low was -14°F. The summers usually have five days of over 100°F with high nighttime temperatures. In 1983 we had 50 days of over 100°F. Our rainfall is 42 inches per year falling mostly in the spring and fall. We usually have less than 20 inches of snow, which melts quickly. As most Midwest gardeners will tell you, "It's not the cold or the hot that is hard on plants. It's the rapid change of temperature that plays havoc with ornamentals."
When you build a public garden you have different considerations than when you are building a garden for yourself and your family. You must make it accessible to handicapped individuals. Walkways should be wide enough to accommodate two people side by side. There should be a front entrance with a parking area. You may want to have someway to collect revenue. We added a metal donation box. The garden should be an educational experience.
Building a garden is about finding the plants and structures that fit your soil, exposure and your water availability. These environmental factors limit the type of garden you can construct. The last, but not least, consideration is financial. Small public gardens open and close much like any small business. My garden is like my vacation home, both financially and recreationally. I really enjoy growing plants and meeting people. What better way to meet people who have the same interest!
In selecting plants for your garden you must take a look at your soil and exposure. Here at LenDonwood we have what I call "acid rock." It is an ideal site for trees because of the good drainage of rocky soils. Large oaks grow here and I trimmed them to give us high shade. This open shade allows us to grow many plants that flourish on the East and West coasts. In Oklahoma, we do not have many cloudy days and the sun dries the soil very quickly. Mature trees buffer this exposure. Surface rooting trees such as hackberries, elms and sycamores were eliminated.
My interest in rhododendrons began when I saw in full bloom a 12-foot high rhododendron at Calloway Gardens in Pine Mountain, Ga. I have been trying for 25 years to raise a plant of that stature, and I must admit I haven't succeeded. Most of my early attempts to grow rhododendrons had limited success. Rhododendrons planted in peat moss lived a few years and then died. The peat moss was too wet particularly in the winter. Azaleas, on the other hand, loved Oklahoma's heat and humidity. I collected 250 different varieties in a short time and planted them in my front yard. Twenty-five years later, the Gable azaleas are the backbone of our azalea garden. Other azaleas that have prospered are 'Delaware Valley White', the Schroeder group, Robin Hills, and the Girards. Some Glenn Dales have survived including one of my favorites, 'Allure'. Another azalea from the Schroeder hybrids that is outstanding is 'Carrie Amanda'. My azalea garden does not have the most favorable site, a south facing hillside. Early azaleas are often damaged from a late frost or killed by a freeze. The Girard azaleas that bloom mid season to late could be an answer to this problem. The Robin Hills have been successful, but they are relatively new to our garden. The azalea garden now has 300 varieties of azaleas and over 1,000 azalea plants. The azaleas are so colorful they attract a lot of attention.

Evergreen azaleas in the 
author's private garden
Evergreen azaleas in the author's private garden, which is
adjacent to the public garden and open to the public in the spring.
Photo by Leonard O. Miller

My success with elepidote and lepidote rhododendrons came after Ohio State University research showed that rhododendrons could resist phytophthora, a soil fungus, by incorporating in the planting medium hardwood or pine bark. In 1984 I used 100 cubic yards of pine bark to build a rhododendron garden. The plants were set in the bark on top of the ground without digging any holes. It was one of the easiest gardens I have ever built. Two hundred plants were obtained from different sources. Not all of them liked our heat. In general those plants in the H-1, H-2 range which survive in the East do well in the Southwest. There are 150 plants remaining after 10 years. Most of the hardy Dexters do well but are slow to flower. 'Scintillation' is our best overall plant for the open woodland, but it is not a good foundation plant because it will quickly reach 6 feet and overpower other plants. It may expand out of the shade of a building, causing its leaves to burn.
David Leach's plants have some success, especially 'Bravo!', a large plant with big trusses of pink flowers. 'Rio' shows real promise with its pink and yellow flowers. My favorite tall hybrid is 'Edmond Amateis', a nice white with a maroon throat. It seems to like it here in Oklahoma. The popularity of the Rhododendron yakushimanum hybrids is due to their dense leaf and profuse flowering habit. In the South, heat distresses the flowers of late blooming rhododendrons, but yak hybrids flower early in the cooler weather. Most hybrids are heat tolerant. The yakushimanum species do not live in hot climate. Koichiro Wada could not grow them at his nursery on the southwest coast of Japan. He would put his beloved plants on a train and send them to the mountains for the summer. Yet yakushimanum selections 'Yaku Angel', 'Mist Maiden' and 'Ken Janeck' and hybrids 'Mardi Gras', 'Tanana' and 'Sneezy are doing well here in the heat. 'Mist Maiden' is growing well in Keith Johannson's garden in Arlington, Texas.
I started planting John Thornton's R. hyperythrum hybrids about six years ago. These rhododendrons are superior to most hybrids that I have found to date. Rhododendron hyperythrum crossed with the Ironclads and other species have created very good plants for our climate. Most of John Thornton's earlier crosses produced pink bud opening to white flowers, but presently he is producing nice pinks and pink and white bicolors. They are my best foliage plants too. These plants are hardy to the -10°F to -15°F range. One dwarf hybrid is called 'City Park'* ( R. hyperythrum x R. metternichii [now R. degronianum ssp. heptamerum ]) because it is sold in the New Orleans city park in the spring.

