Spring-Flowering Trees

Spring-Flowering Trees

After the last three years of climate torture, I’ve concluded that spring is my favorite season of the year. It’s the fresh start we all need. Redbuds, dogwoods, deciduous magnolias, hawthorns, peaches and plums, snowbells and silverbells, and so many other plants celebrate the arrival of spring. For nearly 40 years, SFA Gardens has been collecting woody ornamental varieties the same way someone might collect postage stamps. Watching what died, what sur-vived and what thrived is a lesson for all of us. Here are a few climate-resilient small flowering trees that get an A+ in our Pineywoods garden.

Deciduous Magnolias
There are few trees that stir the heart more than deciduous magnolias in full show. They typically bloom in late winter to early spring, and their blooms can be short-lived if a freeze occurs. Some varieties are a flowers-only display; others push flowers with a little green. The pink saucer forms of Magnolia x soulangeana have been dotting southern landscapes for over a hundred years. While some use the name Chinese magnolia or tulip tree, the latter is a poor choice for a common name. The true tulip tree is really Liriodendron tulipifera, which becomes a rather large tree and blooms late after the foliage has emerged.

A favorite deciduous magnolia at SFA Gardens is ‘JonJon’, which blooms a few weeks later than most saucers and features Texas-sized 10-to-12-inch blooms on a tree that reaches 30 feet. It’s a Gresham hybrid by the late Todd Gresham and was selected and named by the late John Allen Smith (Magnolia Nursery, Chunchula, Alabama). All deciduous magnolias, particularly the early bloomers, carry the risk of flowers being frozen with a late-winter freeze. Waiting all year for a big show that lasts an hour is not a selling point. Still, a big ‘JonJon’ tree viewed in full bloom is a memory. ‘Frank’s Masterpiece’, a dark-flowered form, is stunning in bloom. ‘Daybreak’ has a long season of large rosey-pink blooms on a fastigiate tree to 20 feet or more. The award-winning Magnolia x kewensis ‘Wada’s Memory’ sports seven-inch flowers, is hardy and blooms as a young plant.

The yellow-flowered varieties always generate excitement. The yellow color is derived from the native cucumber-tree magnolia, M. acuminata, as a parent. With hybridization and selection, there have been many varieties introduced touting canary-yellow flowers. For full disclosure, the heat of Texas typically results in less yellow and more cream. Still, ‘Butterflies’ is a fine yellow-flowered form that resulted from a cross between M. acuminata (seed parent) and M. denudata (pollen parent). It is noted for its non-fading yellow flowers, late vegetative growth, compact pyramidal form and hardiness to both heat and cold. ‘Golden Sun’ has been impressive.

For most of Texas, it’s best to plant deciduous magnolias in well-drained soil and to avoid full-sun exposure. A little afternoon shade is wise and avoid windy locations. Wind tends to tatter leaves, branches and flowers. In the establishment years, an even amount of moisture is preferred. For those plagued with high pH calcareous soils, it’s best to modify the entire potential root zone with composted pine bark or other acid-forming organics. Irrigation water that is high conductivity, high pH or burdened with high sodium should be avoided. While they prefer slightly acid to neutral pH, deciduous magnolias can tolerate slightly alkaline soils if well mulched and irrigated well. Once well-established, they are moderately drought tolerant.

Redbuds
We’ve had a love affair with the genus Cercis for many years. It’s hard to beat our native redbuds. With thicker leather-like leaves, ‘Oklahoma’ is well adapted to Texas and sports dark-purple flowers. ‘Traveler’s Weeper’ is a Dan Hosage find in Central Texas and should be used more. We continue to explore new varieties and we can report that the Asian species have been a rollercoaster of excitement and disappointment. While Cercis chinensis ‘Avondale’ found a fine home here in the Pineywoods, it never caught on. It’s a small-statured tree, somewhat shrubby in nature, and literally covers main branches and shoots with a carpet of dark-pink flowers. Cercis racemos, with four-foot long inflorescences, failed almost as soon as it hit our garden. It’s just too hot here for this Asian mountain plant. On the other hand, Cercis chuniana is our latest redbud thrill. It’s new in the USA and after four years at the SFA Gardens, it’s been through a very harsh test. It’s still in good shape. So we have some optimism this Asian native will stand the test of time. A very long six-inch inflorescence multiplies the floral impact.

