The most beautiful orchid in the world is Disa grandi~ flora, called by African natives the "Flower of the Gods." Later it was colloquially nicknamed the "Pride of Table Mountain," from whence—on the southern tip of the Cape of Good Hope—it comes. Unfortunately, disas were once considered difficult to cultivate and still have that undeserved reputation. The plants also are scarce; they were exported in such great numbers that their limited native habitat was stripped nearly bare of plants until the Union of South Africa stepped in and forbade further exploitation of them.

Apparently disas failed in cultivation because of the difficulty of reproducing artificially their native conditions; and, except for Disa grandiflora and Disa racemosa, their culture continues to be obscure. Consequently, few commercial growers possess more than a limited number of plants, if any at all, although some are still offered by British growers. It is unlikely that you will grow disas or that in the near future they may be grown more commonly. They are included here in a frank effort to stimulate enthusiastic amateur orchidists to collect some plants by hook or crook and to grow them so persistently that they become more reasonably available.

Ðisas are terrestrial orchids with a tuberous, fleshy root from which a rosette of leaves is produced. The flower spikes appear in spring, bloom in July and August, and last for months owing to their thick, waxy sepals and petals. The predominant color of the favorite, Disa grandiflora, is scarlet, cerise, or flaming red; some of the lesser-known species—whose flowers are usually small—may have a bit of yellow, white, purple, brown, or even blue and green in the flowers.

The one to six flowers on each stem of Disa uniflora are from four to five inches across. The dorsal sepal is helmet shaped and helps to give the flower something of the appearance of oddly shaped tulips. Disa racemosa, as its name implies, bears from six to twelve flowers on one side of the stem; each flower opens in slow succession making the blooming period last for three months or longer.

The original trouble in cultivating disas sprang from the reluctance of early collectors to divulge the habitat of the plants. Later, their peculiar growing conditions were overlooked because the plants were so much in demand that exporters didn't bother to check. In South Africa Disa grandiflora grows along the edges of streams and on the ledges of waterfalls; in winter such streams frequently overflow their banks, inundating the plants. Many disas have even been found in the beds of streams, with water constantly about their roots except during the dry season. As the streams dry up toward midsummer, disas begin to bloom. When in full bloom the plants are nearly always on dry ground, though considerable soil moisture is retained and water seepage from the streams keeps the soil around them moist.

This condition in nature must be duplicated in cultivation; enough moisture must always be available to disa tubers to keep them firm and plump. But because you can't see the tubers in cultivation, it is a bit troublesome to determine the correct amount of moisture. Again, it is the rule of never too little and never too much, and the best way to follow this rule is to have a compost which drains very rapidly.

Most disas are shaded by the low surrounding vegetation, at least until they bloom. The flowers themselves are nearly always exposed to full sunlight. This is not a difficult combination to duplicate in cultivation. Merely give the foliage all the sunlight it can stand and the flowers will take care of themselves.

Another natural condition must be borne in mind. Collectors who have made a profession of locating disas unanimously report that the plants' roots and tubers are so loosely embedded in the peaty, sandy soil that they can be pulled up without injuring the plants. It is important to bear this in mind when potting disas. Give them a loose soil which has not been firmed.

While it gets fearfully hot in South Africa, disas are never found at the lower levels where the temperature is extreme. Usually they grow at elevations and on plateaus where the average mean temperature is 60°. In cultivation this means that they should not be grown at temperatures above 90° or below 32° for any prolonged interval. They can withstand some frost but it is a hazard. They can withstand high temperatures, but they must be syringed or hosed frequently.
As quickly as their cultural conditions were learned, disas became common plants. Charles Leach of Clapham Park as early as 1825 grew disas experimentally in cold frames and unheated greenhouses, providing them with the cool, moist, semishady, and well-ventilated environment in which they do best. It is reported in early orchid magazines that he grew them like weeds.

In most sections of the United States, disas are best adapted to pot culture in cool, shaded cold frames with some sort of mild warmth during winter frost and snow. A gentle ground heat from leaded electrical cables-placed on top of the cold-frame bed—when the temperature drops below 32° seems about right. From late spring to early fall they can be placed in outdoor gardens in cool rockeries or ravines where ferns acclimate themselves easily. They are equally suitable for the cooler east windows indoors.

The first condition to keep in mind about growing disas—as with many tropical plants south of the equator—is that their growing season is botched up in cultivation. Their winter, when they bloom, is our summer. Their growing season is our winter and spring. This means that our northern temperate zone is basically unfit for them; we must adapt our conditions to meet their requirements. Give them all the sunlight they can stand during winter and some warmth to induce steady, continuous growth in new shoots. In spring and summer they will need continuously heavier shading, but be careful about giving them too much, for they need the right amount of sunlight to stimulate flowers.

The best pots for disas are shallow fern pans, not the deeper and more usual clay pots. One-third to one-half of the pots are filled with gravel. This is a "must" in order to facilitate extremely rapid drainage. You'll be surprised how little compost disas actually need; two large handfuls of leafmold and gravel (equal parts of each) are not too little; much more than that may prevent the compost from draining as rapidly as it should. Disas were the first orchid to have leafmold incorporated into their compost. They did so well in it that growers began adding it experimentally to other terrestrial orchid composts; today it is a standard practice with most terrestrials.

