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Perennial rhizomatous begonias add bold texture and color to north Florida gardens

Perennial rhizomatous begonias add bold texture and color to north Florida gardens

by | Apr 23, 2020

Article by Dr. Gary Knox, Professor of Environmental Horticulture at the UF/IFAS NFREC Quincy

Introduction

Rhizomatous begonias are a large group of Begonia species, hybrids and selections characterized by large, sometimes-colorful leaves arising from thick rhizomes that grow along the soil surface. White or pink flower clusters that appear in late winter and spring are an extra bonus with these plants. Some types can be used in north Florida as herbaceous perennials that add bold leaf texture and color as well as flowers to shady gardens.

Begonia mass planting

Common rhizomatous begonias such as Begonia nelumbiifolia, ‘Erythrophylla’ (“Beefsteak”), and ‘Ricinifolia’ have long been grown outdoors in south and central Florida gardens as herbaceous perennials. North of these areas, rhizomatous begonias were considered cold sensitive and thus used strictly as pot-grown plants grown indoors or protected over winter. Nonetheless, north Florida trials testing the performance of outdoor, in-ground plantings started in Tallahassee and Gainesville as long ago as the late 1980s and early 1990s. With the proven success of some rhizomatous begonias in north Florida, interest in these plants increased rapidly in the early 2000s. Since then, savvy north Florida gardeners have been delighted by the possibility of using rhizomatous begonias as interesting herbaceous perennials for the shade garden. While temperatures below freezing can damage or kill leaves, these plants will usually produce new leaves from the rhizomes once warmer temperatures return in spring.

Plant Description Under North Florida Conditions

Leaves of rhizomatous begonias are this plant’s most distinctive feature and are why this group is so appealing to gardeners. Leaves often are large, from a few inches wide to almost 3 ft. in diameter (as reported for the cultivar ‘Freddie’ under the right conditions). Leaf shape may be rounded, star-shaped or irregularly edged, and leaf colors include burgundy, red, bronze, chartreuse, silver, and various shades of green including one so dark as to be almost black. Many types have leaves displaying patterns of one or more colors and some have silver or red markings. Undersides of leaves are often burgundy-colored, and leaf stems (petioles) also may exhibit colors other than or in addition to green. Leaves may be smooth, textured, or fuzzy-appearing due to large numbers of sometimes conspicuous hairs. Some types have leaves with an interesting three-dimensional spiral located on top of the leaf where the leaf blade attaches to the stem.

Begonia ‘Big Mac’ foliage

Rhizomatous begonia rhizomes are thickened, fleshy stems 1 to 2 in. or more in diameter that grow, branch and spread horizontally at or just below the soil surface, often in the mulch or leaf duff. Adventitious roots develop along the rhizome, and dormant buds embedded in the horizontal stem can be stimulated to grow new leaves after damage, stress or when divided. With age, as rhizomes grow outward, the oldest part of the rhizome will stop producing leaves and eventually die.

The rhizomes contain water and food reserves that allow this type of begonia to survive environmental stresses like drought as well as leaf loss or damage from cold temperatures. Shoots and roots can grow from the rhizome even if leaves and roots are killed or damaged.

Flowers occur in late winter to spring, depending on the species, cultivar and weather, and are quite showy on some selections. Flowers typically are white to various shades of pink and occur in a cluster (technically called a cyme) held above the foliage, in some cases dramatically high above the foliage. Individual flowers may range in size from 3/8-inch to over 2 inches at their widest point and a flower cluster may contain a few to over 120 individual flowers, depending on selection and growing conditions. A mature rhizomatous begonia may have an extended period of flowering, providing weeks of color. This long floral display results from large numbers of flowers developing sequentially on an individual flower cluster such that new flowers are still forming long after the first flowers have opened. Furthermore, multiple flower clusters appear over an extended time period. Flowers occasionally are pollinated and form winged seed capsules, though seed production and viability are variable. After flowering, the leaves remain a point of interest in the garden due to their size, lush appearance, interesting shapes and colorful patterns.

Cultural Requirements, Use and Maintenance

Rhizomatous begonias grow best in light shade or indirect light but can tolerate morning sun. Plants thrive in rich, organic, well-drained soil that is moist but not wet. A layer of organic mulch or leaf litter often is enough to provide basic conditions for growth in most soils if they are well-drained. Accordingly, organic mulches or leaf litter should be applied regularly around plants. Fertilizer stimulates growth but decomposing organic mulches can provide adequate nutrients, except perhaps with poor or sandy soils.

