A number of beautiful terrestrial orchids of the southeastern United States have the reputation of being impossible to grow; they are species of sunny, wet, acid soils. While they may grow in wet pinelands, bogs and along the edges of cypress swamps, their main habitats are manmade roadsides, ditches, plowed seedling pine plantations and electric power-line savannas. They include species of Calopogon, Pogonia (including Cleistes), Spiranthes, Blephariglottis (or Platanthera, Gymnadeniopsis, Habenaria) and a few others. Many orchids of similar ecology occur in Brazil, Japan, South Africa, etc. and apparently present the same challenge to the grower. This article presents a reasonably successful method of growing these orchids and may stimulate further advances in growing and in breeding them.
A growing medium for any group of plants must meet several criteria before I would consider it worth using:
1) It must be reasonably priced. A medium that prevents disease or causes very rapid and strong growth can certainly be higher priced since it will pay for itself.
2) The materials must be readily available locally in small to large quantities, without long and unpredictable delays.
3) Materials must be reasonably uniform, so that mixes can be repeated reliably. They must be as free as possible of disease and other problem-causing contaminants.
4) Preparation must be simple and clear-cut, without involving large amounts of equipment, time, or energy. The complete process of preparation is best done in one short period of time, so that the medium can be made up on short notice. This also avoids the confusion and errors that often occur in an interrupted sequence of preparation.
5) The medium must be storable at least for some weeks, so that it can be made up in batches and then used as needed.
6) The medium must be simplified, with a minimum number of ingredients, rather than a little of everything, with two or three materials serving the same purpose (or lack of purpose). These few ingredients, as far as possible, should be the same ones used in other mixes for other kinds of plants.
7) Each growing medium must be usable for a large array of different plants, rather than a different mix for each kind. The above may seem obvious to the point of "ho-hum", yet it is amazing how many books and articles present media that fail on one or even several of the above criteria. A further point is less obvious, yet (to me at least) is vital:
8) The medium must be reproducible by other people; that is to say, it must be capable of clear, precise communication. This is actually a self-protective rule. If I cannot convey to someone else what I am doing, I am all too likely to forget or become confused with the passage of time. Many published soil mixes are pure gibberish. What is "loam," "a good garden soil," "a good fibrous loam," "compost," "a rich earth," "leaf mold," "ordinary soil," etc.?
In seeking media and techniques for growing bog plants, most published accounts have been of little help. Much of the failure is due to antiquated approaches, especially the assumption that the grower must seek to duplicate nature. Some recent articles by various carnivorous-plant growers, and a few orchid writings by Fred W. Case, Jr., have been exceptions to the rule. It appears that a number of people in different places have converged on the method outlined here, so there is little for which I can claim any priority. However, conversation with some of the most experienced orchid species lovers around Florida reveal a need to publish it all.
Many writers seem to assume that terrestrial orchids must be planted in the ground. Yet several of these same writers bewail the inevitable slugs, mice, snails, fungi, weeds, pH changes, etc. that result. Since epiphytic orchids are grown in the smallest pots feasible, some people seek to apply this rule to bog orchids. Large containers, with many plants in each, will be difficult to move about but will stabilize moisture and other factors. Always use plastic containers, such as dishpans, children's wading pools, tubs, buckets, mixing bowls, or shoeboxes. Never use galvanized metal, terra cotta, wood, or glazed containers. In most cases the container should be deep enough for 6 inches (15 cm) of medium plus at least 2 more inches (5 cm) above this surface. A few short and narrow knife slits should be made horizontally on the sides. These should be about 1 inch (2.5 cm)below the top surface of the medium, when it is settled in place. For a plastic dishpan, 1 or 2 such slits will be sufficient. Small mixing bowls need no drainage if the medium is level with the rim. Tilt them if they become too wet for too long. For a wading pool of 3 or 4 foot diameter (roughly 1 meter), about 5 slits will suffice. Wading pools are the best containers for growing and the cost per unit of area is less than for other containers. Note that in all cases the drainage will be above the halfway point in the medium, thus leaving a sizable depth and volume of permanently saturated growing medium below the plants.
All containers must be free of dirt and securely placed more or less level upon a strong bench. The bench top should be at least 20 inches (½ meter) high. A standard concrete block on its end, with a 2" X 4" frame will be just right. Hardware cloth or welded fence wire (not flimsy chicken wire) should be securely stapled or nailed on top of the wooden frame. Wading pools are too flimsy to support several hundred pounds of water and medium unless they are completely supported from beneath. The location of the bench must be in full sun all day or nearly so. Naturally, the medium must be added to the container after it is in the exact position desired. Never enclose these growing areas in any way; fresh air is essential, and cold is needed in the winter. An enclosed terrarium-type situation will kill most bog plants almost as quickly as if they were houseplants in a department store. Containers must be protected from the common "pests" that lean, pull, push, sit, or try to rest a foot on them.
