A Few Words on Dealing with Winter Weather

Judging from some of the recent news headlines, one might get the impression that southern Florida is setting records for cold weather. Nothing could be further from the truth. The winter of 2009-2010 was the coldest since 1940, and there was another cold outbreak in December 2010, but since then we have had unusually warm winter seasons.

Reaction to cold nights around the middle of December 2017 and again during the first week of the new year has been a little bit frantic in some quarters, but the truth is that we simply have become spoiled by our abnormally warm recent winters. Low temperatures in southern Florida this winter have come nowhere near record readings. Nevertheless, there has already been enough cold weather in 2017-2018 to cause damage to tropical plants, and additional cold weather is likely to invade our area from time to time over the next couple of months. Accordingly, the staff at Richard Lyons’ Nursery wishes to address the subject of dealing with the effects of cold weather on our tropical plants.

In deciding what to do to protect plants from cold weather, you should first become acquainted with the cold-hardiness of each of your species. If you didn’t ask the seller at the time you bought the plant, then talk to neighbors or friends who have grown the species that you have. That approach avails you of people’s experience locally. But you can also supplement their input by way of an Internet search for the plant name along with a term such as ‘cold-hardiness.’ The steps you take to learn the cold tolerance of each of your species will allow you to rank the relative sensitivity of your plants and help you avoid wasting time on those that don’t need special care.

Next, pay attention to the details of the forecast. Frost can cause the fluids within plant cells to expand and rupture cell walls. A breezy night can be protective, because it prevents the formation of frost on leaf surfaces. However, at some level of intensity, winds can themselves cause damage; accompanied by low humidity, they can desiccate leaves. On the other hand, if winds are expected to be calm, it is possible for frost to form at a temperature above 32 degrees, particularly if the humidity is high. (Following passage of the cold front in mid-December 2017, even though lows in urban areas were in the 40s, temperatures in parts of the farming area dropped to 36 degrees, with frost.) It is not uncommon even on a breezy night for winds to cease right before dawn, and that can be devastating, because just a few minutes of calm can allow the formation of damaging frost.

On the rare nights when a freeze is expected in our region, the duration of temperatures under 32 degrees become important for the well-being of those plants which have enough hardiness to tolerate some frost. Consider citrus, for example. The trees themselves can handle considerable cold, but their fruit is less hardy. Cold can be both beneficial and detrimental to fruit. A certain amount of chill will cause it to sweeten, but if subfreezing temperatures persist for more than six hours, fruit cells begin to sustain damage.

Once you know the relative cold-hardiness of the plants in your possession, you can take steps to prevent, or at least minimize, damage. Obviously, you will have more choices at your disposal if you are dealing with containerized plants, at least those small enough to be moved. An easy and effective tactic is to relocate them beneath the cover of a large, dense-canopied tree. The tree’s crown keeps heat that is stored in the soil from radiating away as quickly as it would from open locations. Just a few degrees’ worth of extra warmth may be enough to protect your plant. If your containerized plants are too heavy to move, you may nevertheless possess a slight advantage if they are on higher ground on your property, since cold air drains to the lowest spots as it invades an area. In pancake-flat southern Florida, ‘higher ground’ is a fairly subtle concept, so even if you have placed your large containers in sites that are only a foot or two above the surrounding soil, that can help them escape the worst damage.

You may also put a cover over a plant, but be aware of the limitations. A cloth cover can help a bit, but it permits heat loss through the fabric. A plastic cover can be more effective, but you must avoid allowing it to come into contact with plant surfaces, since the plastic will act as a conductor of cold into the plant. If sub-freezing temperatures are predicted and your containerized plants are too numerous to move, you can employ the technique used by vegetable farmers: Icing. A layer of ice applied by a sprinkler can protect plant surfaces from the worst effects of cold. However, if you opt to go that route, you must be sure not to turn off the water too early. The best policy is to continue watering until the sun is high enough in the sky to melt the ice from plant surfaces.

Finally, you should give some consideration to what remedies to undertake following a damaging cold event. In most instances, the best approach is to assess the damage, but do nothing initially. In particular, don’t prune dead leaves from shrubs or trees; they tend to insulate the plant from further problems in any subsequent cold weather outbreaks, Wait until the chance of frost for the season is safely past. By that time, the plant may generate new growth that provides you the perfect natural indicator of where to prune away dead material.

