Motes Orchids 9/6/19 Motes Orchids 9/6/19

September in Your Orchid Collection

Average high: 89.0
Average low: 75.7
Average mean: 82.4
Average rainfall: 8.38"

September looms as the only truly dismal month in South Florida. Even without the prospect of the unspeakable ‘H’ word, September disheartens since it is easily the dampest, dullest month in the year. Although more inches of rain fall in June, more hours of rain occur in the often slow, seemingly endless drizzles of September. Frequently a day or two can pass without so much as a solid hour of truly bright sunshine to lift our spirits and dry out our plants. Days are growing much shorter also, with long nights when our plants are wet from the frequent rains. Coming at the end of the rainy season when disease pressure has been building, September presents the maximum opportunity for fungal and bacterial diseases to take hold of our orchids. Hopefully careful watering practices and the judicial use of fungicides (as recommended last month) will have diminished the potential for disease in our collections. But even in the best managed collection, September calls for extra vigilance. Keep a close eye out for problems and remove immediately any plant that shows the first sign of fungus to a dry location to prevent the disease being spread by splashing rain drops. Good hygiene is particularly important this month. Clean up growing areas and remove any dead leaves, twigs or other organic debris from the plants and the ground. In September numerous diseases that linger in decaying plant material find the ideal conditions that allow them to jump to the living tissue of our prize orchids. Such problems can develop more quickly in September than in any other month. September is a month to stay home and be there for your orchids. Look at every plant, every day.

September, above all, is the month that the old Florida growers’ adage that "One needs a cat to grow good orchids," holds true. By leaving enough space between plants on a shade house bench for a cat to walk around without knocking them down, one provides the good air circulation which is absolutely essential in periods of protracted wet weather. Well spaced plants are much less likely to encounter disease problems this month. Remember that your plants will have grown considerably over the summer and that the space they occupied comfortably in the Spring has now been filled by their own growth as well as their neighbors. Space them out. Now is perhaps the time to decide to hang some of the larger ones where they will dry much more quickly. The small cute ones left behind on the bench will be very appreciative of the extra air and light.

Another excellent way to increase air circulation and enhance rapid drying is by trimming excess (particularly vertical) branches from all trees which support orchids or are near to orchid growing areas. By increasing the light and air flow one will also garner the benefit of reducing the possibility that such trees will be knocked down in a severe storm. Trees trimmed to permit proper air circulation and light for orchids were frequently the only ones which survived upright after Andrew. As there is rarely time to do such pruning when storm warnings are actually posted and creating extra debris is not then wise, now is the time to protect both your orchids and your trees. Days are shortening quickly now and more hours of rain and overcast skies mean that your orchids will benefit from all the additional light that they can get. Beginning the process of “hardening off” our plants by allowing more light to reach them will give them a leg up on the coming cool weather as well.

As orchids grown outside are so frequently wet in September, it is often difficult to apply fertilizer or fungicides to the plants because they are already damp. Catch 22! — the plants need extra protection because they are wet and because they are wet one can’t apply chemicals to protect them. In these circumstances, many growers find Quaternary ammonium compounds useful. Sold as Physan, Consan, Greenshield or Triathalon these disinfectants dissolve totally in water and can be applied to wet plants. Strengths vary so follow the label. Although Federal regulations say they should not, many growers substitute the cheap and readily available pool algicide which contain the same active ingredient. Home Depot sells a brand called ‘‘Pool Time’’ which could be purchased legally to disinfect walks and pathways at the rate of 1 to 2 tsps. per gallon and would certainly do no harm at that rate, if it came into contact with the orchids no more frequently than every 7-10 days.

