May in Your Orchid Collection
May Climate Data
- Average high: 87.2
- Average low: 72
- Average mean: 79.6
- Average rainfall: 5.52"
Excerpted from Florida Orchid Growing: Month by Month by Martin Motes. All rights reserved.
May is a month of transition in South Florida. Early in the month we can expect the driest weather of the year. Because of the clarity of the air and lack of cloud cover, temperatures rise rapidly in the late morning and can reach the upper eighties or nineties by mid afternoon before cooling substantially in late afternoon. Fortunately, over night radiant cooling rapidly dissipates the previous day’s heat. May mornings are a delight, the wise orchidist rises early to enjoy them and to finish his chores before the heat sets in. Chief of these should be extensive dragging of hoses.
May’s wide temperature swings and dry air suit our orchids to a tee. New growths on sympodial orchids are developing apace and by continuing the careful watering practices of April (i.e drenching them thoroughly with repeated applications of water to saturate their roots and potting media, then allowing them to dry to nearly ‘hard’ dry) we can launch them into the summer in vigorous, disease-free growth. Remember, this saturation can only be achieved with two or more soakings to the point of runoff spaced a few minutes apart. Merely holding the water on the plant extra long will not suffice. The water needs to slowly soak into the roots and media. Test the weight of a “benchmark” plant to be satisfied that it is sufficiently heavy to be totally soaked. The arid air of early May will quickly dry the foliage but the roots can draw on the deep reservoir of water that you have provided with this careful, complete watering.
With the increased heat and light of May we do not want to put our orchids on too lean a diet. Fertilize with up to 2 tsp. of 15-5-15 per gal of water every week or so. Alternating with Epsom salts and potassium nitrate at 1 tbs. each per gal. is still a best practice during May. Always substitute fertilizer for a watering and apply like the water in two doses to the point of saturation. Never follow the widely stated but antiquated advice to “water before fertilizing”. It’s a receipt for over watering without any basis in logic or science, Now is also a good time to apply a soluble trace or micro element fertilizer. Follow the dilution rates on the package as mixtures and strengths differ. You can apply this in conjunction with the Epsom salts/potassium nitrate but never with the 15-5-15, 20-20-20 or any other fertilizer containing phosphorus. In South Florida’s highly alkaline water the phosphorus interacts with the other metallic elements, reducing the effectiveness of the trace elements. Potassium nitrate, 13-0-46, is the perfect companion to minor elements because it not only lacks phosphorus which would hinder the absorption of the trace elements but the nitrate nitrogen seems to enhance their uptake.
May is still prime time for re-potting. With cattleyas, dendrobiums and other sympodials, the virtuous among us have long since finished this labor of love, but the majority of us are faced with the moral dilemma of doing the potting now or waiting until next year with the pseudo bulbs of our plants overhanging their pots and proclaiming to the world our sloth. The one instance in which this dilemma must be resolved absolutely in favor of the plant, is when the media has broken down in the pot. This condition will encourage root rot to become stem rot which will pursue the rhizome even into those over arching bulbs. If in doubt, give the media the “nose test”. A pinch of media taken from below the surface of the pot should smell “sweet”. A sour smell or the odor of a pond bottom indicates media that is broken down and must be replaced as soon as possible.
The case in which this is almost universally true is with plants potted in sphagnum moss. Sphagnum simply will not last beyond one year (even under cover) in South Florida. As the vast majority of commercially produced Phalaenopsis are now grown in sphagnum, recently acquired plants MUST be re-potted annually. As most Phals. will be finishing their flowers, now is a good time to get them right for the new year’s growth. When repotting, one can, of course, choose a more durable media; rock, red wood chips or various mixtures and avoid this annual ritual. Choosing a more durable media will entail modifying one’s watering schedule to accommodate the faster draining, quicker drying qualities of these harder substances.
May is a great month for re-setting vandaceous orchids whose baskets have deteriorated or that have grown too tall to be easily managed. keikies (off-shoots) can be most safely removed now. In both cases choose the most durable containers for the plants so they need not be disturbed for years. Teak or other hard wood baskets and clay pots last longest. Above all make amply sure that the plants are firmly fixed in their lodging. Vandaceous orchids, above all others, are intolerant of being loosely set. The very height of these plants act as a lever to keep them rocking unless we anchor them securely until their new roots affix themselves to the new containers. Stake and tie them securely until their abundant roots take over. Unsightly staking can then be removed.
