| Welcome to herbs2000.com - Number one source of traditional and nutritional health care. | |||
H O M E | |||
| |||
Repotting OrchidsThere are two main reasons to repot your orchids, and they often, but not always, occur at the same time. First, an orchid needs to be repotted if it gets too big for its pot. Orchids can have an extensive root system inside the pot and the potting mix, but they also typically have roots that extend out of the mix into the air, and this normal behavior is not usually a clue for repotting. But when the pseudo bulbs hang over the pot side or new roots can't find their way into the pot at all, then that orchid needs repotting. The second reason to repot is because the mix has decomposed. If they're made from natural materials, most potting mixes deteriorate with time, breaking down into a fine, tightly packed mix that closes out air. With no air, roots die, and the orchid is doomed unless it is released from that compacted environment. Recognizing deteriorationTo tell if an orchid needs to be repotted, you should brush away the top of the potting mix and look at the materials underneath for signs of decomposition. Generally, if you can sink your finger in easily to the second joint, the orchid needs repotting. Signs of decomposed roots -blackening and mushiness or graying and brittleness - are more potent evidence. Different potting media in different conditions deteriorate at different rates. A mix of medium-size bark pieces will last about two years, while finer pieces may break down in half that time. Tree fern may last two to three years; rock doesn't deteriorate at all. Using a mix that combines both decomposing and non-decomposing materials helps lengthen the time between repotting. Timing - the most crucial part of good repottingRepotting gets its reputation for being difficult because people classically repot at the wrong times, and orchids are quick to show their resentment of bad timing. Timing is the most crucial part of good repotting. Orchids go through cycles of growth. New pseudo bulbs, leaves, and roots appear and elongate. After the leading growth or leaf is mature, there is generally a rest period. Afterward, flower spikes and sheaths typically begin, followed by buds and flowers. Most orchids initiate new growth in late winter and spring. Each time an orchid is repotted, its growth is disturbed. Orchids are more forgiving of other potting mistakes if they are at least repotted at the correct time. In general, the best time to repot an orchid is when new growths and new roots are just beginning to form, before those new roots reach even 1/2 inch long. For most plants, this occurs right after flowering. This means that nearly all repotting should take place between February and June. If the plant is left too long after the growth cycle begins before repotting, it must struggle to reestablish itself. If the roots get broken or damaged by repotting, they don't make the branches necessary for a healthy and extensive root system. Energy expended to make replacement root tips is energy taken from flowering. But if plants are repotted at proper times, orchids do flower on schedule the next year. Handling new roots when they are tiny means minimum plant setback. New roots are exceedingly brittle, and there's less chance of breakage if the roots are less than 1 inch long. Repotting at this time gives new roots the longest time to grow before the next repotting disturbance, and they'll be growing into fresh mix. The plant will stay healthier if its roots are well established before it enters the rest period, when no active plant growth is going on. What to do if time is bad, but repotting is a must?Sometimes an orchid desperately needs reporting because the mix is so deteriorated or the plant is badly overgrown. Waiting until the proper cycle to repot may mean that the resulting root damage could hurt the plant more than repotting could. Be as gentle as possible with plants potted out of time, watching them carefully afterward. If you find that the roots are rotten, clean the roots and pot the plant into a very small pot, and wait until the regular repotting time to repot as usual. Don't overdo the watering, but provide as much humidity as possible. If the plant is overgrown but the mix is still acceptable, a procedure called "dropping on" is useful. Remove the plant from its overgrown pot and place it, mix and all, into a larger pot. Then add fresh mix to fill gaps. Dropping on disturbs roots very little and is an acceptable way to repot even at proper times if the mix is still good. Orchids that prefer a somewhat decayed mix (such as Cymbidium) do better being dropped on, with a full reporting only every other time. Another useful trick for overgrown sympodial plants climbing over the side of the pot is to place another same height pot next to it to accommodate the overhanging pseudo bulbs and roots. The second pot should be plastic, so that you can cutaway a V-shaped section of the rim so it will fit better under the overhanging growths. Position the second pot under the new growths and roots hanging over the side of the other pot, and fill it with new mix. Then tape the two side-by-side pots together around both rims, to prevent the new pot from moving. The overgrown parts can establish in the new pot without too