A couple of years ago, I was walking with a friend through SFA Gardens. In one stretch, we had a patch of redbud varieties in good show, and he remarked, “Do you think redbuds might be the next crapemyrtle?” I said, “I don’t think so.”
To those who love crapemyrtles, the mere thought of something being modestly competitive to the grand “lilac of the South” is heresy. They are the summer-color champion of the Gulf South. However, my friend felt there’s a fly in the ointment. First, he felt they are tragically overused, and second, crapemyrtle bark scale might be their demise as a major nursery product line. Sure enough, over the past few years, I have to admit more and more folks are asking what is available that might be an alternative. For right now, I nominate redbuds.
At SFA Gardens, we’ve been planting redbuds since 1985 — seedlings, species and varieties. When something new hits the scene, we’ve tried to get a plant in the ground. Redbuds are native and quite happy here in East Texas, the perfect harbinger of spring. A dogwood nearby takes the show up a notch. Redbuds are popular as ornamentals because of their brilliant early spring flowers, displayed in mass on bare branches before the leaf buds emerge. For those interested in life after the apocalypse, the flowers can be eaten as a salad or fried.
After planting and observing dozens of varieties, we’ve reached a few conclusions. First, many northern varieties just don’t like it here. It is a chilling-requirement issue. The 2017 winter was very low chill in Nacogdoches, with only 375 hours <45° F. A number of varieties suffered, resulting in sparse flowering and late leaf out. Varieties carrying a little “Southern” genetic influence generally do better.
Redbuds are the genus Cercis in the Fabaceae family. There are only ten species to consider worldwide, found mainly in Asia, Europe and North America. While many in this family fix nitrogen, Cercis appears to lack the nodules and bacteria to make that happen. In Texas, Cercis canadensis is typically divided into three botanical varieties, which include:
1) Cercis canadensis var. canadensis, the Eastern redbud occurring from the Atlantic Coast to Central Texas.
2) Cercis canadensis var. texensis, the Texas redbud, is smaller and features smaller, glossier leaves with a slightly wavy leaf edge, with a range from southern Oklahoma through Central Texas to northeastern Mexico.
3) Cercis canadensis var. mexicana, the Mexican redbud, is smaller-statured and shrubbier, featuring small high-gloss, wavy-edged leaves, with a range occurring in West Texas and adjacent Mexico.
Botanists recognize there is gene mixture occurring between the three botanical varieties, certainly at the edges, and they find great joy in parsing the distinction between var. texensis and var. mexicana. To be honest, the geographic overlap of characteristics makes separating them difficult. Whether this is worthy of a heated campfire debate depends on who you are.
CARE AND CULTURE
In general, redbuds like a well-drained spot and full sun for best performance. I prefer to plant on mild berms of good loam. Waterlogged soils in the root zone are a nemesis. Once established, redbuds are generally able to make it on their own without a lot of irrigation. Experience tells us that the colorful leaf varieties don’t like the full blast of a Texas afternoon sun. In our region, high-canopy pines provide the perfect setting for a dazzling springtime show.
While generally pest free, there are problems. Poor drainage encourages a fungal pathogen, Botryosphaeria canker, which is common and can cause trunks and stems to die. Root rot is suspected to cause the decline of many urban trees. Leaf spots and Verticillium wilt can be a problem. Tree hoppers, caterpillars, scales and leafhoppers can mar a tree’s appearance but are rarely overwhelming.
The premier program for redbud genetic improvement is the breeding program of Dr. Denny Werner at North Carolina State University (NCSU). Redbuds were a passion for the late Dr. James C. Raulston, who directed the arboretum, now the JC Raulston Arboretum, and the gardens there are home to one of the great collections of the genus in the world. Dr. Denny Werner was originally the peach breeder at NCSU, and we had a connection in that area, but we both moved into the world of ornamentals for reasons that still confuse us.
I asked Denny just what it was that led him to focus on redbuds. He replied, “Well, redbuds presented all the ingredients for a successful plant-breeding venture — native species, already a widely recognized landscape plant, useful genetic variation in flower color (purple, near red, white, pink), leaf color (purple, gold, variegated) and architecture (weeping, compact). In 1988, I recognized that almost all commercial cultivars of redbud originated from chance discoveries in the wild or in commercial nursery settings. I was confident that new and unique cultivars could arise from a targeted breeding effort. That has proven to be true. Additionally, I have always had a personal passion for redbud, and having that passion has contributed to my success with this species. Being engaged in breeding efforts with this species for over 20 years has been a joy. A number of breakthrough introductions such as ‘Ruby Falls’, ‘Pink Pom Poms’, ‘Flame Thrower’ and ‘Golden Falls’ are widely accepted in the industry. There’s great satisfaction as I drive around the country and see cultivars we developed, now in garden centers, botanic gardens and in residential and home landscapes settings.”
‘Oklahoma’ remains one of our favorites, and time has proven it’s a great durable small tree for Texas. It was found in 1964 in the wild in Oklahoma, a Cercis canadensis var. texensis with vivid purple-pink flowers. Its leaves are thick, glossy and always attract attention.
