Orchid Repotting

With the appearance of the long-awaited first flower in her greenhouse, the amateur quite justifiably feels a warm glow of achievement and pride.

She will find, however, that this is no time to bask in the glory of the moment, for, almost overnight, the greenhouse has quickened with life.

New growths glow a healthy red and the emerald-green tips of new roots peep from the potting mixture and even from breaks that are apparently dead roots. These are signals that the potting season is at hand.

The demand of the orchid for periodic orchid repotting is another characteristic setting it apart from other plants grown under artificial conditions.

It is common to most orchids out of their native environment. Just as important as housing and balance, repotting may appear to present almost insuperable obstacles to the inexperienced grower. The difficulties, if advice against overcrowding the greenhouse has been heeded, will not prove to be so great.

Orchid repotting is not something that can well be postponed, for, once the precise moment for repotting is past, it is best to hold the plant over for another year—the only exception to this being in extreme cases involving the life of the plant.

This enforced holdover may result in retarded development and the appearance of a smaller new bulb.

Next season's flowers may be fewer and poorer or there may be no flowering at all. It is one of the paradoxes of orchid growing that the plants require repotting at regular intervals, yet they resent shock and suffer from the procedure if every circumstance is not just right.

The best time to repot varies by genus but in most cases it is soon after flowering when the live eye at the base of the most recent pseudobulb begins to swell and form a new growth. It should never be done unless the plant is in active growth.

Orchid Repotting in flower sheath is inadvisable, since it usually results in loss of the flower. The ideal moment is just before the tiny new roots break through the tissue. If the plant can be caught at just this time and repotted without injury to these budding roots, they will immediately take hold of the new medium and the shock will be comparatively slight.

There are some plants that are such prolific and vigorous growers that they put out new growth and a flower sheath at the same time.

In such cases it will be wise to repot when the bulb has attained a size larger than that of the previous year, provided that no dark shadow of bud appears at the base of the flower sheath when the plant is held to the light, and that the roots show sign of strong and immediate growth.

Friends of orchidists often remark that growers spend much time in the greenhouse, seemingly doing nothing but brooding over the plants.

But there is purpose in this 'brooding.' Careful inspection of the base of bulbs will occasionally reveal a need for repotting that would be missed by cursory observation.

If growth of the new bulb progresses too far or if the roots become too long, it is almost impossible to repot without knocking them off.

New growths appear as though by magic but may remain undetected for a considerable time unless the plant is watched closely. It is an incidental reward of such care that other damage may be avoided.

The base of a bulb is a favorite hiding place for scale, and the pest may have injured the new shoot before being discovered. Sometimes, too, it is found that the new eye has been buried in the medium and the new growth has rotted off.

Careful removal of surplus compost with the tweezers will free the base of the bulb without injuring the plant.

Aside from the known requirements of a particular orchid, to be learned by experience and research, there are certain indications of a need for repotting that will be obvious to any beginner.

One such sign, although not always to be trusted because of the sprawling nature of some roots, is the appearance of many roots ranging out of the pot and over the potting material.

There is an urgent need for repotting when new bulbs are crowding or overhanging the edge of the pot or climbing awkwardly in the air.

Repotting orchids should have taken place long before such conditions appeared and the plant may be retarded by this neglect. Equally obvious is the case of a plant that has exhausted its compost.

The compost will appear entirely decomposed and will feel spongy and soggy. In spite of the risk involved in potting at the wrong time, it is best to remove plants at once from such unhealthy conditions, since otherwise rotting of the roots, loss of leaves, and death of the plant may result.

The question of the most suitable material for potting orchids is a matter of considerable debate among hobbyists. In making a decision it will be wise to refer to the native environment of the orchid.

Many of the showy orchids popular among amateurs are aerial-rooted epiphytes, receiving much of their sustenance from mineral salts in the moisture of the jungle air and from the debris washed into the crotches of trees on which the plants hang for support.

It cannot be expected that they will thrive after being cramped and packed in ordinary garden potting material. A special medium is required—some coarse, fibrous, and porous substance with an acid reaction of 4.5 to 5, which will not decompose too rapidly and so make the need for repotting too frequent.

English growers formerly used with success a native fibrous peat, but the supply of this material is near exhaustion. Since the war many fine British and Continental orchid collections have suffered from the lack of suitable potting media.