As we bask, lulled into complacency by the nearly ideal weather of early May, Summer sometimes surprises us. Toward the middle or end of May, the weather in South Florida literally undergoes a sea change. The large continental weather patterns which have dominated our weather through the winter and early Spring give way to the tropics and the prevailing south easterly trade winds return us to the interaction of Gulf Stream and peninsular with its characteristic afternoon thunder showers. Although lacking the clockwork consistency of June, the rains have come and we must be prepared for them.
The relentless and increasing crescendo of rain will, by summer’s end, tip the balance in favor of the ubiquitous fungi lurking to attack our orchids. The time to scotch their plans is now; an ounce of prevention is worth a pound of cure.
Leaving the taxonomic niceties to the experts, fungi which attack orchids in Florida fall into two broad classes; the leaf spotting types (Cercospora and Phyllosticata) and the soft rots (Pythium and Phytophthora). Fortunately, for modern orchidists, excellent systemic fungicides exist for both types. While these chemicals are no substitute for good cultural practices, i.e. adequate spacing, brisk air movement; the strongest possible light combined with careful watering, fungicides provide the edge to approach near total control of most fungal diseases even in their ancestral home, South Florida. May is a good time to take stock of the collection and see which plants are overgrown and need more space or perhaps even re-potting. The increase in air circulation is well worth the effort. Trimming shade trees and moving plants to brighter locations are also good strategies for May. May is also a good time to consider a preventative spray program before disease has a chance to get the upper hand in our collections. An ounce of prevention begins now.
Leaf spotting fungi are symptomatic of poor air circulation and inadequate light but even under good growing conditions are rarely entirely absent from orchids in South Florida. This near inevitability results because the same diseases also afflict so many other tropical plants in our gardens. Under the battering of the heavy and sustained rains of our wet season, the most minor of problems can occasionally blossom quickly into a major epidemic. Thiophanate methyl (Cleary’s 3336, Domain, Fungo) is the proven and recommended systemic fungicide to control leaf spotting. It is even more effective when combined with Mancozeb (Manzate or Dithane M45.) Two pre-packaged combinations are available; (Duosan, and Tops MZ ). Always follow label recommendations for rate of application.
To be truly effective, Thiophanate methyl should be applied initially early in the growing season (IE now!), then again in two weeks and then every 5-6 weeks thereafter across the rainy season. Faithfully followed, this regimen will control nearly all leaf spotting fungus, including the dreaded ‘Thai crud’: Phyllostictina capitalense. A spreader sticker enhances the effectiveness of the fungicide by holding it on the plant through the hardest rain.
The soft black rot of sympodial orchids and crown rot in vandas are caused by two different organisms i.e Pythium and Phytophthora although in effect they are indistinguishable. Control of these diseases necessitates different chemicals from those used on the leaf spotting diseases. Etridiazole (Truban) has long been used. For the amateur it is readily available in combination with Thiophanate Methyl (the recommended chemical for leaf spotting) in the formulation Banrot. Applied in the same manner suggested above for Thiophanate methyl to control leaf spotting fungi, this pre-packaged combination should be adequate for most circumstances and control crown rot as well. If problems persist two other systemics give excellent control: Aliette (Fosetyl-aluminum) and Subdue 2E (metalaxyl).
All chemicals should only be applied at the rates and according to the label instructions. If in doubt about whether to or how to apply a pesticide always call your County Agricultural Agent at 305 248 3311 for advice.
April in Your Orchid Collection
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FEBRUARY IN YOUR ORCHID COLLECTION
FEBRUARY CLIMATE DATA
- Average high: 77.7
- Average low: 60.7
- Average mean: 69.1
- Average rainfall: 2.07"
Excerpted from Florida Orchid Growing: Month by Month by Martin Motes. All rights reserved.