‘Traveller’ is a Cercis canadensis var. texensis introduced by Dan Hosage, Madrone Nursery, near San Marcos, Texas. Dan is one of those brilliant savants of Texas horticulture. He remains a part of Texas horticultural lore. Dan is a character, one of those rare individuals you meet and never forget. ‘Traveller’ flowered for the first time in March of 1993 as a selection of some 10,000 seedlings grown from seed obtained from a wild stand in Blanco County, Texas. ‘Traveller’ is one of the most graceful of weepers. Whether high- or low-grafted, it makes a mark in any landscape.
‘Pink Pom Poms’ is unique and does well at SFA Gardens. It’s a seedling of the double-flowered cultivar ‘Flame’ redbud and was found growing in a commercial plant nursery in Belvidere, Tennessee. While it’s unproven, a nearby tree of ‘Oklahoma’ is thought to be the pollen parent, which might explain its good performance in our garden. Out of 278 seedlings, ‘Pink Pom Poms’ was selected for its glossy-green leaf color, double flowers, attractive purple-violet flower color and semi-upright growth habit. With up to fifty petals per bloom, it is one of the most asked about redbuds in our collection.
The ‘Rising Sun’, has been a solid performer. I realize golden leaves remind my Central Texas neighbors of chlorosis, but, please, gold is a color, and this variety does it well. It was discovered in 2006 by Ray and Cindy Jackson of Jackson Nursery in Belvidere, Tennessee, and its parentage remains unknown. It was recognized in a row of nursery seedlings and was selected for its heart-shaped foliage that emerges golden, maturing eventually into green. The fall foliage is less dramatic, but leaves turn yellow-orange before falling. It’s reported to be drought and heat tolerant, and we’ve concluded it’s well suited for our region of Texas.
‘Silver Cloud’ is variegated and a beacon in the spring with leaves striped and splotched with white and green. While of northern origin, it has performed well in our gardens for many years. ‘Alley Cat’ is another variegated redbud we’ve come to admire. It appears to be a bit more sun tolerant than ‘Silver Cloud’ but suffered from low chilling in the winter of 2017. Both varieties love the shade of high-canopy pines.
‘Forest Pansy’ is an old timer, a 1947 introduction that has performed admirably in Texas for years. The striking purple foliage is an eye catcher, a shiny red-burgundy dazzling display. Unfortunately, the purple foliage doesn’t last long, quickly fading into summer greens. It was found in a seedling block in McMinnville, Tennessee, and in spite of its original provenance, it remains one of the best purple-leaf forms for Texas.
‘Ruby Falls’, a Denny Werner introduction, is the first purple-leaf weeping redbud. I’ve long been enamored with the variety, and it’s particularly useful for small gardens. That said, we can report it struggled with the very low-chill 2017 winter. Bloom was sparse and leaves didn’t emerge until late in April. Eventually it recovered, but gardeners in the Gulf South might take note.
‘Merlot’ is another Denny Werner introduction, a purple-leaved cultivar of unknown parentage. The seedling was the result of a planting of ‘Texas White’ adjacent to ‘Forest Pansy’. The seedling was chosen because it combined the purple leaf of ‘Forest Pansy’ with the shorter stature and glossy foliage, heat and drought tolerance, and more upright growth habit of var. texensis. Still, we’ve been disappointed in the flower show after low-chill years.
‘Flame Thrower’ is a game changer and has been in our collection for only two years. It’s another Denny Werner introduction, a ‘Rising Sun’ x ‘Ruby Falls’ cross. The spring foliage show gave me mild heart palpitations. Spring growth is a collage of reds, dark burgundy, oranges and yellows — a definite showstopper. While it’s new in the trade, we’ve had two good spring shows in a row and have high hopes it’ll find parts of Texas to its liking.
WHAT ABOUT OTHER SPECIES?
Cercis chinensis ‘Avondale’ is more than twenty years old and still saying hello every spring in our garden. It’s a shrubby form from China and flowers early every spring with blooms running all the way down the main trunks to the ground, a tendency referred to as cauliflory. Cercis siliquastrum, the Judas tree, has performed poorly in our garden. It’s a small deciduous tree from Southern Europe and Western Asia, and legend has it that Judas Iscariot hanged himself from this tree, which caused its flowers to turn from white to red.
There are a couple of rare Chinese species just now finding their way into botanical gardens and breeding programs, mainly because of the work of plant explorers and botanical explorations. We attempted C. racemosa years ago, but it hit our Texas summer and committed suicide. It’s unique because of pendulous 2–4” chains of white, light-pink or dark-pink flowers. Cercis chuniana has the same pendulant flowers and is being tested in Gulf South. Scott McMahan, the Manager of International Plant Exploration at the Atlanta Botanical Garden, is enthralled by the species. Scott said, “I think what excites me most about this genus is the fact there are still valuable characteristics found in wild species that are just now being evaluated here. Cercis chuniana is a great example of a species that was described in 1940 but was completely absent from collections outside of China until we collected seed in 2014. When you start thinking of all of the potential hybrids that could be created by incorporating some or all of these unique traits, it begins to boggle the mind.” I agree.
There is a world of new redbud varieties entering the market. I am convinced they are going to shake up how we think about and use redbuds in our landscapes. The opportunity to pick varieties for a specific tree form, flower color or leaf color is here. Let’s keep planting. tg
Dr. David Creech
Director, SFA Gardens, Stephen F. Austin State University, Nacogdoches, Texas