This month when those brief periods of dry weather permit growers to think of applying other pesticides, they are tempted to think of giving their starving charges fertilizer as well. This is generally not a good idea with any fertilizer containing phosphorous (the second in the numerical series of three numbers). Phosphorus changes the PH of water and tends to interact with many other chemicals reducing their effectiveness. In September we need as much fire power from our chemical arsenal as we can get. A much better strategy in general to add some nutrients employs potassium nitrate (KNO3) 13-0-43 at a rate of 1 tbs per gallon of water. One should ask for the type usually referred to as ‘‘spray grade’’. In general sympodial orchids are reaching the end of their growth cycle as September progresses so a reduction in nitrogen from the potassium nitrate substitution or a missed fertilizer application usually does little harm to orchids grown outside in South Florida. Soft cane dendrobiums of the “Nobile” types will actually benefit from the reduction in feeding. It’s time to wean these deciduous types before cutting them off entirely from the grub next month. Vandas and Phalaenopsis on the other hand can be fertilized as often as weather permits and will bloom all the stronger for this extra attention in the coming months.

Snails can also be a problem again in September. Even if you earlier used the ‘‘lightly, frequently’’ baiting suggested in July, snails can travel long distances on wet ground in the dull, dark weather of September. Chances are your neighbors have not been as good as you on snail control. So, once more with feeling: snail bait "lightly, frequently" to give a warm welcome to any recently arrived mollusks. With an eye to the heavens (or at least to the TV screen), removing any old boards, empty pots or other debris that might fly about in a storm will also render the humble snails homeless. An opportunity to re-double your virtue and save some precious moments in the face of the storm that we hope never comes!

Motes Orchids 7/4/19 Motes Orchids 7/4/19

July in Your Orchid Collection

July Climate Data

Average high: 90.9
Average low: 76.5
Average mean: 83.7
Average rainfall: 5.79"

Although it mostly passes unnoticed to millions locked in their air-conditioned bubbles, July in South Florida is quite different from June. While the pattern of afternoon showers built from the moisture of the morning’s sea breeze persists in July, the thunder-storms are sharper and shorter. The clouds linger less and the foliage dries more quickly. Less quantity of rain falls in July than in June and periods of several days typically pass without a drop. This is good news for orchid growers. July (and August) allow orchidists to focus on the first essential of orchid growing, drying the plant out.

Frequently, neophyte growers ask “What if I go away for several weeks in the summer and there is no one to water the plants?” The response is “That’s wonderful”. Experienced growers use the break in the rainfall during July and August to dry their plants “hard”. Depriving orchids of water for several days until they and the media or baskets they grow in are bone dry is essential to good orchid culture. By drying the plants hard, one deals a severe blow to orchids natural enemy, fungus. Orchids have evolved to withstand drought because fungus can not. During severe drought fungus’ only defense is to cease all growth and retreat into a spore stage. Hopefully (and with good cultural management) these pathogens will not be aroused from this slumber until the first drizzle of September sets in, allowing our plants two months to mature and harden their growth making them less vulnerable to the September conditions which give some advantage again to the fungi.

Careful watering and judicious drying will do more than any other practice to ensure healthy plants. Drought is the orchid plants armor against disease. Be sure that your plants dry as completely as the weather of July permits. Nonetheless, as our plants are in full growth they need adequate water in July therefor after a hard drying, orchid plants need a thorough re-hydration. If the next rain fall is insufficient to saturate pot, roots and media, the grower should add to the natural moisture until he is sure both roots and media are saturated, using two or three applications of water spaced a few minutes apart. When the plants stop dripping is the time to apply the next dose of water. Don’t stop watering until the “heft” of the pot tells you that it is holding as much water as it can. More typically in July, orchidists should use these opportunities when more moisture is required to substitute fertilizer for water and saturate the roots and the media in the same thorough manner. In July typically think of fertilizing rather than watering. Weekly application of a commonly available balanced fertilizer (20-20-20 or 18-18-18) at two teaspoons per gal. will supply the nutrients that our plants require in this period of lush growth. This balanced formula should be alternated every other week with potassium nitrate and Epsom salts (one tablespoon each) to supply the extra magnesium and potassium we now know are plants need on a regular basis. Even better (although not so readily available) lower phosphorus fertilizers containing extra magnesium and calcium with a formula like Peter’s Excel (15-5-15) have been shown to be the precise fertilizer our plants need. This formula is recommended year round. Hopefully such orchid specific fertilizers will become more widely available. Lowering the phosphorus intake of our plants is particularly important in South Florida because of our alkaline water. Always apply fertilizer in the same way as water, in two to three doses spaced a few minutes apart. Apply the fertilizer to the point of “run off” IE.when the solution starts to fall off the plants; stop and move on to the next plant. Repeat the application a few minutes later when the plants stop dripping. In July more than ever, never, never follow the frequently heard and disastrously bad advice of watering before fertilizing. Always substitute fertilizer for water: now and at every season. Roots saturated with water cannot absorb fertilizer but the prolonged wetness can rot your plants. Don’t give fungus the upper hand by wetting the plant’s foliage and roots more often or longer than necessary. Careful watering is especially important throughout the rainy season.