Despite the bloom on the avocados and the burgeoning new leaves on the live oaks, February is not spring in South Florida. Danger of freeze continues past mid month and frost can occur still into March. Even if the weather is balmy it’s too early to let down our guard or take down any protection we have mounted against the cold. The trend however is toward the positive as each lengthening day brings extra hours of warming sunshine to begin waking our plants from their long winter’s rest.
February characteristically brings a wide swing of day to night temperatures, ideal for spiking ascocendas and vandas but also wringing from the air heavy dews and dense fog. Whilst these add a romantic atmosphere to the South Florida landscape, Wuthering Heights is singularly devoid of snails and slugs (much less Botrytis). The silvery carpet of dew provides a silky path to our orchids for snails and slugs which can range far, under these favorable conditions. They are eager to make a nice meal of your Phalaenopsis leaves or the soft crowns of your vandas before they retire during the dry months of March and April only to dream of the fresh shoots of the sympodial orchids brought forth by the first rains of May. Now is the time to give them a rude awakening. Remember that snail bait is most effectively applied lightly (scatter the pellets every few feet) and frequently (every 7 to 10 days). Two or three applications should do the job.
The heavy fog which can cause condensation on leaves even under cover can also bring trouble. Botrytis is a fungus disease that can disfigure flowers with small black spots. Particularly apparent and annoying on white Phalaenopsis, Botrytis can ruin other flowers as well. Control is typically achieved in commercial greenhouses with fungicide in aerosol forms and by running fans to prevent condensation on the flowers. The latter option is also available to collectors. A small fan turned on the spiking and opened flowers at night will greatly alleviate the pressure of Botrytis. So will, to a degree, the application of soap which we suggested in January to control mites. Bicarbonate of soda, ordinary baking soda, at 1Tbs. per gal will help as well. Quaternary ammonium compounds (Physan, RD40, Consan, pool algicide) also give some control. Maintaining long lasting flowers like Phalaenopsis, dendrobiums and bi-foliate cattleyas in more perfect condition is well worth the effort. Having waited so long for the flowers we want to enjoy them as long as possible and they do all last longer in cool weather.
The lower overall temperatures of February call for less frequent and lighter applications of fertilizer as was the practice in January. If any reddening of the foliage persists another application of Epsom salts (1Tbs per gal), preferably in combination with Potassium nitrate, is called for; Nitrate nitrogen being more available to the plants under cooler conditions. If your resolve holds steady not to water (or above all) fertilize those Himalayan dendrobiums, your reward may shortly become evident in bursting flower spikes.
Like the avocados and the live oaks, many cattleyas and other sympodial orchids have bloomed and are just commencing new growth in February. Right after flowering is usually an excellent time for repotting from the plant’s perspective and the cool day time temperatures in the greenhouse are hospitable to the orchid grower as well. It’s still a bit early to re-basket vandas But an early start on the cattleyas will allow plenty of time and energy for those Spring chores which are right around the corner. With that thought setting out to secure a good supply of pots in anticipation of the potting season ahead is on February’s agenda.
January in Your Orchid Collection
- Average high: 76.5
- Average low: 59.6
- Average mean: 68.1
- Average rainfall: 1.88"
Excerpted from Florida Orchid Growing: Month by Month by Martin Motes. All rights reserved.
January is somewhat like December but in reverse, with each succeeding day bringing longer hours of sunlight until days are long enough that afternoons return at the end of the month bringing extra sunshine to warm us after the extra sharp cold snaps. January, like December, is cold and dry, in fact even colder and drier. Dry is good, cold can be very bad. We need to accentuate the positive by especially careful watering in January. By keeping our plants as dry as possible and spacing our waterings as far apart as possible, we conserve our potential to use water to protect our plants from the cold, keeping our powder dry, as it were. In January water early, water thoroughly when you do and do so sparingly. The cooler overall temperatures of January are much less dehydrating even to plants which have received less water. remember, many of our orchids come from seasonally dry and cool climates not so different from South Florida. Many orchids are equipped to handle the drier cooler conditions of our January. A good strategy is to “top-up” the light watering that our plants receive with the passing showers that each successive cold front brings. This slight additional irrigation may prove to be all the watering that many genera need. Such parsimony, preserves the possibility of using water on truly cold nights to warm our plants.