Our native redbud has a huge range and is exceptionally durable. It is one of the harbingers of spring over much of Texas and dots landscapes and roadsides across the Gulf South. It’s one of the most popular landscape plants for reasons of flower and form. Still, when the dust settles on evaluating this genus, I’ll bet it’s best to choose our native Cercis canadensis (eastern redbud) and stick to local genotypes. The seed is easy: thirty minutes of acid scarification and then storage for six weeks moist cold will result in good germination percentages. Once dormant, they transplant readily as long as the soil is well drained and moisture and weed control are managed.

Of all spring-flowering trees, redbuds have generated significant varietal development. The breeding program at North Carolina State University has generated knockout varieties of epic beauty in spring-foliage color and interesting blooms. We have tested many of them and some work, some don’t. Most of the problems rest in the arena of chilling requirement (not enough in some years) and summer heat (bleached foliage color). Selected in North Carolina or elsewhere with higher chilling, they may underperform in Texas with milder winters. ‘Flamethrower’ has created unusual excitement, and after four years, we’re still impressed. ‘Pink Pom Poms’ is double-flowered with four times the number of petals. The new growth of ‘Rising Sun’ is golden, which transitions to yellow before settling into summer green. Yellow-foliaged plants are often frowned at by my Central Texas friends because yellow equates to chlorosis, something many of our western gardeners have experience with. I explain to them that yellow is also a color. We even have one variety, ‘Zig Zag’, that sports a distinct zigzag characteristic on every branch. I was showing it off to a group recently and someone in the crowd asked, “What else does it do?” I replied, “Well, with branches like this, what else does it need to do?”

Dogwoods
An old nurseryman friend once told me that dogwoods are related to sheep; they are born looking for a place to die. After having planted hundreds of seedlings and grafted varieties, I don’t necessarily disagree. High soil pH, poor-quality water, bad soil drainage and lack of attention to watering are often the perfect recipe for failure. In challenging locations, amend the entire potential root zone, avoid western sun, protect the trunk from mechanical damage, aim for perfect drainage and manage soil moisture the first few years. It’s no easy chore. Cornus florida is native across a wide swath of the Gulf South. It’s a poor choice for much of Texas, one of those Pineywoods treasures that defines the forest. Move it a little west and the challenges begin. Still, once well established, dogwoods are generally quite cold, heat and drought resistant. As for varieties, I can report there are many that visited our garden and then left. ‘Cherokee Princess’, a gift from Margie Jenkins years ago, has performed excellently in our area. ‘Cherokee Brave’ is the pink form, and it left the scene early. ‘Weaver’ stayed almost two decades before the -4° freeze of February 2021 made a mess in our resident forest. Major limbs of oaks, elms and sweetgums fell from the sky, and ‘Weaver’ was badly damaged. That same freeze killed six Cornus florida ssp. urbiniana dead as a doornail. This mountain dogwood with fused bracts is a beautiful tree from Mexico, but it couldn’t deal with the cold, ice and debris falling from above. A local landscaper concluded that the best strategy is to plant trees that are seedlings of local genotypes and plant more than you need. Treasure the ones that survive.

