Repotting Orchids

Repotting orchids always seems to send the beginners into a tail-spin, but trust me, it isn't rocket science. You just need to take into consideration what the plant requirements are, and what conditions you can provide. I will attempt to cover off the majority of concerns here by splitting out the considerations into clearly defined categories.

First of all, always keep an assortment of pots available when repotting. You never really know what pot size you will need until you have already unpotted your orchid and cleaned it up. Remember that the proper pot size depends entirely on root-mass, NOT plant size ! The root mass should barely fit comfortably into the new pot, as this will definitely yield the best results with the fewest disappointments. If you try to use a pot that is too large, then you will run into a myriad of problems, so do not try to minimize your work by jumping ahead. The golden rule is that a healthy root system leads to a healthy plant, it is NOT the other way around !

STEP 1 : Decide if you need to repot

You should only repot orchids when you NEED to repot orchids. Many resent the root disturbance that comes with repotting, so it is not a good idea to repot needlessly. The following reasons are the only times you should consider repotting : To clarify the "outgrown" comment, remember that orchids like to be tight in their pots and thrive best when this is the case. In fact, Cattleya alliance plants actually bloom best when they are 1 or 2 growths off the edge of the pot, so repotting them sooner deprives you of a nice display of flowers.

STEP 2 : Unpotting your orchid

Before you embark on repotting your orchid, it is usually easier to unpot the plant if the mix is slightly damp as opposed to being completely dry. Watering your plant the day BEFORE you plan to repot usually makes this step a lot easier. If the plant is in a clay pot, then immerse the whole pot in water the day before (10 to 15 minutes should suffice), as these pots actually absorb a lot of water themselves, and roots often weld themselves to the surfaces making it harder for them to be dislodged easily without excessive damage to the root system.

We find that knocking the outside of the pot on several sides will help to loosen the old potting material. Once loosened, remove the plant from it's pot. Shake off any loose medium first. Now inspect the root system. Remove any large bits of mix that may be attached to the roots, since these will degrade quickly once the plant is repotted. Remove dead roots with sterile tools. Typically you can expect UP TO 1/3 of the roots to be dead or rotten with most plants. If you have more than this, then there is a problem that should be addressed. You may have waited too long to repot, the quality of potting mix was poor, or the original pot size was too large for the root mass. This is also a good time to remove any leaves that are going yellow, or trimming off dead leaf tips. For larger plants, you might also consider removing some of the oldest pseudobulbs if they are very shrivelled and there are plenty of younger pseudobulbs that are in good shape. You can sometimes pot up these back-divisions (back-bulbs) separately, as they can often sprout and give you some new plants to share !

As far as timing is concerned, it is always best to repot orchids when they are in active growth. If there is no sign of growth activity, then the plant will take a much longer time to re-establish itself in the new medium. For most orchids, a good time to repot is in the spring, since growth activity is usually sparked at that time of year, especially for plants growing on a windowsill.

STEP 3 : Decide if you should divide the plant

If your plant is really large, you may want to divide it to get more plants. Do not divide plants into pieces that are smaller then 3 growths, as this will give you the best results. Smaller divisions often languish for a long time before establishing properly, and consequently they are more susceptible to infection and other ailments. Keep in mind that you do not HAVE to divide a large plant unless there is a pressing need to. Larger plants typically produce more new growths off front leads than do smaller plants. This is because larger plants also tend to be stronger plants, so they bloom more frequently and are more resistant to problems than smaller plants are.

STEP 4 : Choose the right pot

There is always a lot of discussion as to whether clay pots are better than plastic pots. We prefer to use plastic pots, since they do not absorb toxic chemicals and pathogens. We only use clay pots in exceptional cases where the plant needs to dry out quickly between waterings, since clay draws moisture out of the mix. The guidelines below are for plastic pots.

