Repotting Orchids

Don’t repot unless you have to! There are two reasons to repot your orchid: poor drainage and overgrowth. If orchid growth extends beyond the edge of the pot, leaving brittle and easily damaged young roots dangling in the air, it’s time to repot. If the growing medium has decomposed, appearing sodden and mushy and no longer draining quickly, it’s time to repot. 

When in doubt, put it off for another year! On the other hand, an orchid that remains in the same pot too long will flower poorly and may even die. Although it isn’t a difficult task, it is different from repotting other kinds of houseplants. The good news is that there is no need to hurry and cover the roots before they dry. Most orchids like their roots exposed to air. So take your time. If you need to take a break or do an errand, just cover the roots with a damp cloth.

When To Repot: In general the best time to repot is late spring and early summer before the onset of vigorous new growth. Particular orchid types such as those with pseudobulbs - the bulbous growths - such as the Cattleya, prefer to be repotted just after new growth but before new roots have begun to elongate. 

If your orchid type lacks pseudobulbs, such as a moth orchid (Phalaenopsis) or a slipper orchid (Paphiopedilum), repot any time, except when blooming. Roots that grow exposed to the air for any length of time will most likely die when packed beneath the bark surface, so try to repot just as new growth is beginning to appear. If you wait too long and your plant is already well into its new season, hold off until after your orchid has bloomed, otherwise you will lose the flowers and you’ll run the risk of killing the plant’s entire new root system. 

Repotting should be done every year-and-a-half to two years, before the potting medium begins to break down into peat and loam. Waiting longer than two years allows the broken-down medium to retain too much moisture, which cuts off air circulation around the roots causing root rot. Follow these general repotting guidelines: Annually for Dendrobium, Miltonia, Paphiopedilum, Phalaenopsis, and their hybrids. Every other year for Cattleya, Dendrobium, Oncidium, Odontoglossum, and their hybrids. Every third year for Vanda and Cymbidium.

Cleanliness: This is the most important precaution, because orchids are particularly susceptible to diseases. Repotting will inevitably involve breaking a few roots and even cutting the plant. You will be coating all these cuts and breaks with medicine as described below. Repot into new or sterilized containers only. 

Sterilize your instruments by placing them in a solution of 1/2 cup bleach to 1 gallon of water for 10-15 minutes and letting them air-dry. Or wipe every surface area of your tools with rubbing alcohol. Or pass them through an intense flame such as a plumber’s torch. Wash your hands before you begin. 

If you are a smoker, Tobacco Mosaic Virus will likely be present on your fingertips so additionally rinse your hands in the bleach and water solution. Thoroughly wipe your work surface with the disinfectant solution you’ve chosen. Repeat wiping the work surface after each plant that you repot.

Pot: Orchids like to be a little tight in their pots. Overly large pots tend to direct orchids into root growth and delay new foliage and blooms for months. Orchids may be potted in plastic, clay, or decorator pots, and the type of pot selected may influence watering frequency. For instance, plants in clay pots will need more frequent watering since they dry faster. Orchid pots must have drain holes. 

Orchid soil in the center of larger pots may remain wet for long periods and kill orchid roots. This can be avoided by placing pieces of clay pots in the bottom of the pot. My favorite way to repot orchids into large pots is to place a small inverted pot in the center of the larger one, with the roots of the plant draped over and around the smaller pot. This provides excellent aeration and drainage. The roots of some orchids, such as Phalaenopsis, carry out photosynthesis. For these plants, clear pots are popular, allowing light to reach the roots.

What You Need

1. Pot. Choose a sterilized pot large enough to sustain at least a year or two of new growth. Remember, if the pot is too large to allow the medium to dry enough between waterings, the roots of your orchid will rot.

2. Soil. Bark, sphagnum, charcoal, perlite, “sponge-rok,” chunk peat, tree fern fibers, oyster shell, coconut husk, or combinations of these depending on your type of orchid, are found at your local garden center. It’s important to use the correct medium for your particular type of orchid. Just look up the name of your orchid online for quick information.

3. Shards. Sanitized clay pot shards, non-biodegradable styrofoam peanuts, or lava rock will cover your pot’s drainage holes without obstructing water from draining quickly.

4. Tools. Sanitized pruning clippers or a sharp knife will be used to divide your plant or trim dead roots.

5. Stake and Ties. A bamboo stake and wire plant tie will hold your newly potted plant steady until its roots grow enough to anchor it.

6. Medicine. Pruning sealer, anti-fungal powder, or antibiotic ointment from your medicine cabinet should be applied in a thin layer to any open cuts on the plant – leaves, stems, or roots – to prevent illness.

Step-By-Step Instructions

1. The Day Before You Repot: Water your orchid thoroughly. A good watering the day before will create pliable roots which are easier to work with and less susceptible to breakage. Wet the medium with boiling water and allow it to soak in a container overnight. The mix will absorb moisture allowing it to be easily placed around the roots of your plant.

2. Un-pot Your Orchid: Prepare your work area by spreading out several sheets of newspaper. Turn the plant upside down over the paper and tap the sides and bottom of the pot to dislodge it. If roots stick to the pot, use a sterilized kitchen knife to loosen them. The plant will not be harmed if you inadvertently damage some roots. Carefully pry the roots apart and shake off as much of the old potting mixture as possible. Don’t worry if some still clings to the roots.

3. Trim: Before repotted, trim the roots. Be sure to sterilize these and all implements used. Remove any dead or damaged roots. Dead roots are mushy and light brown. Healthy roots are firm and white with light-green growing tips. Also cut off any old leafless pseudobulbs. If there is more than one new growth, or "lead," you can divide the plant by cutting through the rhizome. Each division should have at least three pseudobulbs and a new lead.

4. Place Shards: Orchids need excellent drainage, so place a generous layer of broken clay pot or plastic foam peanuts in the bottom of the pot.

5. Add Soil: When placing the plant in the pot, position the older pseudobulbs against one side so that the new lead has room to expand. Pack the dampened mixture around the roots, firming it with your thumbs as you go. Don’t pack the medium – remember orchid roots like aeration. The top of the rhizome should be level with the top of the bark.

6. Aftercare: To keep the plant upright while its new root system is getting established, stake it securely with a loop of twine or use any kind of plant clip that attaches the stem comfortably to the stake. Put the orchid in a lightly shaded location and mist both the plant and the surface of the bark twice daily until new root growth is evident. Once the roots have penetrated the bark, move the plant into brighter light and resume normal watering and fertilizing.