Potting in tropical localities, where orchids can be brought in from the jungles and hung in the garden, presents no difficulties. Cocoanut half-shells with broken shells for a medium are frequently used. Manuring is usually an essential part of such outdoor culture.

While the problem of the American grower is not so easily solved as that of the orchid enthusiast in the tropics, she is more fortunate than European orchidists. The special needs of orchids are met very satisfactorily by the use of Osmunda fiber—the root of the cinnamon fern, either Osmunda cinnamonea or Osmunda Claytonia.

In addition to providing the required drainage and pH, it is clean, easily handled, sufficient in itself as a medium for most orchids, and found in abundant quantities in New Jersey, Indiana, and the swamps of Florida.

The only rival of Osmunda as a general orchid-potting medium is Polypodium, root of the fern Polypodium vulgare. It is found over much of the world, with the Pacific Northwest of the United States as a favored locale. In certain respects Polypodium is better than Osmunda.

It decomposes as rapidly and has a finer texture, particularly suitable for tiny seedlings, backbulbs, and sick plants. A mixture of chopped, live sphagnum moss and finely chopped Polypodium is a recommended formula for plants in poor condition.

The drawbacks of Polypodium, however, still make Osmunda the choice of most growers: it is more difficult to water plants in Polypodium; if not saturated it dries out more quickly; and when saturated it does not drain so well. It is difficult to change plants from Polypodium to other media without setbacks.

Proper equipment is the next requirement for a successful orchid repotting operation. A sharp, strong knife will be needed to make a clean cutting of roots clinging to the pot.

A screw driver is valuable for freeing the compost and plant without damaging plant or pot. It is also handy for tucking compost into tiny seedling pots. Some type of shears will be indispensable. Grape shears with long, slightly curving, pointed blades are excellent.

The potting tool proper is often a matter of the grower's ingenuity. Many types are in use. Highly recommended is a piece of hardwood (such as a broom handle) about 12 inches long and from 1 1/2 to 1 3/4 inches thick, smoothed to fit the palm at one end and sharpened to a point, or flattened to a sharp wedge, at the other.

Some growers prefer a metal tool, since it allows the use of more pressure in packing the medium firmly.

This may be a flat blade of heavy metal about 1/2 inch thick and 1 to 1 1/2 inches wide, shaped to an 'L,' and filed to a flat, moderately sharp edge at one end. The other end may be covered with a piece of rubber hose to protect the hand.

Some growers use stakes of redwood or bamboo to support weak or leaning bulbs, but supports of heavy galvanized wire, cut to a suitable length, will best survive the continued damp. String or flat dental floss may be used for tying material; raffia is not advisable as it deteriorates too rapidly when it dries out.

Tweezers are useful for removing dead tissue from the bulbs and decomposed compost from roots. At times the dry tissue at the base of the new bulb may become chilled when wet and a wet fungus sets in that may affect the entire bulb if not removed.

Care should be taken not to injure the dormant next-year growth under this tissue.

The type of container used will depend on both the need of the individual plant and the taste of the grower. Pots are most suited to Cattleya and allied genera, to Cymbidiums grown under glass, and Cypripediums.

On the West Coast, where plants will not dry out too rapidly, fern or half pans may be used. Deeper containers are needed in hot and dry climates.

Phalaenopsis can be grown in pots or baskets. Oncidiums and Wanda coerulea thrive on rafts of bark or blocks of wood. Potting material may be tied firmly around the base of the plant and container with wire, allowing the air-loving roots to wander at will.

Certain plants (all Vandas, some Laelias, and Coelogyne cris-tata) react so badly to repotting that it is best to resort to other expediencies.

Decomposed material may be removed from between the roots with tweezers and fresh material gently tucked in its place. In the case of Laelias in baskets, with roots ranging far outside, fresh material in the form of a feed bag may be wired around the outside of the basket.

After fresh material is tucked around Coelogyne cristata, the bulbs that are growing in wild abandon may be fastened back in place with wire hairpins. In selecting the proper-sized pot for a plant, choice is governed by the health, size, and habit of growth of the particular orchid.