Even if your plant exhibits no outward signs of cold damage, don’t assume that it came through unscathed. Palms in particular may look fine even though they have suffered internal damage to the bud that may lead to the plant’s death months later. To be on the safe side if you own a species known to be cold-sensitive, pour or spray a fungicide (diluted according to label instructions) directly into the bud at the spot where new leaves emerge, and administer a second dose 7-10 days later. Alternatively, you may apply 3% hydrogen peroxide, the strength found in drugstore formulations, into the bud. But avoid the temptation to treat your palm with both types of chemicals; they are not compatible.

Maintain standard watering habits. While periods of rainy weather may relieve you of the need to provide supplemental water, you should stay alert for the sudden onset of dry weather that requires intervention on your part.

Tropical Bonsai

When you hear the word ‘Bonsai’, you usually think of temperate zone conifers, Japanese maples, and other assorted deciduous trees.  However, in South Florida, ‘Bonsai’ takes on a whole new connotation.  The choices for plant material are almost endless.  There are our natives to choose from, such as the Stoppers, Lignum-vitae, or Christmasberry to name a few.  Then there are tropical fruit trees, like Jaboticaba, Barbados Cherry, and Cherry of the Rio Grande.  Oh yes, the biggest category of all, the ornamentals with such standbys as Bougainvillea, Ficus neriifolia, and Tropical Dwarf Holly (Malpighia coccigera).  Of course, we too have our conifers, although most of them are of a tropical nature, bonsai enthusiasts have grown them into nice specimens for years.

If you are an experienced grower, or just want to get started, Richard Lyons’ Nursery has plenty of the plant material available to get you started.

Palms for Autumn Planting, Part V

The survey of palm species available at Richard Lyons’ Nursery in 3-gal. containers concludes this week:

Dictyosperma album var. album is commonly known as the Princess or Hurricance Palm. It is a pinnate, self-cleaning palm that features a yard-tall, waxy crownshaft. Endemic to the Mascarene Islands in the Indian Ocean, it is reported to be nearly extinct in the wild due to farming activities. In southern Florida, this water-loving species matures to about 30 ft. and performs best in a sunny site. It is more capable of tolerating a cold night followed by a rapid warmup than sustained periods of cool weather.

Licuala grandis, the Ruffled Fan Palm, is native to Vanuatu and the Solomon Islands. It is a striking small species featuring nearly circular leaves that look as if they’ve been cut out by pinking shears. Best grown in shade when young, L. grandis tolerates more sun later. Given generous irrigation, it will reach 15 ft. slowly in southern Florida. Because it does not have an aggressive root system, it can be maintained successfully in a container, particularly if a saucer is placed underneath it to hold water.

Syagrus botryophora, known as the Pati Queen Palm, is a fast-growing species endemic to the coastal woodland of Brazil. It has a thinner trunk than the standard Queen Palm (Syagus romanzoffiana). Its crown contains graceful recurved leaves with ascending, or V-shaped, leaflets. Rainfall in its native range is even throughout the year, so irrigation during the southern Florida dry season is a must. It matures to somewhere in the 20-50 ft. range, and responds well to nutrition that includes minor elements. Plant in full sun.

Thrinax radiata, the Florida Thatch Palm, is native from southern Florida into the Bahamas, the Caribbean, the Yucatan Peninsula, and Central America. Its palmate leaves are dark green on top, light green beneath. Pea-sized fruits ripen from green to white. Inground plantings mature to 30 ft. after many years. It is also recommended for both small yards and container culture. T. radiata is best grown in full sun to light or high shade. It is tolerant of winds, salt, drought and poor soils.

The series concludes with some recommendations on planting these palms in the ground, advice reinforced by our recent hurricane experience: Do not skimp on preparing a planting hole. Particularly in areas where limestone is near the surface, dig a large hole so that root system growth over the years will not be inhibited by the rock. However, it is better to refill the excavated hole with the broken pieces of limestone than to introduce a richer planting medium. The material within the planting hole should not be better than the surrounding soil, even if it is not highly nutritional. Nutrition can be provided through sound fertilizing and mulching practices.

Palms for Autumn Planting, Part IV

The survey of palm species available at Richard Lyons’ Nursery in 3-gal. containers continues this week:

Sabal mauritiiformis is probably the fastest-growing of the 20 or so species of Sabal. Native from northern South America to southern Mexico, this palm produces fairly large, deeply-split circular leaves — reminiscent of those of Licuala — even before the trunk develops. And the undersides of the leaves are mildly silvery. Eventually this palm will reach 30-60 ft. tall, with a trunk about a foot in diameter.

