- Average high: 81.2
- Average low: 67.5
- Average mean: 74.4
- Average rainfall: 3.43"
Excerpted from Florida Orchid Growing: Month by Month by Martin Motes. All rights reserved.
In November we can no longer afford to be dominated by the illusion, so easy here at the northern edge of the tropics, that summer will never end. Although Indian Summer persists for the whole winter in South Florida, November is the month to prepare our plants for those short sharp blasts of cold which are inevitably coming as each successive cold front pushes the overall temperature a little lower and a little lower. Each day is shorter too. The loss of daylight savings time should awake us to the fact that there are less hours of sunlight to save our plants from the chill of the night. Many genera are already anticipating this sea change and have completed their growths for the season. Some like Catasetum, Cycnoches, Calanthe and the nobile dendrobiums are even beginning to shed their foliage in preparation for the cool, dry season. While the Himalayan Dendrobium species of the nobile and Callista types, calanthes, cymbidiums and an few others, actually relish temperatures down to near freezing, and most cattleyas and Oncidium alliance species and hybrids are not bothered by temperatures in the mid-thirties, the majority of the genera which we grow, vandas, evergreen dendrobiums, Phalaenopsis and others, benefit from being protected from the cold. Now, while the first breathes of cool air remind us that more and stronger cold is in the offing, is the time to start thinking about protecting our plants.
In nature nearly all the tender tropical epiphytic orchids native to South Florida are found nestled in the bosom of deep hammocks where they are well protected from the wind. This observation leads us to think of protecting our orchids from the north and northwest winds. Creating or utilizing already existing wind breaks to the north and west of our orchids will limit the ability of the wind to steal the warmth out of our plants. The critical factor is not the low temperature that the air reaches but rather the temperature to which the plant tissue is chilled and for how long. This is why limiting the movement of cold air over our plants is essential. In still air, plant tissue (mostly water but with some dissolved salts) retains heat for a long time and is aided by the plants’ metabolism. The very goings on of life generate heat, therefor considerable exposure to still air is needed to chill a plant to the temperature of the surrounding environment. Not so if wind enters the picture. Wind can quickly rob the plant’s surfaces of heat, chilling the plants tissue deeper and deeper. When the plant’s temperature tolerance is reached, at best growth ceases or worse yet damage ensues. Slowing the cooling process and limiting the hours of exposure to sub-optimal temperature is the best gift we can give our plants for the holidays.
Protecting our tender plants from exposure to wind must be our primary concern in preparing them for winter. Buildings, walls and even thick hedges can be very effective windbreaks slowing or stopping chill air. Choose places in your garden that offer this sort of protection to your orchid plants wherever possible. The geography of Florida plays into the equation as well. Because the Florida peninsular juts decidedly to the Southeast (Naples is due south of Jacksonville), protection from the Northwest wind is even more crucial than protection from the North wind on the east coast of Florida. Northwest winds are blowing out of the cold heart of the landmass while true North winds have in most locales usually blown over more warm water and less cold land. Regardless of the degree of north, safeguarding our collections from the wind is critical to their healthy maintenance. Not until the air circulating clockwise around the cold high pressure system shifts to the Northeast to blow over the warm Gulfstream can we relax our guard.
Orchids that are grown in shade houses, in patios or pool enclosures can be protected by installing plastic film on the north and west walls of the structure. This can be attached with staples or other devices that allow the plastic to be furled in warm weather and only lowered for those few nights when it is needed. Easiest to come by (Home Depot, or any hardware store) and cheapest, is 6mil clear polyethylene (don’t use 4mil; it rarely lasts the winter being exposed to Florida’s bright ultraviolet light). One hundred feet by ten costs about $20. Stored in a dark place, this stock will last the average grower several years and be a very small investment that will yield greatly improved orchids. Handled with care in furling and unfurling, 6 mil plastic usually will get the grower through the winter. If unobtrusive, it may be simply left in place till March. White polypropylene, similar to nursery ground cloth, is used by many nurseries for winterizing. More expensive than polyethylene, it is very durable and will last many more years. Some growers have it cut to size, taped and grommeted for easy up and down installation and storing. Universal Supply (1-800-432-3009) has it. Given the dimensions and enough lead time they can customize it for you.
Getting our growing area ready for winter is one half of the equation. We must also get the plants themselves ready. Healthy, well-nourished plants withstand cold better as do plants that are harder and not too lushly in growth. Because both light and temperature are lower in November and most orchids have slowed their growth, they need less fertilizer. In cooler weather ammoniacal nitrogen is less available to our plants because it needs the assistance of bacterial action to ease its absorption by the plants. Nitrate nitrogen is more desirable therefore in cooler weather, because it is more quickly and readily absorbed by the orchids. Check the label on your fertilizer and try to choose one with a higher ration of nitrate nitrogen to ammoniacal nitrogen for winter use. The very best source for nitrate nitrogen is potassium nitrate (KNO3). It has the formula 13-0-44. The lower level of the desirable nitrate form of nitrogen is well suited to the continuing but diminished nutritional needs of our orchids in cool weather. The level of potassium is thought to contribute to the ‘hardening’ of the plants. Try to obtain the soluble or ‘Spray’ grade. If only Prills (small beads like tapioca) are available they will need to be dissolved with boiling water, a tedious task.