For example, plants such as the Cattleyas, with a running rhizome-type of growth, may be potted to allow for two years of growth, a growth to a year, and an inch of pot to a growth.

Generally, a large healthy plant will require a large pot, while a weaker, slower-growing plant needs a smaller one. A sickly plant may sometimes be brought back to health by confining it to a small pot.

Overpotting, an error which many beginners make, is a costly practice. The roots of the plant will not be able to absorb all the moisture in a large pot.

Excessive moisture settles in pockets in the potting medium and rapidly decomposes the compost. When this condition prevails, roots tend to rot off, bulbs shrivel, and leaves turn yellow.

An inexperienced grower, concluding that these symptoms are caused by a lack of water, may overwater, completing the damage to the roots and killing the plant. Cleanliness is important in repotting.

Old pots and crock (broken bits of pots used in the bottom of a pot for aeration and drainage) should be scrubbed thoroughly. New pots should be soaked for a time.

As a concluding word on the subject of equipment, the grower should remember that 'A proper place for everything and everything in its proper place' is a wise maxim. The best arrangement is to have a clean, light potting shed adjacent to the greenhouse.

The major furnishing of this shed should be a potting bench of a height suited to the potter. A comfortable height is advisable, or potting may become a back-breaking job.

A specific example will provide the most understandable picture of potting procedure. Let us take a Cattleya plant with Os-munda as the medium; the method will be similar for other plants with certain exceptions that must be discussed separately.

The Osmunda, after dirt and foreign material have been shaken from it, is chopped into pieces about four to five inches square, cut with the grain. The medium is easier to handle if it has been sprinkled with water the night before.

Old clinging roots are severed from the pot with a sharp knife, and the compost, containing the undisturbed plant, is forced from the pot with a screw driver. The roots are shaken free from decomposed material.

Dead or long roots are trimmed slightly, since they would be injured in potting anyway. On a mature plant most of the backbulbs will be found to have no roots and, usually, no leaves.

Three to five of the newer bulbs are left; the rest are cut from the plant and, if they are lacking leaves and roots, and are true backbulbs, they are labeled and kept under the bench, dark and damp, until dormant eyes break.

The plant is now inspected for pest or fungus, for which it may be treated with a safe insecticide and a small brush.

If it has not been possible to save some of the good Osmunda on the forepart of the plant or if for some reason the roots have been destroyed, a soft ball of Osmunda is tied to the base of the plant as a foundation on which to work. It is often well to enlarge the hole in the bottom of the pot to give the drainage and aeration needed by epiphytes.

Some growers use a single piece of crock in the bottom, while others fill as much as one-third of the pot with crock—bits of brick, coke, haydite, or gravel may be used instead; in any case, the hole should not be tightly covered.

With the plant held firmly in one hand about one-half inch below the top of the pot, the back of the plant close to the edge of the pot, and the growing end toward the center, potting begins.

A piece of Osmunda is held at a right angle to the top of the pot with the grain also running at a right angle to the top; with a little flip of the potting tool, so that it never touches roots or plant, the chunk slips neatly in place within the pot, to rest vertically and against the plant.

This procedure is repeated, from side to side, until all the gaps are filled, each chunk being made shorter as the edge of the pot is approached. If the plant leans to one side it can be straightened by adding Osmunda to prop it up.

The beginner often feels that experienced orchidists place too much emphasis on packing the medium tightly in the pot, but there are good reasons for this emphasis. Cattleyas require firm potting so that roots will have a strong hold on the medium.

Plants that are held weakly may wobble and roots may be broken. Firm potting also prevents plants from falling out of dry and shrunken compost and keeps water from settling in holes and rotting the roots. It is wise to spread the roots, packing Osmunda among them for aeration.

There are many methods of packing the medium into the pot, but the one outlined is a good workable way of doing it and seems to pack the medium more satisfactorily than just to force it in without regard for direction.

Some growers favor severing the rhizome while the plant is still in the pot, dividing it some time before repotting, and thus encouraging new roots and growths without disturbing the plant. This is a good plan and sometimes saves a year of growth.

Whatever the method, the potting material should be worked in without letting the potting tool touch the roots. Success depends largely on the roots' being disturbed as little as possible. If the tool is pressed against the edge of the pot for leverage and the material worked toward the center, only the medium will touch the plant.