much disturbance. When the proper time arrives, the entire plant can be reported into a larger pot, or easily divided, with a natural break at the point between the two pots. Another time you should avoid reporting your orchid is when it is in bud or flower. Wait until flowering is over, because repotting can cause enough trauma to make the flowers or buds drop off. If the orchid has a flower sheath with no buds evident inside, or if the spike is still short and budless, feel free to go ahead if necessary. Newly acquired plants may require reporting if the mix is obviously deteriorated or the plant is overgrown. However, give new plants at least a month to acclimate themselves to their new growing conditions before repotting, to allow recovery from the trauma of a new environment without the added trauma of repotting. Spreading virus, disease, and pestsBecause of all the handling and cutting that goes on during repotting, and because people usually repot more than one plant at a time, the probability of passing virus, disease, and pests between plants is very high. The wisest course of action is simply to assume that every plant is virused. Use plastic disposable gloves, changing them between plants or at least washing them. Don't use your bare hands. Repotting is a sloppy operation; fingers tear away rotten roots or break off old pseudo bulbs, and even with washing, plant pieces can remain under your fingernails, ready to infect. Gloves eliminate many variables, and they protect hands from splinters or possible pathogens in the medium. The other primary source of infection during repotting is the cutting instruments. Never use a cutting instrument on one plant and, then reuse it on another without first sterilizing it between plants. Sterilize tools by using a propane torch flame or by soaking the tools in trisodium phosphate solution. Dipping tools in chlorine or alcohol will not sterilize them enough to kill viruses. An easier solution is to buy packs of single-edged razor blades, and use one for each plant. Blades can be cleaned and oven-baked at 375°F for an hour to sterilize. Reusing potting materialsIf a material is still in good shape, you can reuse it with no problem for the same plant in a different pot. But never transfer a used potting material from one plant to a pot of another orchid. This is sure to transfer pestilences. The best recourse with old organic mix is to resign it to the compost heap. New clay pots have been oven-dried, so presoak them in water for half a day to fill pores. Older clay pots that have been washed and dishwasher-dried also need presoaking. To clean clay pots encrusted with leached salts and algae, soak them in hot water for several days, changing the water a few times. Then scrub with steel wool in warm water with dish detergent added. Adding a little vinegar to the soak water helps loosen salt deposits. In order to kill any virus present on clay and polypropylene pots, pots must be subjected to a temperature of 180°F for 30 minutes. Some high-temperature dishwashers get this high, but most don't. A safer way is to soak the pots overnight in a 9:1 water/bleach solution. Then rinse and soak them in plain water for 15 minutes, rinsing again before using. Baking in a 200°F oven is also possible; polypropylene pots have a melting point of 250°F. Nuts and bolts of repotting
When you're ready to repot, first choose a convenient workspace. A spot near a sink and a trash basket is good enough. If there's no counter space, place a piece of board across the sink. Put lots of layers of newspaper down on the workspace, especially if you are repotting more than a couple of plants at a time. In between each plant, the mess can be bundled up in some of the newspaper and neatly disposed of, leaving a clean layer on which to proceed. Have on hand new or sterilized single-edged razor blades, a box of disposable plastic gloves, a knife, various sizes of clean pots, plant stakes and ties, rhizome clips, and some way to clean the knife in between plants (trisodium phosphate solution or propane flame). A toothbrush is also handy for ridding plants of insect pests. On the floor have a bucket of potting mix soaking in warm water, preferably overnight. Soak each orchid and pot in a bucket of water for a few minutes; this makes it much easier to convince the orchid to leave the pot. Also, the roots will be softer - more pliable and less apt to break - and will release somewhat their often tenacious grip on the inside of the pot. Roots and plant are likewise more pliable when repotted after time in a warm rather than cold environment. Hold one hand over the top of the mix and turn the pot upside down. Some plants slip out easily onto the newspaper layers. If the orchid resists, tap the pot sides and bottom, or gently squeeze a plastic pot in various places. If the orchid really clings to the inside of a plastic pot, take a sharp sterile knife and run it around the inside wall of the pot. If the roots are stubbornly clinging to a clay pot, you may have to break the pot by turning it on its side and tapping gently with a hammer. If bits of clay hang on the roots, don't remove them, as that will break the root. If the orchid is being repotted because of a deteriorated mix rather than overgrowth, you can reuse the same pot. Otherwise, set the