Newly planted begonias should be watered regularly. After establishment, most rhizomatous begonias benefit from regular watering but only require irrigation during periods of drought or extended dry weather.

An individual plant makes an attractive specimen plant in a container or in the garden. With time, a rhizomatous begonia can spread and, in the garden, develop into a patch. Alternatively, planting large numbers of the same rhizomatous begonia can create a very dramatic garden border, mass planting, or groundcover, especially in spring when all plants are flowering. To achieve this effect more rapidly and with smaller numbers of plants, tips of rhizomes can be pruned to stimulate rhizome branching and result in a denser plant or patch. Rhizome tip pruning should be done after plants finish flowering. Plants can be divided and moved easily since only the rhizome is needed to establish a new plant, but this should occur after flowering and early in the growing season so plants have long enough to establish before cold weather.

For aesthetic purposes, dead or damaged leaves may be removed as needed but especially after frosts and hard freezes. Similarly, leaves that overwinter often become “ratty” in appearance with time and may be removed without affecting plant growth.

Potential Problems

Rhizomatous begonias have few pests or other problems. Mealy bugs can occasionally infest plants. As with other large-leaved plants, wind or physical contact can tear and damage leaves. In north Florida, winter frosts and freezes can damage and disfigure leaves or kill leaves entirely, causing them to lose structural integrity and collapse, appearing mushy. Foliage may be protected during cold weather by frost cloth, sheets or other typical cold protection strategies, though heavy coverings could themselves damage leaves.

Rhizomes themselves usually survive cold weather because they are insulated from low temperatures by being half-buried in the ground and/or being covered by mulch. Adding mulch regularly to rhizomatous begonia plants will provide increased freeze-protection. Also, their typical planting location under tree canopies protects plants from a radiation freeze. Soil drainage is a more important factor for rhizomes since wet soil conditions could lead to rot, particularly in winter.

Common Types and their Descriptions Under North Florida Conditions

With hundreds of species and thousands of cultivars and hybrids, rhizomatous begonias can be overwhelming. Many rhizomatous begonias look alike and even experts have difficulty distinguishing species and cultivars. Many grown in north Florida have their origins in Mexico, Central and South America, though the Begonia Family is huge and species are found nearly world-wide.

Begonia heracleifolia

Technically rhizomatous begonias include Rex begonias, a group derived from Asian native, Begonia rex, and known for their especially colorful leaves. However, most Rex begonias do not grow well in Florida’s heat, high rainfall and high humidity, and so these begonias are excluded here.

Begonias listed below represent types that have proven resilient and usually cold hardy in north Florida USDA Cold Hardiness Zone 8b.

Species:

Begonia heracleifolia: The species boasts star-shaped leaves up to 6 in. across on stiff, hairy, thick leaf stems (petioles) up to 5 in. long. Each of the pointed leaf lobes is edged in dark green and has a chartreuse stripe along the central midrib, adding contrast. Spectacular sprays of pale pink flowers appear in late winter in clusters measuring 3 ½ in. by 4 ½ in. on 6-in. flower stalks (pedicels). Each cluster contains about 30 or more flowers, each about 1 in. across. As the season goes on, foliage gets showier and showier. It often dies down after winter freezes but re-emerges in late spring.

Begonia nelumbiifolia

  1. nelumbiifolia: This cold hardy begonia is known for its exceptionally large, water lotus-shaped leaves, creating a stunning specimen. Individual leaves can grow as large as 18 in. by 14 in. on leaf stems as long as 36 in. but 12 in. by 9 in. leaves are more typical. As temperatures warm, new developing foliage continues to get bigger, growing into very large leaves by fall. There also is a form in which the medium green leaves have red veining. White flowers are displayed above the foliage in mid to late spring in airy clusters measuring 7 ½ in. to more than 12 in. across on stems up to 48 in. tall. Clusters may contain as many as an astounding 120 flowers, each about ¾ in. across at its widest point.

2. popenoei: Huge rounded leaves with red veins and undersides make this a specimen plant which can grow to 3 ½ ft. tall and wide. Hardy with protection, it throws up tall stalks with clusters of white flowers in late winter.