The wise orchidist will have long since finished all of his potting of sympodials and the top working of his vandas but for the rest of us this is the eleventh hour. Autumn is closer than we think and vandas will need at least three months to settle in to their new baskets or pots before the first chill of October tickles their root tips. Unless you can protect them thoroughly from cold, Vandatop cuttings and keikies should not be made after the end of July. If you do take cuttings remember the “3 root rule”. Count down from the crown and make the cutting beneath the third or fourth root. Keep as many leaves as possible on the stump and you will be rewarded with a greater abundance of offshoots. Always slip the sterile knife or shears down between the stem and the leaves and then cut transversely to save as many leaves as possible. Be sure to anchor the cutting firmly in its new lodging. Tie them up and tie them down! There is no time for mistakes in July.

Thrips are much less of a problem in July as the rain tends to wash them away and doubtless there is an abundance of other lush fodder for them elsewhere in our yards. They can reappear in a prolonged patch of dryness, so if you need to think of watering in July it may be dry enough to worry about thrips. A prophylactic spraying for thrips in July will also put a damper on scale crawlers. If a second spraying with soap follows the first by seven to 10 days, the population of mites will be scotched as well.

Motes Orchids 1/22/19 Motes Orchids 1/22/19

Treating Cold Damaged Orchids

Cold damage appears on orchids as whitening of the foliage and stems. The white gradually turns to brown as the effected tissue dies. Often this dead tissue simply dries and the damage is limited to the unsightly patches that are left. Frequently, however, the damaged tissue is infected with bacterial rot which can spread in the plant and cause further damage.

Softening of the edges of the cold damaged areas or oozing of brown fluid indicates bacterial infection. Removal of the leaf or stem is a simple but somewhat drastic solution. If one is loath to lose so much of the plant, the most effective treatment for bacterial infection is treatment with cupric hydroxide (Kocide or Champion) which should if possible be combined in equal parts with mancozeb (Manzate or Dithane M45).

This combination is packaged, pre-mixed as Junction. By adding a small amount of water to the chemicals in a jam, one can make a slurry that can be brushed on the lesions.

Be cautious when making the slurry not to inhale any of the dust and never, never, dust these chemicals without wearing a mask.

An old toothbrush is efficient in applying this and your dentist will be happy to have it out of your mouth. Any left over slurry can be placed on a high shelf (brush and all) and re-hydrated later. This stuff is also the cure for those soft spots that appear on Phal. leaves in summer.

For large collections, with extensive damage, one tablespoon per gallon of cupric hydroxide and mancozeb can be sprayed. Mix the two and wait an hour or more before spraying. Do not apply this mixture to dendrobiums which are hyper-sensitive to copper or to bromeliads (ditto).

Motes Orchids 12/8/17 Motes Orchids 12/8/17

Cold Temperature Tolerance of Different Orchids

One major obstacle for neophyte growers is in understanding the diversity of cultural requirements of various genera of orchids. Orchids are such a vast group of plants which have succeeded in nearly every conceivable habitat on earth, that knowledge of a specific genus’s cultural requirements, rather than a general knowledge of what “orchids” like, is necessary to successfully cultivate the various types. Most cultivated orchids come from tropical regions but differences in elevation and other geographic features of their native habits can mean dramatic differences in the response of orchids to various external conditions. Most emphatically these differences can be seen in different genera’s toleration of cold. While some orchids are native to regions where frost is more the norm than the exception, others are hyper-tropical plants for whom 50 F (10C) is far too cool. Knowing which is which is essential in a mixed collection of orchids. A great irony for beginners is to discover that their extra nurturing efforts to protect certain orchids have in fact done more harm than good.