A further and equally necessary precaution is to take care that the rhizome lies along the top of the potting material and particularly that the dormant eye is not buried. This may be difficult if, owing to failure to repot in time, the plant has started to form new growths up in the air.

Even so, the rhizome must be placed along the top of the material and the bulbs gradually tied into an upright position.

Even after the amateur has decided he can force no more Osmunda into the pot, it is usually wise to try again. It is surprising how many times the pot will be found not nearly so full as it was believed to be. When the pot is full, the stake is inserted at the back of the plant and the bulbs are tied up.

They should be tied firmly enough to prevent a movement that will break off roots as they form, but not tight enough to choke the bulb or to force it so suddenly into an upright position that it will snap from the strain.

The label is placed toward the back of the pot, and the pot is then set aside in a place especially designated for newly potted plants.

Some growers do not believe in watering until the new roots are well established; others let the repotted plant go unwatered only a few days or, at most, a week. There is no object in watering until the roots are at least formed because until then the plant cannot use water.

A light, daily overhead spray will be sufficient to keep the leaves green and bulbs plump until the roots do form, which may take as long as three weeks.

Labels are very important and should not be lost or placed on the wrong pot when repotting. Many types are available but only those that are water-resistant are satisfactory. White or colored labels of celluloid, dull on one side for printing with a lead pencil or India ink, are ideal.

The potting method described applies to all Cattleyas, hybrids, and allied genera. Vandas, with their air-loving roots, must have different treatment. Vanda coerulea, especially, will do better on a raft than in a pot.

The roots will then be able to wander freely through the Osmunda tied around the base of the plant and the stocky aerial roots will break above the Osmunda.

One method of dividing a Vanda (not particularly recommended to the amateur, until he has at least gained some experience) is to cut off the top part of the plant below one or two of the big fat roots breaking from the stem.

The top part may then be tied on a raft, and both parts are supposed to grow and flower. This would be dangerous treatment for V. Sanderiana, a plant apparently loath to send out typical roots from the stem.

If Vandas are planted in pots, good drainage must be assured (at least one-third crock being used), and the plant should be well centered in the pot. Vanda Sanderiana, as has been indicated, is the most temperamental of the Vandas. It thrives in a large pot and reacts badly to repotting.

Old medium may be removed from the roots and fresh material tucked in its place. Repotting, with Vandas as with Cattleyas, makes a good time to check up on scale—a pest most detrimental to this plant.

Phalaenopsis give trouble to some growers. When potting, the plants should be well centered in the pot or basket. Medium should be well packed but not so firmly as for Cattleyas.

Compost should come well up around the base of the plant, since Phalaenopsis has a tendency to force the constantly forming crowns up from the medium. There should be very good drainage.

Osmunda makes a most satisfactory medium. Phalaenopsis are heavy feeders and will usually exhaust the medium in two years, after which they should be repotted orchid. This orchid has strap-like roots that wander out of the container and become fastened to it, the bench, or adjacent pots.

These roots must be severed in repotting, and the plant is inevitably set back. The intense interest in gravel culture, which is spectacularly successful with Phalaenopsis, is partly a result of this difficulty in orchid repotting.

Dendrobiums need to be repotted immediately after flowering since they start new growth almost at once. Osmunda agrees with them, although the addition of sphagnum is often helpful. The deciduous canes may be cut from D. nobile and D. superhum and laid on the gravel under the benches.

They will break at the eyes and form new plantlets. Dendrobiums may be accommodated in a variety of containers, but, since they thrive in confinement, the receptacle should be as small as possible. Rafts or baskets are suitable for the drooping types.

Drooping canes should be allowed to follow their inclination unless room is scarce, in which case they may be tied up.

Other types will do well in pots with Osmunda as medium. Sanders recommends a compost of three parts finely cut Osmunda to one part of sphagnum.

Coelogynes, with few exceptions, should be potted in shallow containers in firmly packed Osmunda. When repotting, the growths should be placed toward the center and the compost mounded. As they do not react well to repotting, it should be avoided when possible.

Rather than repotting orchid, some growers prefer to add fresh medium at the front of the plant. From time to time freshly sifted Osmunda may be sprinkled over the top and watered in.