Cultivars:

“Beefsteak”: This catch-all name refers to the original beefsteak begonia, ‘Erythrophylla’, as well as many derivatives that look similar. Beefsteak begonias characteristically have rounded leaves with a glossy green to bronze top surface and reddish undersides. Leaves range in size from 4 to 7 in. in diameter, and flower clusters are on stems up to 18 in. tall. ‘Erythrophylla’ was developed in 1847 and is considered a tough, vigorous plant, hence the common name, “beefsteak”. Given the long history and vigor, ‘Erythrophylla’ and derivative beefsteak begonias have long been shared as pass-along plants, world-wide as potted plants and later as an in-ground Florida garden plant. One type has ruddy, evergreen leaves and long-lasting, bold pink flower clusters. The scalloped 4-in leaves are on short 5 ½ in. reddish leaf stems but are most notable for remaining undamaged by temperatures down to the mid 20s °F, long after all other begonias’ leaves have turned to mush. Mid spring finds this plant topped by numerous clusters of dark pink flowers, with the display lasting 6 weeks or more. Individual clusters are about 8 in. by 5 in. on flower stems about 12 in. tall. Each cluster contains about 20 flowers each about ¾ in. wide at its widest point.

Begonia ‘Big Mac’ in flower

‘Big Mac’: This is a large, vigorous plant with enormous star-shaped leaves having reddish undertones and red leaf stems. The plant grows about 3 ft. tall and 2 ft. wide. Individual leaves may grow up to 18 in. wide on 16-in. leaf stems but typical leaves on younger plants are 10 in. to 12 in. wide. Individual white flowers are an amazing 2 in. wide at their widest point in clusters measuring 7 in. by 12 in. and containing about 75 flowers. Cold winters will knock it to the ground, but this begonia re-emerges again in late spring. This plant was hybridized in 1982 by Paul P. Lowe in Lake Park, Florida.

‘Joe Hayden’: This begonia features dramatic, dark, lobed leaves with burgundy undersides. Leaves are up to 8 in. long supported by leaf stems up to 9 in. long. In spring, the plant is topped by light pink flowers held high above the foliage. Each cluster measures about 5 in. by 7 in. on flower stems up to 26 in. tall. Each cluster contains more than 100 individual flowers, each about ¾ in. across at its widest point. This selection was hybridized in California in 1953 by Rudolf Ziesenhenne, but many similar selections have been made and are often confused with ‘Joe Hayden’.

Begonia ‘Joe Hayden’

Many other cultivars are common, but other cold hardy types suitable for north Florida include ‘Caribbean King’, ‘Caribbean Queen’, ‘Washington State’ and the catch-all ‘Ricinifolia’ types (with large, castor bean-shaped leaves). New breeding by scientists and enthusiasts promises to deliver many more types of rhizomatous begonias with increased foliage cold hardiness and an expanded range of foliage types and colors. A major Texas nursery introduced a series of rhizomatous begonia hybrids marketed as Crown Jewel Begonia™. The series currently features five patent-pending cultivars that are promoted as landscape plants for Zone 8. Additional breeding work is ongoing in north Florida.

Availability and Propagation

Rhizomatous begonias are available from Internet/mail order nurseries, some American Begonia Society members, other gardening groups, and plant societies. The introduction of trademarked rhizomatous begonias like Crown Jewel Begonia™ show promise for wider availability of rhizomatous begonias from nurseries.

Rhizomatous begonias are easily propagated by division, separation of rhizomes, or by rhizome pieces. When planting, place the rhizome or pieces (as small as 2 in. long) horizontally and half buried in a new in-ground location or in a container with potting soil. As with other begonia species, leaves may be used for propagation, though this method usually takes longer to achieve a size suitable for planting in the garden. Plants can be grown from seeds but production time is similarly long.

References:

American Begonia Society. (2020) https://www.begonias.org/index.htm. Accessed 15 April 2020.

Ginori, Julian, Heqiang Huo, and Caroline R. Warwick. (2020) A Beginner’s Guide to Begonias: Classification and Diversity, ENH1317. Environmental Horticulture Department, UF/IFAS Extension. January 2020. https://edis.ifas.ufl.edu/ep581.

