Bear one thing in mind when potting orchids: Don't use glazed or painted earthenware pots! Though decorative, they are damaging to plant growth. They keep the compost overwatered and underaired—both fatal to orchids. Otherwise, potting orchids—except for the trick of packing osmunda—is no different from potting azaleas or begonias.
Select a clean pot several inches wider than the broadest basal width of a terrestrial orchid. Soak it for a few minutes in tepid water, then drain. Place coarse gravel, small rocks, or crocks (bits of broken pots) in the bottom third of the pot. Add several large handfuls of compost and shape to a cone, the top of which is on a level with the lower rim of the pot. Spread the roots of the terrestrial orchid carefully and evenly around the cone, and fill with additional compost. Firm the compost lightly to settle it— never pack it—and water thoroughly. Later, water sparingly until growth is established.
Some deciduous orchids, as Calanthe vestita, lose their roots. Push their pseudobulbs into the compost just far enough to hold them erect. Other terrestrials, those without pseudobulbs such as Oncidium cavendishianum, may have to be wired or staked to the top o£ the compost since their leaves would rot if covered. Such special characteristics are mentioned later, however, when we discuss the various genera.
The first time you attempt to pot a tree orchid in os-munda you will find yourself using the least desirable words in your vocabulary. There is a definite trick in handling osmunda. Old-time growers regarded potting as the most distasteful part of orchid culture. It was once believed that osmunda had to be packed into pots with great pressure, using special sticks as levers. If, when you lifted an orchid by its foliage, the osmunda came free from the pot your education in orchid culture was considered highly dubious. In the long run, all that packing osmunda achieved was a sore arm for the potter and injured orchid roots.
POTTING ARRANGEMENT FOR TERRESTRIAL ORCHIDS
POTTING EPIPHYTES IN OSMUNDA
It is now believed that such extreme measures are not advisable. As long as osmunda stays securely in place, holding its shape when knocked out of the pot, orchids will do satisfactorily. The trick in potting with osmunda is to handle it while it is slightly damp. It is pliable then and packs more easily. When it dries out it stiffens enough to firm itself in the pot.
Here is how you go about potting epiphytes. Take enough pieces of osmunda, sometimes called "orchid peat," to fill several pots. Soak the osmunda overnight in a pail of water. The following morning leave the pieces in a cool, dry, shady place. In the evening when you come home they should be just right for potting. They will feel soft, pliable, and somewhat damp—not wet—to your touch.
Take a clean pot at least two inches wider in diameter than the base of the orchid, soak it in tepid water for a few moments, then dry it out a bit. Soaking is not always necessary, but it helps the osmunda slide down the clay sides of the pot. Set the pot on its base and add enough gravel or crocks to fill it one-third.
Take the orchid in your left hand, the base (rhizome) resting on top of your thumb and forefinger. Smooth the roots over the back of your hand. Select a piece of os-munda as nearly conical in shape as possible. Put it beneath the base of the orchid, touching the rhizome. Spread the roots around it. With other pieces of osmunda—slightly less in length than two-thirds the depth of the pot—cover the roots. Work outward, in a circle, until the osmunda covering the roots is a little larger in diameter than the top of the pot. Squeeze the osmunda with both hands, pressing it into the pot with a sliding motion.
Further packing is accomplished by inserting the fingers of your left hand between the osmunda and the side of the pot. In the gap so formed slip another small piece of osmunda. Turn the pot slightly and repeat the process. Keep turning, squeezing, and adding osmunda until you have to exert some pressure; then stop.
An expert can pack osmunda so that an orchid rides on a slight mound in the center of the pot and level with the upper rim. The rest of the osmunda slopes evenly outward and down, meeting the inner rim of the pot and providing a water receptacle. This is not easily accomplished at first by amateurs. A pair of short narrow-bladed shears is invaluable in trimming the osmunda so that it slopes enough to make a small water receptacle circling the lower rim of the pot. The repotted orchid is watered thoroughly and set aside to dry out. Water is given sparingly thereafter until root growth is vigorous.
There are several schools of thought regarding the correct position of an orchid in a pot. Those who like a balanced pot center the orchid in it. Those who go in for efficiency place the oldest pseudobulb (the rearmost one) against the edge of the pot, thus leaving plenty of room for future development. This latter method is most in use since it permits an orchid to remain in a pot longer. Eventually, too, the additional new growth will tend to make the plant look balanced.