Here again Sanders recommends a compost of slightly less than three parts Osmunda and a little over one part sphagnum.

Oncidiums, like Dendrobiums, do well in confinement. Their containers, which may be baskets or rafts, should be just large enough and, as a rule, hung in the light. Osmunda is a satisfactory medium.

When Oncidiums are potted in a basket there should be a great deal of crock and not much compost. Sphagnum may be added to the medium. The genus requires a lot of water and consequently adequate drainage.

A book might well be devoted solely to Cymbidiums. Every grower has his favorite mix of compost and these splendid plants do gratifyingly well in all mixes. They are terrestrials and so do well in straight soil, although they seem to do best on a rich, well-drained medium.

Old, clean Osmunda, collected when un-potting Cattleyas and other species, is excellent for this purpose. A formula highly recommended by a successful grower is three parts of leaf mold (oak and sycamore), one part disintegrated granite, one-half part fibrous peat, and one-half part turf and sand.

One grower's wife has been heard to complain that her husband tears up the front lawn to get potting material for his Cymbidiums. The use of fertilizer is a controversial matter, but it is probably good for these heavy feeders. Addition of leaf mold is always recommended.

Cymbidiums need moisture at the roots at all times and correspondingly good drainage. Since these plants grow enormous bulbs, a large pot is necessary. The time for repotting is late spring when new growths are just beginning.

Backbulbs may be removed without disturbing the plant and they will start new plants from the dormant eyes.

When potted the backbulbs should be centered in the pot since there is no way of predicting the direction in which the eye will break. They should be potted firmly, although not so tightly as Cattleyas, and they may be held fast with a stake.

Cypripediums have needs very similar to the Cymbidiums, but require more water and not such firm potting. Cypripedium roots are brittle and delicate and should be handled gently to avoid injury.

If the plant is soaked for several hours before being removed from the pot, the compost may easily be separated from the roots.

Cypripediums can be readily divided during orchid repotting, as they practically fall into separate plants, but, lacking pseudo-bulbs, they take up little room and there is not much need for separation.

Pots of four to six inches will be most convenient to handle. The plant should be well centered since new growth may break from any side.

This genus will do well with the composts used for Cymbidiums. The native habitat of the Cypripedium is usually swampy, so they need a rich, wet compost. One grower recommends a mix of almost liquid, mud-like leaf mold to be poured around the roots and kept wet. Osmunda, preferably partially decomposed, is effective.

A satisfactory formula for the green-leaved types is three parts loam, one part of Osmunda chopped fine, and one part sphagnum. The mottled-leaved varieties do better with a formula of one part loam to two parts of Osmunda and two parts of sphagnum.

Odontoglossums also require a rich, moist compost; they thrive in leaf mold and heavy soil. Osmunda tends to be too dry. Old Osmunda, the residue from previous repotting of other orchids, can be used in repotting Odontoglossums, and a bit of sand may be added.

Polypodium mixed with finely chopped Osmunda is also used. A more elaborate mix consists of sphagnum, fine-cut fiber, a little sharp silver sand, and a few decayed oak leaves. These plants do exceedingly well under oak trees in localities where they can be grown outdoors.

As Odontoglossum roots are very fine, the plants should be soaked before repotting so that the old material will fall away without injuring them. About two thirds of the pot should be filled with crock to insure good drainage.

Odontoglossums should be potted firmly but not tight. Water should be withheld until new roots form, and then frequent damping will see the plant through in good shape.

This genus does not react well to disturbance of the roots during hot weather, so September is the ideal time for repotting; growths will then be about an inch high and the plant will have a chance to re-establish itself before winter. Orchid repotting is also possible in March as new roots will have a chance to form before hot weather sets in.

Miltonias may be repotted at the same time as Odontoglossums. Straight Osmunda may be used. Another medium consists of equal amounts of peat and moss, with good drainage. Pots, not too large, are used as containers. Extreme care should be taken that repotted Miltonias do not receive water until new roots form.

When the first orchids were imported from their native jungles many years ago, thousands of plants died from being transferred to unnatural conditions under glass with the aerial roots crammed into unsuitable media.

Gradually but surely painful experience has evolved the modern treatment that is now so successful that hothouse-grown plants often far surpass jungle plants of the same species in beauty, and in number and size of blooms.

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