Lowe, Paul. (1991) Growing Rhizomatous Begonias in the Ground in Southern Florida. Begonian 58:89. May/June 1991. https://www.begonias.org/Articles/Vol58/GrowingRhizomatousBegoniasFlorida.htm.

Schoellhorn, R. (2020) Personal communication, Alachua, FL.

Sharp, Peter G. (2011) Down to Earth – with begonias. 111 pp. http://ibegonias.filemakerstudio.com.au/PeterSharp/DownToEarthWithBegonias.pdf.

The International Database of the BEGONIACEAE. (2020) http://ibegonias.filemakerstudio.com.au/index.php?-link=Home. Accessed 16 April 2020.

UF/IFAS Gardening Solutions. (2019) Begonias. http://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/begonias.html.

Watkins, Sue. (2020) Personal communication, Tallahassee, FL.

Weekly “What is it?”: Native Azaleas

Weekly “What is it?”: Native Azaleas

by | Apr 15, 2020

The sight and scent of a wild azalea blooming in the woods can stop you in your tracks! Photo credit: Carrie Stevenson, UF IFAS Extension

From a distance, native azaleas are easily mistaken for honeysuckle vines. With long, arching stamens, you might be tempted to relive your childhood, hoping to pull the pistil from the bottom and find a single drop of sweetness on the end. Instead, upon close observation you will encounter an equally pleasurable but distinctly different scent. The wild Rhododendron canescens, known variously as a mountain, piedmont, or honeysuckle azalea, can range in flower color from white to deep pink. In northwest Florida, you will find it on the edges of swamps, or as I did on the sunny fringes of wooded areas with rich, moist soil. It is in bloom right now (March), along with its cousins, the white-blooming swamp azalea (Rhododendron viscosum) and the brilliant orange Florida flame azalea (Rhododendron austrinum).

The delicate flower of a honeysuckle azalea attracts hummingbirds and butterflies in the spring. Photo credit: Carrie Stevenson, UF IFAS Extension

Native azalea populations have declined due to wetland habitat loss, and their delightful smell and delicate flowers have made them susceptible to overcollection.  Due to these factors, the Florida flame azalea is listed on the state endangered species list and wild azaleas should never be removed from their habitat.  Native azalea species attract butterflies and hummingbirds, and are often planted in home landscapes as ornamental shrubs.  Be sure you purchase them from reputable dealers that are not collecting from the wild.

For a Unique Landscape Native, Give Needle Palm a Try!

For a Unique Landscape Native, Give Needle Palm a Try!

by | Apr 8, 2020

There aren’t a lot of quality landscape plant options that fit the description nearly every homeowner desires:  native, low-maintenance, slow-growing, pest free, drought tolerant while tolerating wet soils, loving both sun or shade, and green year-round.  Needle Palm (Rhapidophyllum hystrix) is the rare plant that checks all those boxes and deserves consideration when adding plants to your landscape!

6 year old Needle Palm in a local landscape. Photo courtesy the author

Needle Palm is an endangered native, growing in a narrow range in the coastal Southeastern US, Calhoun and Liberty counties included.  It is primarily found in the understories of wet wooded areas along slopes, ravines, and bottoms; if you’ve ever hiked the Apalachicola Ravines or Torreya State Park trails, you’ve likely encountered Needle Palm in the wild!  Being native is nice, but what makes Needle Palm an outstanding landscape option?

Needle Palm is the prettier, more refined cousin of Saw Palmetto (Serenoa repens), which it is sometimes confused with.  Unlike the rambling, aggressive, stiff-leaved palmetto, Needle palm possesses “softer”, finely cut, lustrous evergreen leaves, allowing it to add amazing texture to any landscape.  Also, unlike palmetto, it doesn’t need a yearly “cleaning” to prune out brown, dead leaves, rather its leaves persist green and clean for many years!  You might not want to reach into the interior of a Needle Palm plant anyway, as generally unseen 6-8” namesake “needles” surround the base of its trunk.  Needle Palm grows very slowly, eventually reaching 8’ tall or so, but is more often seen in the 4-6’ range in landscapes.  This is absolutely a shrub that will never outgrow its welcome.  It is a nearly trunkless palm, almost always appearing as a shrub, though with extreme old age it can begin to look a bit like a small tree with a muted trunk.  With outstanding aesthetics and a low-maintenance growth habit, Needle Palm has a place in nearly any landscape.