For the growing medium, mix 5 parts of perlite, 3 parts of vermiculite and 2 parts of northern sphagnum bog peat. Exact ratios are not critical, but the above is easy to remember (adding to 10 parts total) and is easy to measure out. A little broken charcoal could be added to the top of the medium, if desired. I often like to add a little more vermiculite to the surface and then scratch it in lightly. The plants should be mostly clean of natural soil; small amounts will not matter. Fire ants must definitely be eliminated from the plants before they are planted in the containers. Plants should be right at the surface, with the roots spread horizontally just under the surface. Plants can be densely crowded, especially if various kinds are intermingled.
After the plants are in position place live sphagnum over the surface, especially clumping it around each plant. It may be gently pressed down, just enough to ensure good contact, or a careful sprinkling will settle it in place. In placing the sphagnum, make sure that the growing tip is erect. The importance of live sphagnum to many kinds of plants has long been known. Nevertheless, little effort has been made to utilize it effectively in gardening. Sphagnum on ordinary soils does poorly or dies; pure sphagnum in plastic containers is far better. In cooler climates perhaps it will suffice, but here in Florida, at least, it needs a substratum that is chemically acceptable and that stays uniformly wet. There are many different species of sphagnum mosses, but any Florida or Costa Rican kind seems to be satisfactory for present purposes, except a few that are floating aquatics. Plants can be labeled with plastic, never wood or metal stick-in labels; never use copper or other wires on the labels and never stick metal rods or pieces of wood into the containers for staking up plants. At later dates it will be necessary to add plants, and simply poking a finger down to open a place for them can easily do this.
Carnivorous plants, lycopodiums, various bulbs and wild flowers can and should be mixed with orchids in these artificial bogs. The sphagnum will grow so vigorously that it will flow over the rims of the containers in great masses. Very small plants, such as many Spiranthes, Drosera and Pinguicula species, will need to have this exuberance carefully controlled in their vicinity. Oxalis and other weeds (especially grasses) will have to be handpicked from the moss while young; this means conscientious effort about once a week. Tree leaves will probably blow in from some distance away and can be removed at the same time. The Asiatic orchid Zeuxine will seed into the moss and seems to do no harm.
Acid-soil plants definitely do not like fertilizers, metals, lime, fungicides, insecticides, slugbaits, weedkillers, water that is brackish, chlorinated, softened, hard or alkaline. Rain water, either directly on the plants or when caught in an all-glass or plastic container, is excellent. If other water must be used, it should be freed of all impurities and acidified. Some plants may prefer a little more peat around their roots, but it is usually a mistake to use too much. Most kinds will be better off with less peat and more vermiculite. The surface can be engineered to be uneven, with high, drier hummocks for Pogonia divaricata and Spiranthes vernalis. Lowspots, right down to water level, will suit Spiranthes odorata and S. laciniata. If it is desirable to move the plants about, such as for display in a botanic garden, use either the dishpans, or mount wading pools on 4-wheel flatbed dollies. Let me caution again that no fertilizers of any kind ever be used.
Those who wish to raise plants from seed may try the following procedure: use clear plastic shoeboxes. Either provide no drainage and water very carefully, or make a few small drainage holes on the lower part of the sides and water very carefully. Place some finely broken charcoal on the bottom, then about 1 inch (2.5 cm) of the above mentioned 5-3-2 mix should be added and gently settled in with a light sprinkling, then plant about 1 inch of live sphagnum (growing tips up) upon this. Sprinkle the orchid or Sarracenia seeds over the moss. Place the cover on and keep in a safe, shaded place. Results will vary but can be very good. In fact, epidendrums can be grown with unbelievable speed by this same method. Flasking of Australian terrestrials is now reported to be quite successful. Experiments with tissue culture of bog orchids, sarracenias, etc. are also underway.
Many of the "rare" and "endangered" orchids grow in colonies of thousands, even hundreds of thousands of plants. These sites are often on road shoulders where various governmental agencies work very hard to mow, defoliate, salt down, burn and chop down the vegetation, orchids included. Intelligent and constructive efforts to save these plants, especially when roads are being widened, should be made by private growers and by research institutions. No benefit to botany, horticulture, education or conservation results from covering an orchid plant with asphalt. The growing method discussed in this article generally does keep them alive and makes efforts to multiply their numbers successfully.
Minor modifications of this method allow the growing and propagating of "Jewel Orchids," gesneriads, begonias, aroids and many other tropical plants in the greenhouse.