It is debatable whether a small addition of peat moss or sphagnum that has been chopped fine is beneficial in retaining moisture in the compost. In many instances moisture-holding materials may keep the compost wet too long; and although disas when in full growth can't be overwatered, they still must be well aerated at their roots. In practice, a mild soaking each morning and a mildly dry compost toward night are more desirable. Old growers also added manures to their composts, but the practice was of uncertain benefit, since disas are highly susceptible to manures and easily rotted. Yet they are heavy feeders and will require supplemental food during their growing season. Adopt a program of feeding them with a nutrient solution weekly in winter, perhaps as often as twice weekly in spring and summer, and not at all from the time they stop blooming until new growth is again initiated.

Here again your watering and feeding frequencies vary with the weather: little and seldom when cold, more frequently when warm. Once a month or every two months water them with a very weak solution of manure water. The natural hormones and organic salts of manure water will give them a boost; but don't overdo manure-water applications. Ðisas require more nitrogen and phosphorus than most terrestrials; such mineral salts are best found in a balanced nutrient solution.

Disas should be repotted each year in fresh compost just after they begin new growth. Usually this occurs in January or February. They sucker freely around the old tuber, and these offshoots can be cut away and potted to increase your stock. Once the tubers have been exposed to air, repot them immediately. The tubers are very soft, and undue exposure to air dries them out; they either die or produce weak growths which eventually succumb.

In potting, hold the crown of the tubers on a level with the rim of the pot. Add the compost and finish it off by sloping it downward and outward so that an inch or two of space will be available for water. Don't pack the compost or firm it; it must be loose. Any air pockets in the compost will be compacted by the first watering or by gently knocking the base of the pot against the top of the potting bench. Leave only the thinnest layer of compost over the top of the tubers. The rosette of leaves is formed very close to the crowns of the tubers.

If the pots are placed in a cold frame, plunge them up to the rims in gravel; disas benefit by a cool root run. Some similar provision for keeping the pots cool might be advisable in house culture. Water the pots frequently but lightly until the new growth is sturdy and well developed; then water copiously. Some growers like to water disas overhead, wetting the foliage as well as the compost; on hot days they may do this two or three times. Normally a good syringing will do as much good; too much hard or alkaline water on the foliage may tend to spot it.

When the flower stems appear in late spring apply less water than before. As the buds form and open, don't let water touch them. Rain doesn't seem to injure the flowers in their native habitat, but in culture water of any type will nearly always spot the flowers. The foliage, however, still must be syringed. After the flowers disappear, water much less frequently, but don't let the compost ever get really dry. Add just enough water to keep the tubers healthy. As the foliage dries up and falls away, you can gently move the top layer of the compost aside to check the condition of the tubers.

Should you make up your mind to grow disas, try the larger American firms first; but in all probability you will secure them more quickly from English growers. A few amateurs have written directly to South African botanical museums and arboretums and have been able to secure a small amount of seed. In many cases, though, the seeds have not been viable, owing to long delays in shipping and improper handling. Disa seeds must be enclosed in cellophane envelopes which are inserted into tightly stoppered dessicator tubes (see Chapter 10). Tubers are wrapped in moist sphagnum and carefully boxed.

However, whether you get seeds or plants it is wise to have them airmailed to you. The journey is much more rapid and is within the safe limits of seed and tuber viability. Most ocean journeys are much too long. When you receive either seeds or tubers, plant them immediately; don't let even an hour lapse before you get them into pots or seed pans. Disa seeds, incidentally, don't require any tedious laboratory technique to get them to germinate. They are sown and treated in the same manner as the seeds of tuberous begonias. Scatter the seeds over shallow pans of finely sifted leafmold that have previously been moistened thoroughly. Place the pans under a bell glass in a cool, shady, humid spot. Never let the compost dry out; either syringe it with a fine mist spray very gently, or bottom-water the pans; in fact, both methods of watering should be used. Turkish toweling stretched over osmunda is also a good base for germinating disa seeds. Nutrient agar gels aren't too successful. As soon as the seedlings are about an inch high, prick them out and pot them in small pots. They should develop blooming-sized tubers in about three years.

Before you try to obtain disa tubers and seeds from abroad, make arrangements with the United States Department of Agriculture for their importation. Write to the Bureau of Entomology and Plant Quarantine at Ho-boken, New Jersey, and get an import permit. Make arrangements with them for your plants to come to the United States by air mail and after examination to be air mailed directly to you from the port of importation.

The importation of plants can sometimes be a lot of bother, but it is always a thrill. It is very satisfactory to be able to say to friends, "This plant came from Mexico, and that one from India!" It does, however, presuppose some additional knowledge over and above that of just growing plants. Imported plants must be correctly packed before they are shipped, and often you alone can prescribe this.

And when you finally receive them, they must be treated in special ways. The best and quickest way to secure this knowledge is to go to your nearest city or county Farm Adviser—a branch of the state and federal agricultural agencies—and tell the staff what you want to do. Farm Advisers not only have pamphlets on the subject, but most of them will be experienced in the ways of importing plants and can give you many wise and timesaving ideas; you will find their know-how beneficial and stimulating.

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