Mature needle palm, 6′ tall and wide. Photo courtesy the author.

In the landscape, Needle Palm does best when sited with some shade in the afternoon but also thrives in full sun.  They appreciate regular water during establishment but survive on their own without any extra irrigation after!  Needle Palm also doesn’t need much in the way of supplemental fertilization.  They do look their best with a light spring application of a general purpose, slow-release fertilizer, but this is not required.  Needle Palms are not afflicted with the pest and pathogen problems the much more commonly used non-native Sago Palms (Cycas revlolutas) attracts.  I’ve grown Needle Palm for 6 years in the landscape and have never noticed any pest or disease issues.  With Needle Palms becoming more common in the nursery trade, I don’t see a place in most landscapes for the inferior, high-maintenance, insect infested Sagos.  If you want the tropical, textured look of Sagos, plant Needle Palm instead.

Needle Palm is an extremely attractive, low-maintenance Northwest Florida native plant that you should absolutely seek out and add to your landscape!  If you want more information or have any questions about Needle Palm or any other landscape/garden topic, please give your local UF/IFAS County Extension Office a call.  Happy Gardening!

 

Post Hurricane Landscape Care: Replant Smartly with Hurricane Resistant Trees

Post Hurricane Landscape Care: Replant Smartly with Hurricane Resistant Trees

by | Nov 21, 2018

After a devastating windstorm, as we just experienced in the Panhandle with Hurricane Michael, people have a tendency to become unenamored with landscape trees.  It is easy to see why when homes are halved by massive, broken pine trees; pecan trunks have split and splayed, covering entire lawns; wide-spreading elms were entirely uprooted, leaving a crater in the yard.  However, in these times, I would caution you not to rush to judgement, cut and remove all trees from your landscape.  On the contrary, I’d encourage you, once the cleanup is over and damaged trees rehabilitated or disposed of, to get out and replant your landscape with quality, wind-resistant trees.

First, it’s helpful to take a step back and remember why we plant and enjoy trees and the important role they play in our lives.  Beyond the commercial aspect of farmed timber, there are many reasons to be judicious with the chainsaw in the landscape and to plant anew where seemingly sturdy trees once stood.  For example, trees provide enormous service to homes and landscapes, from massive cooling effects to aesthetic appeal.  Take this thermal satellite image of Hurricane Michael’s path that simultaneously shows the devastation of a major hurricane and the role trees play in the environment.

Lightly shaded area showing higher ground temperatures from loss of vegetation.

In the lighter colored areas where the wind was strongest and catastrophic tree damage occurred, the ground temperatures are much higher than the unaffected areas.  Lack of plant life is entirely to blame.  Plants, especially trees, provide enormous shading effects on the ground that moderate ground temperatures and the process of transpiration releases water vapor, cooling the ambient air.  Trees also lend natural beauty to neighborhood settings.  There is a reason people termed the hardest hit areas by Michael “hellscapes”, “warzones”, etc.  Those descriptions imply a lack of vegetation due to harsh conditions.  In this respect, trees soften the landscape with their foliage colors and textures, create architecture with their height and shape, and screen people from noise, unpleasant sights and harsh heat.

Though all trees give us the benefits outlined above, research conducted by the University of Florida over a span of ten major hurricanes, from Andrew to Katrina, shows that some trees are far more resistant to wind than others and fare much better in hurricanes.  In North Florida, the trees that most consistently survived hurricanes with the least amount of structural damage were Live Oaks, Cypresses, Crape Myrtle, American Holly, Southern Magnolia, Red Maple, Black Gum, Sycamore, Cabbage Palm and a smattering of small landscape trees like Dogwood, Fringe Tree, Persimmons, and Vitex.  If one thinks about these trees’ growth habits, broad resistance to disease/decay, and native range, that they are storm survivors comes as no surprise.  Consider Live Oak.  This species originated along the coastal plain of the Southeastern United States and have endured hurricanes here for several millennia.  Possessing unusually strong wood, they have also developed the ability to shed the majority of their leaves at the onset of storms.  This defense mechanism leaves a bare appearance in the aftermath but allows the tree to mostly avoid the “umbrella” effect other wide crowned trees experience during storms and retain the ability to bounce back quickly.  Consider another resistant species, Bald Cypress.  In addition to having a strong, straight trunk and dense root system, the leaves of Bald Cypress are fine and featherlike.  This leaf structure prevents wind from catching in the crown.  Each of the other listed species possess similar unique features that allow them to survive hurricanes and recover much more quickly than other, less adapted species.

