Most orchids need to be repotted once every two years. The bark or moss that the orchids are grown in gradually deteriorates. If repotting is not done, the bark or moss become decomposed and packed. Under these conditions, roots are not properly aerated, drainage becomes blocked so there is too much standing moisture, and the plant eventually dies from asphyxiation and root rot. Ideally, orchids should be repotted immediately after flowering.
Tools and Supplies
Selecting a New Pot
Orchids can be grown in any kind of container that has a hole for drainage at the bottom. Because ventilation around the bottom of the pot is vital to the plant~s well being. Water must not be allowed to stand at the bottom of the pot. The same pot may be re-used after the existing decomposed orchid bark has been discarded. However, the used pot must be disinfected with Physan 20. Otherwise, pick a pot that is just slightly larger than the previous one. The pot should be large enough to accommodate for the plant's growth over the next years.
Potting Mix
The potting mix is determined the size and type of orchid to be grown. Phalaenopsis, Cattleya, Dendrobium and Vanda should be grown in Medium Orchid Bark Mix. Paphiopedilum, Miltonia, Odontoglossums and Oncidium need to be potted in Fine Orchid Bark Mix. Disinfect the orchid bark mix with diluted Physan 20, prior to use.
Removal From Pot
Remove the plant from its pot. This should be done in a manner that will cause the least trauma to the roots.
Shake off and remove all of the old bark from the root mass.
Sterilize Tools
To prevent the transmission of bacterial and viral infections, sterilize the tools prior to use. Sterilize the cutting tools with Physan 20 or flame the tool with a blowtorch. Let the sterile tool cool down before using it on the plant.
Trimming
Cut off all dead roots. Dead roots are hollow and soft. Healthy roots are firm and creamy white. The live roots situated outside the pot should be either cut back (Cattleya and sympodial orchids) or retained (Phalaenopsis and monopodial orchids). The live roots located inside the container are preserved.
Cut off any dry inflorescences and dead leaves. Remove any diseased parts from the plant, if possible. Diseased parts are often soft and dark brown or black in color. Paint the wounded area with Alitte.
Repotting
If no division is needed, place the plant to be repotted in a pot that is slight larger than the preceding one.
Dividing
Sterilize the cutting tools with Physan 20 or flame the tool with a blowtorch. Let the sterile tool cool down before using it on the plant.
For blooming size plants, a minimum of 3 to 5 bulbs per division should be kept. The rule of thumb is to make the largest division practical, because the larger plants produce the best and most flowers.
Divide the clump by cutting the rhizome with clippers. Two divisions of the plant are now available.
Rooting Care
Dip the plant in Rootone (Rooting Hormone) or Dip~n Grow to help stimulate new root growth.
Positioning the Plant in the New Pot
Positioning the plant in the new container is not a problem for monopodial orchids such as Phalaenopsis. Simply place the plant in the center of the pot.
Positioning sympodial orchids such as Cattleyas can be a challenge. Position the plant off-center in such a manner that the new growth will develop towards the center of the pot, and the new roots will probe down into the orchid bark. Remember, sympodial orchids need space in front of the bulbs. Otherwise, the plants will escape from the new pot.
Hold on to the plant firmly, while packing the orchid bark mix into the pot. Packing the orchid bark with the use of your hands is less traumatic to the root mass than with the use of a wooden potting stick.
Staking
Use bamboo stakes for support. Stakes are essential for sympodial orchids such as Cattleyas. Place the stakes in a position that will not impede the development of the new growth.
Orchid ties should be soft and reinforced with metal strips. Ties are needed to support the plant. However, ties should not be affixed too tightly, otherwise they will damage the plant as it grows.
Labeling
Newly potted plants should have plant labels with the name of the plant and date that it was repotted.
Care After Repotting
To prevent bacterial and fungal disease, water once with Phyton 27. Phyton 27 is a systemic agent that will protect the plant for the next 90 days.
Place the newly potted plant in a shady location. It is usually best not to water the plant for the next 7 to 10 days. During the second week after repotting, resume a normal watering schedule. After about a month, new roots will appears on the plant. Return the plant to it normal location and begin to reapply Norman's Optimal Orchid Nutrients as recommended.
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