Water is the only feasible source of heat available to plants grown in the open, under trees, in shade houses or on patios in South Florida. Ground water here (and in most of the rest of the world is about 63 F. (16C). Water out of municipal systems is not far different. On truly cold nights turning on the water can be of great benefit to our plants, provided that they have not been over-watered in the days and weeks preceding, thus inviting the ever present fungi to do more damage than the cold. For this reason as well, in general, orchids are better off dry until temperatures approach frost or freezing. The logic for maintaining plants dry is not only to minimize fungal problems but also because cold air is typically very dry air. If plants are wet in very dry and rapidly moving air say 10 or more MPH, evaporative cooling can take place, chilling our orchids further and faster than they would if dry. When the water goes on it needs to be in heavy volume and it needs to stay on to keep the plants thoroughly bathed in its warmth. Very still air on the other hand, presents a different danger as frost is possible at temperatures higher than is commonly realized. In calm air frost can form at higher elevations and settle in on plants while the surface temperature is only in the upper 30's. The best forecast for nights when the temperature will hover near 40 is a light wind of 2-5 miles per hour. This light wind mixes the warm air near the surface and draws warm from the earth. Clear, cloudless, still nights with bright shining stars elevate the spirit but harbingers frost.
Forecasts of temperatures below 40 F should stimulate us to action.
If it is not practical to bring all the Phalaenopsis, vandas and hard cane dendrobiums into the house or garage, think of using water to help protect them. Shade cloth or even patio screen hold in a surprising amount of heat like an lacy Mantilla. Under screen, a fine mist head attached to a hose and left running beneath the bench or plant rack will provide several degrees of additional warmth that will often sufficiently temper the chill and ward of any light frost settling in. Growers with swimming pools frequently turn on the recirculating pump to keep a supply of warm water near the pool’s surface where it can add heat to the ambient environment. A few degrees of warmth frequently makes all the difference to our sensitive orchids. In more open areas not protected by a permanent irrigation system, an oscillating sprinkler at the end of a garden hose is very effective. These are readily available at Home Depot and garden shops for a few dollars. On frosty nights, start the water at bedtime and let it run until the sun is up. The extra water once or twice in a month will do no harm to orchids that have been properly and judiciously watered the remainder of the month. In fact, these occasions present the opportunity to be sure that excess fertilizer salts have been leached from the pots and medium. A good work can be born of necessity!
Remember that Himalayan dendrobiums and ‘‘warm growing’’ Cymbidium hybrids will positively relish temperatures down to 32F and a light frost is just the ticket for great bloom. Keep the water off these!
In the drought of January, mites, which affect nearly all genera of orchids, continue to be a serious problem that will only get worse. They will reach a crescendo in March and April but January is a good time to scotch them. Paphiopedilum and other softy leaved genera are particularly susceptible but no genus is free of them. One theory on why deciduous genera such as Catasetum, Calanthe and others lose their leaves hypothesizes that this totally rids them of mites.
Being totally rid of mites is a good thing! Sometimes this is easier said than done because mites reproduce with such voluminous speed. Their life cycle from egg to reproductive adult being is as short as twelve days. In order to control mites one must achieve as total a kill of the population as possible. Total control can only be achieved with two successive sprays. After spraying for mites initially, one must spray again in 7 — 10 days. No single spray is totally effective in killing both adults and eggs and a second spraying is necessary to kill any survivors before they can reproduce. Oil as recommended in the December chapter at 1.5 oz per gal followed in7-10 days by soap at the rate of 2 oz per gallon is very effective. These treatments are also quite effective against scale and mealy bugs which thrive on drought as well. Be sure your plants are well watered the day before applying both oil and soap and be sure that you cover thoroughly all leaf surfaces especially the lower ones which are mites favorite hide outs.
For those who wish to be more aggressive, the University of Florida IFAS recommended chemicals for mite control are:
Avid 0.15 EC
Kelthane T/O
Mavarik Aquaflow
Talstar Flowable
Always follow label instructions for use. Any of the can be alternated with the soap or the oil in the 7-10 day cycle.