Laurel Oak split from weak branching structure.

However, many widely grown native trees and exotic species simply do not hold up well in tropical cyclones and other wind events.  Pine species, despite being native to the Coastal South, are very susceptible to storm damage.  The combination of high winds and beating rains loosens the soil around roots, adds tremendous water weight to the crown high off the ground, and puts the long, slender trunks under immense pressure.  That combination proves deadly during a major hurricane as trees either uproot or break at weak points along the trunk.  In addition to pines, other widely grown native species (such as Pecan, Laurel Oak and Water Oak) and exotic species (such as Chinese Elm) perform poorly in storms.  Just as the trees that survive storms well possess similar features, so do these poor performers.  We’ve already mentioned why pines and hurricanes don’t mix well.  Pecan, Laurel Oak, and Water Oak tend to have weak branch angles and break up structurally in wind events.  The broad spreading, heavy canopy of trees like Chinese Elm cause them to uproot and topple over.  It would be advisable when replanting the landscape, to steer clear of these species or at least site them a good distance from important structures.

This piece is not a warning to condemn planting trees in the landscape; rather it is a template to guide you when selecting trees to replant.  Many of our deepest memories involve trees, whether you first climbed one in your grandparent’s yard, fished under one around a farm pond, or carved your initials into one in the forest.  Don’t become frustrated after a once in a lifetime storm and refuse to replant your landscape or your forest and deprive your children of those experiences.  As sage investor Warren Buffett once wisely said, “Someone is sitting in the shade today because someone planted a tree a long time ago.”

For these and other recommendations about how to “hurricane-proof” your landscape, contact your local UF/IFAS Extension Office.  Plant a tree today.

Consider American Beautyberry for Naturalized Landscapes

Consider American Beautyberry for Naturalized Landscapes

by | Oct 2, 2018

American Beautyberry Fruit.
Photo credit: Larry Williams

American beautyberry (Callicarpa americana) puts on quite a show during late summer and fall with its bright purple fruit. I have some of these plants in my landscape and they are beginning to show color now with their profusion of berry-like fruit found along the thin branches, resulting in the plant taking on a weeping habit.

Each fruit is only about 1/3 inch in diameter but collectively form roundish clusters that encircle the stems. The berries are particularly showy in September and October. They remain on the plant, even after its leaves have dropped, into early winter if not eaten by birds and other wildlife.

Many species of birds will eat beautyberry fruit including robins, cardinals, mockingbirds, brown thrashers, finches and towhees. Birds are a major method of seed dispersal for this plant.

One of my neighbors noticed my plants a number of years ago and commented, “I had never thought about using this plant in a landscape.” He grew up in Northwest Florida and had always been used to seeing American beautyberry plants growing in the wild as they are native. The plant is not well suited for manicured, formal landscapes but can be useful in a naturalized garden.

Even though I consider the showy fruit its best attribute, the small, lavender flowers tightly bunched together along the stems during June to August are attractive, as well.

American beautyberry is a deciduous shrub without much ornamental value during the winter. But during the growing season, its somewhat course, fuzzy, light-green leaves look good in a setting with other darker-leaved shrubs.

It grows well in part shade/part sun as an understory plant beneath larger trees such as pines and oaks.

Be sure to allow enough room for this sprawling shrub to develop into its mature size of three to eight feet in height with an equal spread.

It may also be used as an informal screen or even as a specimen plant. But avoid using it where it will require regular shearing as the flowers and fruit are produced on new growth.

Thinning out old or low-growing branches is a better method of pruning this plant. American beautyberry may self-seed but I have not seen this to be a bothersome problem.

America beautyberry is somewhat available in the nursery trade and is fairly easy to propagate from stem cuttings. It can be propagated from seeds, as well. In addition to the purple fruiting types, look for cultivars such as ‘Russell Montgomery’ that produce white fruit. There are also other nonnative species of Callicarpa worth looking at, such as C. dichotoma and C. japonica.