R. 'City Park'
R. 'City Park'* ( R. hyperythrum x
R. degronianum
ssp. heptamerum ).
Photo by Leonard O. Miller

In the fall of 1994, I began to build LenDonwood Botanical Garden. I had three acres of available land adjacent to my own private garden. It was an opportunity to offer the public plants that had not been seen before.
As you enter the garden you are surrounded by a wooden fence built Japanese style. There is a small roof over the fence, which offers a buffer to the plants from our high spring winds. Most of the botanical garden is styled as a Japanese stroll garden. The first area is our Display Garden. There you will find one of the largest collections of Chamaecyparis in the United States. The garden offers about 90 varieties. Chamaecyparis enjoys acid soil, high shade in hot climates, good drainage and moist soil. Many of the 50 varieties of Japanese maples are located in the Display Garden. Perennials and annuals keep color in this area. Rare cultivars of Eastern or Canadian hemlocks, 10 varieties of Thuja and the globe-shaped Picea pungens 'R.H. Montgomery' make the Display Garden interesting even in winter. Most of our guests are here in midsummer so I've used Althaea 'Diane', crape myrtle, and buddleia. These are great shrubs for color in the summer.

The Zen Garden.
The Zen Garden.
Photo by Leonard O. Miller

Out newest garden, the Zen Garden, is partitioned by a vertical cedar lath fence and has a floor of gravel with five large stones and a small pond. Here we display 60 bonsai, viewed through a window in the fence, which protects the bonsai and denies deer entry. We have two trained pines in this garden, one a Japanese black pine and the other a Japanese red pine, 'Dragon Eye'.
The Display Garden and Zen Garden occupy about one acre. Some of the rare trees here are the beautiful Aralia elata 'Aureo-variegata', Magnolia 'Sayonara', Acer negundo 'Flamingo', Franklinia , and Stewartia monadelpha . Most of the 25 varieties of viburnums are in the Display Garden. I have planted 300 varieties of perennials where I have good soil.

Rocks placed in the Woodland 
Rock is used extensively in the Woodland Garden
in the kassan style of stone placement.
Photo by Leonard O. Miller

The Woodland Garden is designed with large stones in the kassan style of Japanese stone placement. I have used 140 tons of limestone. Plants that thrive in shade are used and displayed. You will find 50 types of hostas, 12 varieties of dogwood, viburnum, Japanese maples (50 varieties are in the garden), and in the fall of 1995 I planted 150 different rhododendrons. Most of the rhododendrons are small and new to Oklahoma and will have to take the furnace test. Some of the most exciting are: 'Fantastica', 'Consolini's Windmill', 'Charmont'*, 'Yaku Sunrise', 'Percy Wiseman', 'Aloha', 'Minnetonka' and an unregistered hyperythrum cross with a pink and white bicolor.

The entrance to the Woodland 
The entrance to the Woodland Garden.
Photo by Leonard O. Miller

The Woodland Garden has one grass walkway with John Thornton's hyperythrum crosses on each side. This garden ends with a water barrier, a 160-foot long stream with nine pools that leads down a northeast slope. This is a great site for rhododendrons because of the cooler soil temperatures. I am testing some species such as R. caucasicum , R. calophytum var. openshawianum , R. adenopodum , R. alabamense and R. hyperythrum . Some hybrids that I am testing for heat tolerance are: ( R. williamsianum x R. yakushimanum ), 'Ingrid Mehlquest', ( R. smirnowii x R. yakushimanum ), 'Voluptuous' and a number of Hans Hachmann plants. I kid myself - there really isn't a cool place in July in Oklahoma except the frig.
I believe this is a true test garden for rhododendrons. We can test the heat tolerance, and this year it went to -12°F so we can test for cold tolerance too. The true test of a plant is how it performs in many different sites and not just one or two.
Crossing over one of the two bridges and you will be in the English Terrace Garden. This is an east slope with a series of rock lined beds in a geometrical style. The garden is dominated by the blue spruces that form the back border. Named plants such as 'Hoopsii' and 'Fat Albert' and 'Glauca' turn beautifully silver and blue in the late spring with their new growth. Magnolias enjoy full sun, such as: 'Wada's Memory', 'Edith Bogue', 'Ivory Chalice' 'Butterflies', 'Vulcan', and 'Galaxy'. Perennials, especially dwarf ones, grace the terraced beds. Roses are used to provide color in June. A tree that I have not seen growing in Oklahoma is Laburnum 'Pendulum'. I am planting it in a shady spot away from our strong southwest winds. Our last garden is the Japanese Pond Garden. I have arranged large stones along its bank and planted evergreens such as the junipers 'Blue Chip' and 'Andorra', Cedrus libani 'Sargentii', Cedrus deodara 'Silver Mist', Cupressus glabra 'Blue Ice' and 'Blue Diamond', Cupressocyparis leylandii 'Gold Rider', Pinus mugo 'Golden', and Chamaecyparis pisifera 'Lemon Thread'. A pond cypress ( Taxodium distichum var. nutans ), a favorite of the south and the largest tree in Oklahoma, was planted to dominate the landscape on the east. Deciduous trees that offer a Japanese appeal were used. My choices were Malus 'Japanese' and 'Red Dragon' and assorted Japanese maples and cherries. It is my hope that one day I can build the Golden Pavilion, a building in Kyoto, Japan, that was constructed in 1397 by the pond. I've always been a dreamer. The botanical garden covers three acres on which one thousand different rare and great plants grow, all with rose marker labels. It is open the year round, seven days a week from 8 a.m. to 5:30 p.m., while our adjoining private garden of five acres is open to the public during the month of April, including our greenhouse. If you enjoy gardening and gardeners you may want to open your garden to the general public. This garden is just two years old, but for the most part it has been very enjoyable talking to others who love plants. LenDonwood is one of the few public gardens in Oklahoma where you can see the beautiful flower and plant we call the rhododendron.

* Name not registered.

Dr. Miller, District Director for ARS District 11, authored an article on his greenhouse in the Spring 1996 issue of the Journal.