Potassium nitrate is superlative also because it contains no phosphorus which, in combination with our hard, alkaline water interferes with the plants’ absorption of trace elements. Trace element nutrition is especially important to maintain healthy orchids in cool weather: above all, magnesium, the ‘major’ minor element. The reddening of orchid foliage which is usually attributed to cold is in fact the symptom of magnesium and potassium deficiency. Cold is only the efficient cause of this reddening; the material cause is lack of magnesium. Epsom salts at 1tbs. per gal plus potassium nitrate at the same rate will quickly bring back the green. This regimen can be alternated with a general trace element mixture (follow the package rate) plus potassium nitrate. Indeed, following the recommendations of the Michigan State University study published in the July 2003 issue of Orchids, symptoms of magnesium or potassium deficiency might be a warning that we should have been following something closer to this “winter” fertilizer regimen all year. We now recommend alternating applications of 1TBS each of Epsom salts and potassium nitrate with a balance fertilizer such as 20-20-20 or 18-18-18 year round not just in the Fall. Best of all is a 15-5-15 with additional calcium and magnesium. peters markets one as Excel.
The Epsom salts are as near as your medicine cabinet. The potassium nitrate is more difficult to find but a trip to the nearest Farm supply store is worth the effort. You’ll save a bundle on fertilizer and have plenty of potassium nitrate left over to grow the biggest bunch of bananas in the neighborhood.
If you have the energy, November is also a great time for starting to pot those sympodial orchids (cattleyas, oncidiums, et al) that have finished blooming. You’ll have a leg up on the Spring potting and will glow with virtue in expectation of the rewards of the Holidays. Be especially careful at this season that the newly transplanted orchids are well secured in their containers. It may be many weeks till they have broken growth and can anchor themselves with their own roots. If the plants are allowed any wiggle room the newly emerging roots will be chaffed off, sending the plant into a slow and difficult to reverse decline.
- Average high: 85.4
- Average low: 72.2
- Average mean: 78.8
- Average rainfall: 6.19"
Excerpted from Florida Orchid Growing: Month by Month by Martin Motes. All rights reserved.
October is a month of change in South Florida. If the Romans had lived here where we do, they would have named this month for their two faced god Janus. Usually around the middle of the month, and certainly by the end of the month, the first strong cold front pushes into South Florida bringing to a close the monolithic heat and damp of summer and ushering in weather as most of the continent knows it, alternating periods of warmer and cooler. Although warm temperatures will persist for another month or so until the technical end of the hurricane season, the tropics are in retreat and the temperate zone in the ascendancy. Each successive cold front foreshadowed by ever lessening rain storms will progressively cool our temperatures and dry our air. But days are shortening too, providing less hours of sunlight to heat the air and slowing the drying process. Nights are longer and cooler which produces the same effect, slower drying. Now we must start to move into the consciousness of winter and take greater care to insure that our plants are thoroughly dry before we water them again. The shorter days of October dictate that we rise even earlier to water if necessary. Each extra hour of daylight is to be cherished by us as well as our plants.
Most of our orchids are well aware of this sea change. The shortening days of late summer have told many genera to finish their growth and prepare to rest. We need to listen too. And look! The last smallest leaves of these highly seasonal plants will have unfolded at the tips of their new growths telling us that their growth cycle is finished for this year. Himalayan dendrobiums of the nobile type and of the section Callista (D. aggregatum et al.) now begin their five months of carefree existence in South Florida. They should be put in a bright spot and given no more water and above all, no more fertilizer until after they have bloomed in Spring. Catasetums, mormodes, Cycnoches, calanthes and other deciduous types should be treated the same way. Whatever moisture nature provides in the increasingly heavy dew and the passing rains that usher in most cold fronts will be adequate for these plants whose native environment is a seasonally monsoon one like ours. Benign neglect suits these genera just fine and what a relief to the conscience of the ever busy orchidist! The truly devoted will group these genera together, preferably at the edge of the growing area and high up where they will receive the maximum of light and air circulation. Grouped thus, the chance of an accidental watering of these while taking care of the more thirsty genera is minimized. Another strategy is to tip the pots of these dormant genera on their sides thus eliminating much natural rainfall and avoiding a misdirected hose spray. Some growers even remove plants that have finished both growing and flowering from their pots entirely. When new growth begins in the Spring they will receive a fresh start in new medium.