Hawthorns
As a genus, Crataegus is complicated. I remember a two-day foray in the 1980s into the wild of East Texas with Lynn Lowrey and a visitor from England with expertise in Crataegus. It was a fascinating trip with café lunch breaks that included laying out different collections of flowers and foliage on the table to help in determining identities. As the flowers are small, a magnifying glass brought up enough detail to segregate or integrate. As a horticulturist who would rather grow something than define it, I admit drifting into unconsciousness after the second day of that exercise. Counting anthers is not my talent. There are many native hawthorns that can be grown across a wide swath of Texas but are rarely encountered. Parsley haw, Texas haw, blueberry haw, mayhaw, turkey haw and others are all worthy landscape candidates.

Crataegus texana, Texas hawthorn, is rather uncommon and grows in only nine or ten counties of the south-central Coastal Plain in Texas. It enjoys forested bottomlands and river bottoms but can perform in the Post Oak Savannah of central South Texas. We have a tree in a sunny spot that has survived over thirty years. It has never failed to bloom, and it’s made a crop most years, albeit rust is an annual headache because we don’t spray. In East Texas, this tree needs strong drainage and responds well to pruning and fertilization. It’s exhibited good heat tolerance in the last three years, and epic cold snaps did no damage. Once well-established, it’s not a heavy water user and quite easily can be left to grow on its own in our Pineywoods region. West of here, I’m not so sure.

Crataegus opaca (western mayhaw) is an attractive tree with good fruit. A bottomland native, this plant is least happy in a very dry, hot location. If watered well, it can take off. There are a number of varieties sporting bigger fruit. Pretty blooms on a nice-shaped tree with edible red fruit shaped like a very small apple are the draw. Some think mayhaw jelly is the best in the world. Rust is a perpetual problem for this tree.

Crataegus brachyacantha (blueberry hawthorn) is a smaller tree with delicate foliage and wonderful flat flowers. The fruit is small but tasty and, again, rust can ruin the crop.

For all the hawthorns, a good soil situation means healthier trees, and avoiding the full blast of the afternoon sun is preferred, certainly in Central Texas. Even soil moisture in the establishment years is a good goal, and the tree appreciates a layer of mulch. If needed, prune late in the winter and shoot for an open-center form to encourage air circulation. Cedar-hawthorn and cedar-quince rust attacks hawthorns. In bad years, it can impact foliage, young shoots and fruit. It’s usually not lethal, just a visual annoyance. Fungicides can provide control. One source recom-mends removing cedar trees within two miles of hawthorns. That may be a bit much. Ignoring the problem is another choice.

Genus Prunus
Prunus is a big genus with a wide variety of ornamental varieties to choose from. Flowering peaches, plums, apricots and almonds are all in the family Rosaceae and, yes, they are prone to diseases and insects, particularly if stressed or damaged. Long life is rarely achieved. Still, for dependable performance it’s hard to beat a Mexican plum (Prunus mexicana). Our native flatwood plum (P. angustifolia) makes a fine spring show in East Texas. Prunus mume (Japanese flowering apricot) also makes a fine small tree that blooms very early, and fortunately the flowers are blessed with excellent freeze resistance. Ornamental peach varieties are in the trade, grown for flowers rather than fruit. Still, the adapted varieties recommended for fruit in Texas also make a fine show.

There are so many choices in the spring-flowering small-tree world, it’s difficult to pick just one. Don’t. Mix it up and be courageous. Finding trees at your local nursery is a good place to start. Even then, you may have trouble finding certain species and varieties. For instance, Halesia diptera (silverbell) and Styrax americanus (snowbell) are reliable natives but rarely encountered. Styrax japonicus ‘Rubrum Pendula’ is a rare weeping pinkish-flowered Japanese snowbell you won’t see locally. Nor will you see the Styrax tonkinensis or S. serrulatum at your favorite nearby nursery. All three are strong performers in our garden. Mail order may be the only way to go. Be careful, though. In a point-and-click world, whether on the phone or laptop, it’s easy to lose control. Whatever you choose, look at it as an investment in happiness.

Dr. David Creech
Director, SFA Gardens, Stephen F. Austin State University, Nacogdoches, Texas