Controlling mites pays huge dividends! You’ll be surprised at the extra vigor your plants display.
Cold Watch
As cold is a major theme of this month, a review of some factors effecting temperatures in South Florida should be particularly valuable to new comers in the wide world of orchid growing.
While we bask in the warm glow of a tourist board’s vision of winter, (made all the warmer by thoughts of our envious friends and relatives stuck in the northern snow and ice) we should be mindful that January can produce quite severe cold. The majority of hard freezes in Florida take place in January, and even short of that catastrophe, the month usually brings the coldest weather of the year. We need to keep a sharp eye on the weather reports while remembering that in our almost island of Florida a number of factors influence the severity of the cold which will impact us.
First the shape of the cold front interacting with the shape of the peninsula. The weather that delights the tourist board and all of us while plunging most of the US into the throes of ice and snow usually result from particularly large, slow-moving masses of cold air that have spread across much of the continent before reaching Florida. Large broad masses of cold air that seep downward over a broad front also cover the Gulf of Mexico and the Atlantic as they progress southward. These tempering bodies of water bathe the cold to merely refreshingly brisk temperatures. More dangerous to our plants are the smaller, tighter, fast-moving fronts which plunge like a dagger of cold straight down the peninsula to the tropical heart of South Florida. Such fronts typically spawn the freezes and severe plant-damaging cold that is of the greatest concern to orchidists and other plant people. These Siberian Express fronts bring winds out of the Northwest that are un-influenced by the benign, protective bodies of water flanking the peninsula as they drive down the central landmass of Florida. When the winds from an approaching front start out from the southwest and move gradually to the northwest and then quickly to the north and northeast, we can expect cold nights and warm days that reasonably well-protected orchids not only tolerate but in some case actually relish. The more savage fast moving fronts where winds start in the Northwest and stay there are the ones to send us thinking of moving plants or providing additional heat.
Wind direction is always critical in South Florida. Because of the peninsula’s decided eastward cant, winds from the north in much of South Florida are in fact relatively mild. North winds here are blowing across the warm Gulf Stream. The first shift to the northeast absolutely spells relief as the warm Atlantic has absorbed the cold.
Wind speed is also important. Strong winds at low temperatures chill our plants more rapidly, exposing them to additional hours of chilling. “Wind chill factor” has no relevance to plants until the actual air temperature drops to a level unacceptable to the plant. After that, the more rapidly the plant itself’s temperature falls to that damaging level and the longer it stays there the worse the case. Wind speed enters the equation only if the final low temperature is below our plants’ tolerance. Wind breaks of vegetation or manmade are always to be sought. Native epiphytic orchids hide out in the most protected hammocks and sloughs. We can learn from them.
Dead, still air looms with another threat: radiational cooling which can allow frost generated at higher levels of the atmosphere to settle in on our plants even when the air at the surface is only in the upper 30's. These frosts typically occur when the front has passed leaving such low humidity that there is no moisture in the air to retain ground heat which radiates quickly into the cold reaches of space. Light winds of 2-5 miles an hour are our friends on these nights. They stir additional heat from the ground and keep the colder upper air from settling in.
Relative humidity also has a profound effect on temperatures. Dry, clear air allows heat to radiate out into space. Those bright starry nights are beautiful but as Good King Wenceslas knew they are not necessarily our comforters. The best measure of the dryness of the air relative to cold is the dew point. When water vapor is wrung from the air an incredible amount of energy is released and the heat of transformation raises the air temperature a degree or two. Because of this phenomenon, the dew point is usually the closest measure of the coldest temperature that will be reached in the night. Particularly on still clear nights it should be monitored closely.
Wind direction, wind speed, dew point — where does one find these on a chilly night? At the Florida Agricultural Weather Network (FAWN), a system of automated weather monitoring stations, as close as your computer. There will be a station near you. There are also several at points north of the nearest location that give data on conditions that are effecting areas through which the cold front is moving toward us. FAWN is updated every 15 minutes at http://fawn.ifas.ufl.edu. Bookmark it for something other than worrying to do on those cold nights.