Here is our recommended general guidelines for mixes to use dependent on pot size :

Pot Size
(Diameter in inches)
MixNotes
1" -> 2.5"sphagnum mossGenerally the best medium to use, but there are exceptions for species that are poor rooters or prefer mounting.
Frequency : Good quality sphagnum will typically last 1 to 1.5 years before needing replacement.
3" -> 4.5"bark mixes : fine layered over coarseAs the pot size increases, so should the proportion of coarse mix used.
Frequency : Good quality bark mixes will typically last 2 to 3 years before needing replacement.
5" and upCoarse bark mixUnless you have a very dry environment, you typically do not need to layer any finer mix on top of the coarse for these size pots.
Frequency : Good quality bark mixes will typically last 2 to 3 years before needing replacement.
NOTE 1: When potting true epiphytes (tree-dwellers), remember that these are lateral or shallow rooters, so choose pots that are not as deep as they are wide. Most tropical orchids fall into this group.
When potting terrestrial types (ground dwellers), then the reverse is true, since they will want to root deeply, so choose pots that are deeper than they are wide. In choosing a new pot, DO NOT try to compromise ! Piling a bunch of styrofoam peanuts into a pot that is too deep is never a good solution in the long term. If you don't know which rooting type you have, then refer to the appropriate page in the culture groups to find that information.
NOTE 2: There is no mandate that you must use a different pot when repotting. If the current pot is the right size, then you should clean it and re-use it !

Old potting mix is great for adding to your composter. You should NEVER try to reuse it !

STEP 5 : Potting up the plant

We do not recommend the use of styrofoam peanuts or any other foreign materials in the bottom of pots. They allow pockets of mix to remain wetter than the rest of the mix and can accelerate the breakdown of the new mix. We also do not recommend just using straight bark in a mix, as this tends to rot much more quickly than a proper blend of bark, charcoal and perlite. In fact, I call charcoal and perlite my "insurance policy" as charcoal absorbs toxins, keeping the mix "sweet" and perlite preserves air pockets so the roots don't choke as the mix begins to break down. Always use the best quality potting media that you can get your hands on. Sub-standard media or media not specifically targetted for orchids, are an expensive risk, as they usually rot quickly or contain toxins that will affect your plant. Don't learn this lesson the hard way !

Identify which part of your plant is the oldest, as this determines how to best position the plant in it's new pot. If the oldest bit is in the center of the plant, then the plant should be centered in the new pot. If the oldest part is to one side, then push that side right up to the side or corner of the new pot, which allows for the maximum space for new growths to develop. Hold the plant at the right height in the pot as you add fresh potting mix. We prefer to use potting mix dry or only slightly damp (to lessen the amount of dust). Then when you tap the pot as you add mix, it will settle nicely between the roots so you don't have air pockets. When you have finished adding new mix, push it down to secure the plant, and verify that it is at the right depth in the pot. If the plant is unsteady, then secure it with a rhizome clip, or by tying it to a stake until it establishes completely. If the plant is left to wobble in the pot, it will take nearly 3 times as long to re-establish itself, since the wobbling will bruise the new root tips as they emerge.

Roots tend to be brittle and stiff, so when bending them into a pot it is best to be as gentle as possible. If you break a root, then determine if the break is right through the actual root and not just the outside covering (velumen). If the break is right through the wiry bit in the middle of the root, then the actual root itself is broken and should be removed. However, if the wiry bit in the middle of root is still intact, then the root is still viable and should be kept. If you have damaged one or more roots in this manner, then the following comments about aerial roots apply, and this treatment will allow the root to heal properly.

If you have aerial roots, they too can be put into the pot now. If their numbers are high, then just water on the shy side for the first 2 months, to allow the cells in these aerial roots to adjust to being buried. Otherwise you can just water normally. This guideline also applies if you have transitioned the plant into a different type of potting mix than it was in before. You have to allow the plant to adjust whenever such a drastic change is made.

STEP 6 : Update your records

You should now record the new potting date somewhere. We recommend using the back of the plant tag for this purpose. Just jot down the month and year. This will help you to determine when you should consider repotting your orchid the next time.

Congratulations, you have now successfully and properly repotted your orchid !


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