used pot away and don't use it for another orchid until it has been sterilized. Taking a look at the rootsNow is an excellent time to pause and take a good look at the potting material, to glean invaluable information about how well it has responded to watering techniques and environment. Even more important, take a look at the roots. Let them be the guide to how well a potting material is working. Live roots are usually white, glistening, sometimes green-tipped, and firm to the touch; these are indications of an excellent mix for the conditions. Dead roots are gray, brown, or black and soft, mushy, or dry to the touch. Decaying roots can be something in between. If the roots are soggy, mushy, or black, the mix is not draining well enough, nor is it aerated enough for the watering technique and environmental conditions. The time between repotting may have been too long. If the center portion of the root ball is dead but roots at the edge of the pot seem fine, then too much water is staying in the mix. Either the potting material itself holds too much water, or you are watering too often. Desiccated gray roots point to an over dry mix. Roots with black tips can be an indication of too many salts, often caused by over fertilizing or softened water, or even snail damage. Remedy the errors by fine-tuning the mix. To make the mix drain better, add materials with less moisture retention, such as charcoal, rocks of some sort, tree fern, coarser bark, perlite, a clay pot. To retain more water, add sphagnum moss, rock wool, finer bark, a plastic pot. While the plant is out of the potClean away all of the old potting material, but try not to break any good roots. The center of the root ball often will be the most decayed. Shake off the mix, pull the root ball gently, and run the orchid under tepid water. Cut away dead roots up to the base of the orchid. To confirm which roots are dead, hold them one at a time and pull gently; if the outer portion slips off easily and a wiry core thread is left, or if the root is brown all the way through the center, the root is dead. Partially decayed roots should also be cut away to a place where fresh tissue starts. If the roots are dead, soft, and mushy, suspect a root-rotting fungus in the mix, and after cutting away rotted parts, treat what's left with powdered sulfur. Try to keep as much of the good root system as possible. If some roots are extremely long and difficult to get into a proper-size pot, trim them. Trim only thick roots that are covered with white velamen. Don't cut away thin, wiry live roots, for these won't form branches like the thick ones can if cut. Trim off dead or yellowed leaves, old flower spikes and sheaths, and dried-up or rotten pseudo bulbs. If an otherwise live-looking pseudo bulb has no leaf, don't remove it, particularly if good roots are attached, for it still stores some reserves of food for the orchid. When cutting away rot, dust the remaining part of the pseudo bulb or the leaf with sulfur fungicide to help keep rot from spreading or recurring. Search the plant for insect infestation such as scale or mealy bug, which can hide on roots, under sheaths on pseudo bulbs, and in the crown of the orchid. A toothpick can be useful in searching down leaf sheaths. If pests are discovered, use a soft toothbrush and tepid water with insecticidal soap to very gently clean the orchid. Preparing the potThe drainage holes must be protected from becoming blocked - particularly important in a clay pot where there is usually only one hole. The most popular arrangement is to cover the bottom of the pots with large pieces of broken pots, polystyrene, stones or other similar material. These are termed crocks. They should be larger than the smallest drainage holes. Arrange the top of the crocks into a slope. This will enable gravity to drain the capillary water that would otherwise be held at the drainage interface between the crocks and the growing medium. Do not put in more crocks just to reduce the volume of the growing medium. Better to put a small inverted pot at the bottom with pieces clipped out of the rim. This will have the benefit of providing an air space in the very area which is the last to dry out. Roots often rot in this area. Contrary to what may be thought, a test will show that extra crocks do not significantly shorten the time taken for water to drain through the pot if the drainage holes are not blocked. Positioning the orchidPositioning depends on the type of growth an orchid makes. Horizontal growers need to be placed so that the back end of the orchid touches the wall of the pot, with the space in front of the newest growth for future spread. If such a plant has symmetrical growth, with no back end apparent, leave the same amount of room all the way around the plant. Monopodial orchids that grow upward should be set right in the center of the pot. Position the orchid in the pot before adding mix so that the rhizome or crown will eventually sit about 1/2 inch below the pot rim. It's not necessary to stuff all the aerial roots back into the pot, but spread out the pot roots in the pot as much as possible. Hold the orchid in place with one hand, and start adding mix. Always stir the mix before using it, for the various ingredients will settle differently over time, depending on weight and volume.