Satakentia liukiuensis is a palm endemic to the rainy southern Ryukyu Islands of Japan. A self-cleaning species, it possesses a beautiful maroon-brown crownshaft. It has a slow to moderate growth rate, maturing to about 30 ft. in our region, and is amenable to both limestone and sandy soils. S. liukiuensis holds up well to tropical storm conditions and can tolerate at least light frost. To see a nice stand of this striking palm, drive by the Lennar Foundation Medical Center on the eastern border of the University of Miami.

Serenoa repens is the Saw Palmetto, whose seeds are the source of an extract recommended in alternative medicine circles as beneficial to prostate health. A Florida native, it is a small, slow-growing species whose mildly fragrant flowers are a rarity in the palm world. Stems of this clustering species commonly ‘crawl’ along the ground and, over time, can extend several feet from the center of the plant.

Syagrus cearensis is a midsize, clumping species bearing slightly plumose leaflets unevenly distributed along the petiole. It almost always produces two stems, but occasionally sends up more. It was not described botanically until 2004. It is endemic to the northeast Brazilian states of Piauí, Rio Grande do Norte, Paraíba, Pernambuco, and Ceará, the last of which is the source of its species name. S. cearensis prefers a sunny position with good drainage.

Syagrus kellyana, endemic to Minas Gerais state in Brazil, is relatively new to Florida. It grows at a deliberate rate, reaching 6-16 ft. at maturity. S. kellyana bears a crown of dark green, gracefully-recurving leaves, and produces fairly large fruits. It appears to be rather cold-hardy. Native to granitic outcroppings or areas of thin soil, this species does not appear to mind the poor soils of southern Florida. For best results, plant S.kellyana in full sun on a site with good drainage.

Palms for Autumn Planting, Part III

The survey of palm species available at Richard Lyons’ Nursery in 3-gal. containers continues this week:

Cocos nucifera ‘Red Spicata Dwarf’ is a distinctive variety of the Coconut Palm. It bears vibrantly-colored (orange, not truly red) seednuts on spiky infructescences. The contrast between Dwarf and Tall Coconut Palms is manifested in at least two ways that are more predictive than height: Dwarf varieties have narrower trunks, and they begin to flower and fruit earlier. For best results with a ‘Red Spicata,’ fertilize generously during the growing season. Like all coconuts, this variety prefers to be grown in full sun.

Copernicia berteroana is perhaps the fastest-growing of the Copernicias, though it slows greatly in Mediterranean climates. Native to open, dry forests of Hispaniola, it reaches 20-33 ft. at maturity. It produces a dense crown of generously-segmented, bright green palmate leaves. The species is not particular about soil, so long as it is well-drained. Though its occurrence in the wild has diminished, it is reported to be widely used as an ornamental plant along streets and in parks in its native land.

Copernicia macroglossa, the Cuban Petticoat Palm, is noted for the skirt of old leaves that persists around its trunk for many years. Hidden under the ‘petticoat’ is a stem just 8 in. or so in diameter. The palm’s distinctive look is owed to its very short leafstems, which cause its large leaves to appear as if they emanate directly from the trunk. Like many species in its genus, C. macroglossa accommodates copious amounts of water very well, but also handles drought easily once established. It reaches 20-25 ft. in southern Florida.

Livistona nitida is native to central Queensland, Australia, where it is generally found near abundant sources of water, such as in the Carnarvon Gorge. Though capable of reaching over 100 ft. in its homeland, L. nitida tops out at about 40 ft. in our region. It features an open crown of numerous palmate leaves with drooping leaf segments. Its petioles are lined with curved, dark red spines. Still relatively uncommon in Florida, it can handle temperatures in the low 20s. Plant it in a sunny location.

Pseudophoenix vinifera is another palm native to dry areas of Hispaniola. Its species name is derived from its use, especially years ago, to make a wine. Its most striking feature is its swollen trunk, ringed by very pronounced leaf scars and coated with a whitish wax. P. vinifera produces abundant, showy scarlet fruit. It should be planted in sunny sites with good drainage. Once established, it is drought-tolerant. A slow grower, it may reach 65 ft. in its native region, but is more likely to mature to around 25 ft. in southern Florida.