Dendrobiums are among the most confusing for new orchid growers. This huge genus, well over a thousand species divided into 15 sections, ranges over nearly a quarter of the planet. Found from western Indian all the way to Micronesia, dendrobiums inhabit an incredible variety of ecological niches. Ironically, the two sections most common in horticulture are diametrically opposite in cold tolerance. Section Dendrobium, the soft bulb or “nobile types” whether in their pendulous forms like D. anosum and aphyllum or in the upright types like D. nobile and its hybrids, positively relish the cold. Temperatures right down to frost are the best culture to produce the most prolific blooming of these plants. Without cold and drought stress in winter these plants will retain their leaves and produce an abundance of vegetative growths but few if any flowers. Stressed by cold and dried out properly these plants lose all their leaves and in spring the bare bulbs are covered in flowers. The opposite is true for the “hard cane” dendrobiums of sections Spathulata and Phalaenanthe. Loss of leaf on D. phalaenopsis types is usually indicative that they have suffered from too much cold. Temperatures below 60F (15C) can produce this undesirable effect. D. phalaenopsis and evergreen types should receive the maximum cold protection.

Other sections of the genus have slightly different tolerances. Section Callista, D. farmerii, D. lindleyii (aggregatum) and their relatives can take temperatures nearly as low as the nobile types and will bloom all the better for exposure to temperatures in the 30's (3-5C). Section Formosae, D. formosum, D. infundibulum and the new hybrids prefer slightly warmer conditions but are quite happy with temperatures in the 40's (6-9C). Other sections of Dendrobium in cultivation such as Pedilonium, Latouria, and the Australian hybrids of section Dendrocorne have slightly different requirements and those growing these more “exotic’ will succeed best in researching them. Try B. Lavarack et al. Dendrobium and its Relatives, Timber Press.

After the cold sensitive “hard cane” dendrobiums, Phalaenopsis are the most tender of commonly grown orchids. Phalaenopsis will be strongly induced to bloom by temperatures in the mid 50's (12-13C). A few exposures to temperatures below 60F (15C) will produce the desired spikes and thereafter the plants will be happiest if they are kept above 60. One or two nights down to 50 or slightly below will do little harm but are to be avoided in the best kept collection.

Vandas come next on the scale of sensitivity. Like Phalaenopsis they are stimulated to bloom with sharp drops of temperature into the 50s at night, especially when the temperature can be induced to climb into the 80's (27-32C) by day. Vandas will tolerate brief excursions into the upper 40's but are best keep above 50 degrees. Temperatures below 50 for very long or very often will produce the tinkling sound of falling Vanda leaves, turning the plants into palm trees. 52.

Oncidiums of the “mule ear” type with thick fleshy leaves (O. luridum, lanceanum etc.) have warmth requirements similar to vandas. The thinner leaved Oncidinae will usually take temperatures into the 40's with aplomb. Many of the hybrids in this group have been bred to Miltoniopsis and to Odontoglossum to increase their cold tolerance. A caution with this group is the ability of wind to strip heat rapidly from their thin leaves. The cold tolerance of these will be much greater in still air.

With the exception of some species of Amazonian origin like Cattleya violacea, most cattleyas can take quite cool temperatures. Most growers have few concerns for them even in temperatures down to the upper 40's (8-9C). They must, however be protected from both frost and freeze. Be extra cautious on those clear still nights when the temperature drops to the 30's (3-4C).

In addition to the cold loving nobile dendrobiums, certain other genera from the high Himalayas such as deciduous Calanthe and Cymbidium species and hybrids, actual require quite cold temperatures to stimulate them to their best bloom. Even “warm growing, temperature tolerant” hybrid cymbidiums flower best when chilled repeatedly into the low 30's.

All orchids tolerate cold best when they have proper nutrition. Avoid too much nitrogen which might stimulate too soft of growth and increase the dosage and frequency of application of both magnesium and potassium in colder weather.