At this time it is important to stake your plants. Orchid foliage tends to slope too much, sprawl, and take up more bench room than is necessary. Cattleyas, for example, take up twice as much room if left unstaked. Other than cymbidiums, whose foliage is erect, and cypripediums or similar orchids, whose foliage is scant or low, most orchids will need staking, if for beauty alone. If lateral stems are not staked, flowers growing on them do not look well in exhibitions, are easily injured when moved, and are often unsuitable for house decorations or corsages.
Terrestrial orchids may be staked with thin but sturdy pieces of redwood or cypress thrust into the compost. A thick piece of galvanized iron wire (about twelve gauge) is more suitable for epiphytes; wire enters osmunda more easily and holds better. Ordinary wire clothes hangers may be cut into pieces and straightened to make excellent stakes. Place your stakes as near to the center of the pots as possible in order to obtain a more uniform appearance. The top of the stakes should not be more than an inch or so higher than the top of the pseudobulbs. Nearly any of the tying materials available in garden stores can be used, although soft string is about the best; it doesn't cut the foliage and can be closely trimmed to do away with dangling ends. As a rule, the string is circled around the top of the pseudobulb, at the joint with the leaf, crossed back to the stake, and knotted securely. Nearly all flower growths, if vertical, should be staked when a few inches high. The flower stems of monopodials which develop from leaf axils are not staked; neither are those from the stanhopeas which push their stems down through the osmunda and out the bottom of the orchid baskets.
ORCHID BASKETS AND RAFTS
The season for potting an orchid doesn't depend upon spring or fall, but varies with the season of bloom. It is best to repot after the flowers fade, when new growth is initiated and the root collar appears. The root collar is apparent with epiphytes, less so with terrestrials since it may be produced beneath the compost. The collar develops at the base of new growth and when first seen is a series of small bumps extending around the basal circumference of the growth. This is the time to repot if necessary. Later the protuberances elongate and become growing roots. At that stage they are brittle and easily broken during potting.
In preparation for repotting, knock the plant out of the pot, brush off the old, stale compost, and cut away the dead and decaying roots and foliage. If too many roots are dead, you have been consistently overwatering or your compost is not well drained. There are two good tests for roots. Epiphytes will have firm white roots when dry, slightly greenish ones when wet. Terrestrials will have firm brownish colored roots, both wet and dry. Dead roots will be dark brown and soft. Run your fingers down a suspected root; if it is not good the outer covering, called "velamen," will slip off.
Clean the foliage with a weak vegetable-oil-emulsion insecticide diluted to half the strength of the weakest dilution recommended on the label. Strong emulsions are injurious. A used toothbrush, well worn and soft, is excellent for orchid cleanup work. After the orchid is cleaned and trimmed, repot it as explained for terrestrials or epiphytes.
Many growers believe that repotted orchids suffer from shock, sometimes preventing flowers from appearing the following year. These growers prefer to leave orchids in their pots as long as possible—usually two or three years— without renewing the compost. Except for some deciduous orchids, this is good practice. Orchids grow better when not disturbed; but don't be tempted to overpot them on that account. Repot your orchids when the compost is exhausted, too alkaline, or the plants become too big for their pots.
In the old days some English orchidists were so convinced that orchid roots should not be disturbed that they developed a special technique. Pots were wrapped heavily with string. The sides were cracked apart with a wooden mallet, and pots, plants, string, and all were stuffed into new and larger pots. Fresh osmunda was inserted between the old and new pots. Roots were supposed to work through the cracked pots into the fresh osmunda. This method was abandoned as soon as it was learned that old osmunda was infinitely worse on orchids than the shock of repotting.
Recently, moreover, some scientists have questioned whether shock occurs. Orchids grown in gravel may be pulled out and replanted a dozen times a day without appreciable ill effects or loss of bloom. It is suggested that shock may be synonymous with carelessness, either in removing old compost or in the forced packing of fresh compost. When orchid roots are tightly pinched they may die because they often haven't the strength to repair injured cells. An orchid is only as vigorous as its root system is vigorous and extensive.
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