Repotting orchids is not difficult, but it seems to be one of the most dreaded tasks for beginners. Many nurseries even offer repotting services, so you don't have to deal with it if you don't feel like it. But if your collection is growing and you want to learn to do it by yourself, repotting is not exactly rocket science and can be perfected with some research and practice. After you read this page (plus a few related pages linked below), you will be all set to go.
Repotting Orchids — Why?
Most orchids don't like to be disturbed. Every time you mess with the roots, even the most vigorous orchid needs time and energy to recuperate. Imagine if you are an orchid, you wouldn't want to be pulled out of a pot and get a few roots broken for no reason! So I don't recommend repotting just because you have too much time on your hands. However, if you encounter one of the situations below, then repotting orchids becomes essential.
- The orchid is outgrowing its pot.
- You want to divide your orchid.
- The potting medium deteriorates and gets black and mushy.
- There is a large infestation of pests in the potting medium.
- You suspect the roots of your orchid are rotting.
- Fertilizer builds up to the point that the medium is covered with white dust or the leaf tips of the orchid are burnt.
Remember that you don't need to repot just because the roots are growing out of the pot. Most orchids grow on trees in the wild and their roots are used to wandering everywhere. It's natural for them to venture out of the pot. And don't trim those roots either. These roots are functional and they help your plant become strong.
Repotting Orchids — Timing
Unless the repotting is urgent and the orchid will be severely harmed without immediate action (rotting medium, pests, massive dead roots, fertilizer build-up), it's best to wait until the perfect time to repot. Perfect time means when your orchid is active and has sufficient strength to reestablish itself quickly from the somewhat traumatic experience.
- The ideal time to repot orchids is when new growth is emerging, when new roots are evident as little bumps on the underside of the growth. If the roots are already too long (a quarter to six inches long), then it becomes impossible not to break the roots when handling the plant. For most orchids, usually the new growths come out after the blooms fade.
- It's best not to repot when the orchid is in bloom. The orchid is using its energy to sustain the flower. Repotting might cut the lives of the flowers short.
- However, some orchids may bloom and send out new growths at the same time. In that case, you should wait until the flowers are gone and the roots of the new growth are six inches or longer. At this stage, if the roots are injured during repotting, they have the ability to branch out new root tips along the length of the root.
- For most orchids repotting only needs to be done once every year or two.
If a plant is disturbed after the growing season is over, it may take substantially longer period to reestablish itself.
Repotting Orchids — Preparation
To ensure a smooth potting experience, there are a few things you should gather before you start.
- Soak your potting medium in water overnight. New bark doesn't absorb water as readily as older bark, so soaking will ensure your orchid will have enough water after it's repotted. If you are using other potting medium such as coconut husk chips, sphagnum moss, clay pebbles, charcoal and perlite, then wet them thoroughly or soak them for an hour.
- Decide the right pot size for your plant. Orchids like to be very snug. The pot should only be big enough to accommodate one to two years of growth. If your orchid is not outgrowing its pot, you can even reuse the original pot.
- Sterilize all your equipment, which include a pair of scissors to cut dead roots as well as a stake and zip tie to stabilize the orchid in the mix. You can use a bleach solution to sterilize. (Rinse thoroughly afterward!) I also use a butane torch (found in hardware stores) to sterilize my scissors before working on the next orchid. The reason for this is to prevent spreading disease from one plant to another.
- Get a plastic label/tag so that you can write down the name of the orchid and the repotting date.
- For each orchid you will work on, get a pair of latex gloves (or latex alternative if you are allergic).
- Prepare some cinnamon (yes, the kind you use to cook with, as in cinnamon buns) or sulfur. You will need them to dust the roots after they are cut to disinfect them.
- Soak your orchid in a bucket of water for half an hour or so to loosen the potting medium and make the roots more flexible.
OK, let the "repotting orchids" party begin!
- Wear your gloves.
- Tap the pot on its side. Hold the pot upside down and gently pull the plant out of the pot.
- If the roots are clinging to the outside of the pot, cut them at the rim.
- Remove as much potting material as possible. If the root ball is very tight, gently massage it to loose it up. Orchids like backrubs too.
- Trim off the dead roots. Dead roots are black or dark brown, mushy and hollow. If you use your fingers to gently squeeze and pull, the "skin" will come right off and the only thing remain is a "wire".
- If there are old and shrivel "back bulbs", you can also cut them off. But don't cut the plump ones off even if they are leafless; they are still providing energy to your plant.
- If you decide to divide your plant, you can cut between the pseudobulbs, but make sure that each division has at least three or four bulbs.
- Rinse the plant under the faucet to remove more potting medium.
- Dust the cut ends of the roots with cinnamon or sulfur.
- Fill some potting mix in the bottom of the pot.
- If you have a sympodial orchid (pseudobulbs are next to one another) such as Cattleya, Dendrobium and Cymbidium, then position the end psuedobulb by the edge of the pot, so that the new growth will have space to grow.
- If you have a monopodial orchid (grows vertically) such as Phalaenopsis and Paphiopedilum, then position the orchid in the middle of the pot.
- Fill the potting mix around and up to the base of your orchid. Tap the side of the pot to settle the mix.
- Put the stake into the potting mix and use the zip tie to hold the stake and one mature growth.
- Use the old label or, if divisions are created, copy the orchid name from the old tag to the new tags. Also write down the date of repotting for future reference.
Repotting Orchids — After Care
- New potting material doesn't absorb as much water, so increase watering frequency for the first couple of months.
- You can use several drops of Superthrive in your water to help your plant ease into the new environment.
- Put your orchids in a slightly more humid and slightly less brightly lit place for the first week. Then gradually put them back into the normal environment.