Many cattleyas, laelias, oncidiums and phalaenopsis-type dendrobiums will be finishing their growths and should be hardened off with reduced water and fertilizer but not the Spartan regime of the deciduous type. Lower nitrogen fertilizer applied at a lower rate and with less frequency will make these genera happy and prevent them from breaking into unwanted off-season growth that frequently hampers flowering as well. Many growers tend to use higher phosphorus, lower nitrogen fertilizers of the “Bloom Booster” type during the cooler weather. But less frequent applications of the recommended 15-5-15 is a better strategy. These applications should be spaced further apart as well, at ten to twelve day intervals. Less frequent watering will also do for these genera. When the frontal rains pass through, check to see that the pots are thoroughly wet by giving them the “heft” test and if they are not heavy enough “top them up.” Let them dry ‘hard’ before watering again. In cool weather especially, less is more.
Monopodial orchids like Vanda and Phalaenopsis which want to grow continuously, feel the change too. The broad swing of day to night temperature stimulates flower spike initiation in these genera. You can spur them on to greater excitement by giving them a shot of high Phosphorus ‘Bloom Booster’ fertilizer just before or just after the sudden drop in night temperatures precipitated by the passing of a cold front. For most of the year “Bloom Booster” fertilizer appears to be in fact “Bloom Blocker” but (perhaps from faith rather than science) high phosphorus seems to have the desired effect (perhaps from shock) when the first cold snaps are also halting vegetative growth. We like Miller’s Solugro (12-48-8) because it contains none of the ugly blue flower, clothes and hand staining dye. Other brands (with or without dye) are equally effective. Look for a very high middle number and a relatively low first number or ask at your garden center for a ‘starter solution’ which is the moniker for these fertilizers when used in planting out vegetable or annual seedlings. Because the nitrogen level is lower, you can use a full tablespoon of these or more, per gallon.
Cooler weather calls our attention to our plants’ needs for trace elements. Chief among these is magnesium, often described as the ‘major’ minor element. Magnesium deficiency shows up in orchids as a reddening of the foliage particularly when the plant is stressed. This color change is frequently attributed to cold as it occurs following spells of cooler weather. This observation is the fallacy of post hoc, ergo propter hoc; cold is merely the efficient cause: the material cause is lack of magnesium. Hopefully the new fertilizer regimen outlined in the July chapter will minimize or eliminate the reddening by keeping the magnesium level up in the plants. But... Epsom salts (MgS) is the best and most readily available source of magnesium. This can be applied with Potassium Nitrate (KNO4) at the rate of one tablespoon each per gallon. Potassium Nitrate has the formula 14-0-44. The missing number in the middle is Phosphorus. In combination with our highly alkaline water phosphorus tends to react with magnesium and the other metals of the trace element group. Never apply magnesium and the other trace elements in combination with fertilizers containing phosphorus. A general purpose trace element mixture can be added to the mix of magnesium sulfate and potassium nitrate at the rate recommended on the label.. (Concentrations vary). Goodbye red, Hello green!
Excerpted from Florida Orchid Growing: Month by Month page 126-127 by Martin Motes. All rights reserved.
It's an ill wind that blows no one any good. Minor hurricanes are still a major nuisance but small blessing can nonetheless flow to South Florida orchidists in the enforced pruning of our trees which will bring cherished light to our orchids. The prunings themselves are a major resource for the clever orchidists. The streets of South Florida are typically lined with a virtually inexhaustible lode of great orchid mounting material in the wake of minor hurricanes. All that is needed is the energy to cut and haul the appropriate branches that will supply years of great orchid mounts. With such an abundant (dare I say windfall?) one can even be quite picky. The savant orchidist should select his material with an eye to the best suited and the most appealing. Three species stand out. First, the golden trumpet (Tabebuia argentea or caribae) whose cork like bark is ideal for most orchid genera is always the first to fall and particularly abundant in roadside plantings.
Live oak (Quercus virginiana),a favorite host of our native epiphytes, is also highly favored by epiphytic orchids in general and dendrobiums in particular. It is, of course, of the very same genus as cork itself and the wood is highly durable.
Next among the commonly fallen and desirable is button wood (Conocarpus erecta) both green and silver, again a favored host of native epiphytes. These branches is "driftwood" on the hoof. It is the roots of this species that become the "driftwood" of orchid culture. The branches are great mounts too.
Other species such as bottle brush (Callistemon) are good but the three common storm victims will provide more than enough of the very best mounts. Look for branches that are forked or twisted or that have other distinctive turns that will add character to the finished mounts.
Try to imagine the plant situated on the branch. A small chain saw makes short work of these branches, quickly rendering them into raw works of art. A well sharpened double set hand pruning saw will do fine. Now would be a good time to acquire these tools if needed before they are inevitable truly needed in the aftermath of a major hurricane. When a "minor" storm has passed, we can count our blessings and collect the orchid manna falling from heaven.