Pourable mixes such as bark-based or tree fern can simply be filled in about a third at a time; tap the pot gently on the work surface with each addition, so that mix can settle without huge gaps. Materials such as sphagnum moss and rock wool don't settle and must be arranged in the pot, so use gloved fingers to push the medium around. Make sure not to pack either one of these too tightly. Osmunda can be packed tightly. The way the "grain" of osmunda or sphagnum moss lies will also affect how much water the medium will hold. The horizontal plant rhizome of a sympodial orchid is part of the stem rather than a root, so it should not be covered by the mix. Allow it to lie half in and half out of the mix. The monopodial basal crown of leaves in plants such as Phalaenopsis should also not be covered but should lie instead just on the mix. Positioning the crown too low, below the mix, will invite rot, and positioning it too far above the mix will cause the orchid to over dry. Once the orchid is potted, it may need stabilizing to prevent wobbling, when new root tips can be damaged or broken off. One way to add steadiness is by placing stones on top of the mix. Even better is to stake the plants upright. Any number of traditional plant stakes are available, wood or metal (more about staking below). Repotting aftercareWatering the orchid right away after repotting does help settle and firm the mix. And while there is no hard evidence as to its real benefit, many orchidists swear by the addition of a few drops of vitamin/hormonal additives such as SuperThrive to the water at this time to help give orchids a good start. If the environment is very humid, simply misting at repotting is fine. If you have a relatively dry situation, water. After that, do not water the orchid thoroughly for several weeks. Instead, give it light misting every day, just to stimulate root growth. Orchids with root systems that have been badly decayed or damaged won't be able to take up much water through the roots, so they are dependent on what the leaves can gather, and light misting helps them immeasurably. The larger pot with more mix will be holding more water than usual anyway, so it's better to keep the orchid on the dry side for a while to avoid rot and to allow cut edges to heal. As the roots get longer, eventually going into the mix, begin regular thorough watering again. It's often beneficial to put the orchid in a slightly more shaded place for the first week after repotting, although opinion differs as to whether this is really necessary. In any event, it probably helps to keep the orchid out of direct sunlight at first, moving it back gradually. Also avoid putting a newly repotted orchid in a cold damp place, especially one with bad air movement. Specimen plants versus divisionThe biggest and most abundant flowers will be found on a plant that is allowed to keep on growing, being moved to a larger and larger pot with each repotting. Another cultural trick for growing a specimen plant is to rotate the pot or mount every few days, so that all sides of the orchid continually receive equal amounts of light. This helps develop growths and flowers allover the orchid, rather than in a single orientation. A primer of pottingEven if you eschew propagation in favor of purchasing full-size orchid plants, you'll eventually be faced with the need to repot some of your collection. Following the flowering season, and before new growth breaks, there is usually a period of 2 to 6 weeks that is optimal for repotting orchids. The orchids are then in their most dormant stage, when the necessary root disturbance will be felt the least. It is also possible to transplant successfully somewhat later, when new growth is 1 to 3 inches long. Orchids growing in 5- to 8-inch containers usually need repotting when the plants have begun to outgrow their containers and the planting medium has started to "break down" and lose its open texture. Larger orchids (in larger containers) should not be disturbed for several years or until the potting material starts to lose texture. The new container you choose should be large enough to allow for 2 years' growth, but no more; this usually means a pot approximately 2 inches wider in diameter. Keep in mind that orchids do best when they are slightly crowded.
Staking orchidsAlthough staking may be no more than a common-sense means of protecting a developing spike of orchid flowers while the plant is in transit, it can also be a happy marriage of art and science that results in a subtly more beautiful presentation at flowering time. Orchid growers use galvanized wire stakes in a variety of configurations that come preformed to suit the habits and various sizes of the most commonly cultivated orchids. Three types offered for sale where orchid plants are sold include:
Another type of stake used by commercial growers is bamboo, which can be thin and reedlike or as thick as a pencil. Sometimes these stakes are inserted only to protect the orchid during shipping. On other occasions, the bamboo cane that comes with a purchased orchid needs no further dressing other than to have utilitarian plastic ties or twist-ties removed and replaced with the more graceful and replaced with the more graceful and organic raffia. Be gentle when tying the orchid to the stake. Use a figure-eight tie, first wrapping the raffia tightly around the stake, then loosely around the orchid stem. Besides wire and bamboo, a third material for staking orchids can be found in most yards, namely twigs from trees and shrubs. Often these can be cut and trimmed so that a "Y" or "U" already present in the branches can gently cradle and hold the orchid spike to show off its beauty to maximum advantage. | |
Back To Top
©2002-2010 herbs2000.com |