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Repotting Orchids

Repotting orchids is critical to maintaining and flowering them but this needs to be done differently than other house plants. Once you accept the fact that orchids are different, then the care of orchids becomes simple. Regular orchid repotting will ensure a good root system and lots of flowers.

Orchid repotting - coconut husk, by Robert Pavlis

Orchid repotting – coconut husk, by Robert Pavlis

Repotting Orchids – When?

When should you repot an orchid? The golden rule is every two years – see the next section for some exceptions. If it is done every two years and you do not over water, your orchid will always have a good root system. It is important to do it regularly because the orchid media – the stuff in the pot – breaks down and becomes too fine. It then holds too much water and not enough air. The media also starts to accumulate salts which are deadly to orchids. A repotting every two years solves both problems.

What about repotting a newly purchased orchid? You don’t know how long it has been in the pot. If you bought it from an orchid grower, the repotting date will be on the plant label. If not, ask them when it was repotted last. If they don’t know you might thick twice about buying orchids from them.

Should you repot when it is in flower? It would be best to wait until flowering is over, even if you have to extend the 2 year rule by a few months. Repotting orchids at 2 1/2 years is OK. But if you need to repot for some emergency reason, it will not kill the plant, or shorten the flowering period. Just handle the plant carefully so you don’t knock off any blooms or buds.

Repoting Orchids Sooner

There are times when you should not follow the above 2 year rule.

Orchids sold in grocery stores and big box chains are usually imported into the country bare root and repotted just before they are sold. So in theory you have 2 years from the purchase date before it needs to be repotted. The problem is that many such plants are potted in sphagnum moss, and this material is real hard to water correctly and it breaks down quickly. If it is in sphagnum, report as soon as the orchid stops flowering.

Recently I bought an orchid and when I got it home I realized the pot had no drainage hole! This orchid was doomed to die unless I watered it very carefully. I immediately repotted it into a pot with holes – even though it was in full flower.

The other exception for the two year rule is when your roots look like the picture below. If you have a lot of rotting roots in the pot it is a clear sign that you have been over watering, or that the potting media is no longer drying out fast enough. In either case I suggest repotting immediately to try and save the plant.

Selecting the Right Potting Media

The potting media is the stuff in the pot. It is not soil and soil should never be added to an orchid pot.

Orchids in the wild live in trees. Their roots grow in the grooves of bark and are completely exposed to the air. They get very little fertilizer this way and only get watered when it rains. Orchid roots have been growing outside of soil for millions of years and it is important to treat them the same way in the home.

Since you probably don’t have a tree in your living room, you can simulate the tree by using pieces of bark in a pot. Bark works well and has been used for many years. Unfortunately, good quality bark is now very expensive. Thankfully, orchid growers have found a good substitute – coconut husk – see the picture above. Coconut husk is the outer shell that is left over after processing the coconuts. It holds a lot of air and water which is exactly what orchid roots like. It also breaks down very slowly so you don’t have to repot more than every 2 years. And it is also relatively inexpensive.

Many other media have been used for orchids and some web site promote them, but I suggest you stick to coconut husk. When you buy the media, make sure the chunks are about the size of your baby finger nail. Larger is OK, but much smaller is too fine and will not hold enough air.

A new trend in orchid media has started in the last few years which is a problem. Manufacturers are packaging the media in white, opaque plastic bags so you can’t see what you are getting. Don’t buy these. You want a clear bag so you can see the contents and confirm the size of the chunks.

If the mix has a small amount of perlite or charcoal in it, that is OK too, but you don’t need these things. I have been using straight coconut husk for 10 years now and it works great on its own.

Cleaning the Orchid

To start repotting, take the orchid out of the pot. Shake off all of the old media and don’t reuse it for orchids. It can be added to the garden or to the soil of other house plants, but don’t use it for orchids. You will probably find that some of the material is stuck to the roots. Try to gently pry it off. Don’t pull so hard that you damage the root, but try to get most of it off the plant.

Examine the roots. If the plant has been growing properly, the roots should be a white or green color, and they should be solid and roundish. Healthy roots will have a green tip where it is growing. Keep all of these good roots.

Repotting orchids before root rot sets in

Repotting orchids before root rot sets in

Look for dead and dying roots. All orchids will have some old roots that are dying, but most should be healthy. If the root is black, or mushy it is dead. If is white, flat and has no substance, it is dead. If you can see wrinkles, it is probably dying. All of the dead and dying roots should be removed.

In the above picture the green arrow shows a healthy root – it is nice and yellowish-green. Leave these roots alone.

The two purple arrows show two roots that are dying. They are white in color but they are getting soft and mushy. If you feel them they are mostly flat and empty. Black spots and shrinkage lines are starting to develop on the roots. The one on the right has a black tip which indicates it is no longer growing. These should be removed by cutting them all the way back to the plant.

The black arrow shows a root where the back portion, the green part, is healthy. The front part of the root is dying – it is turning black. Cut it back to the green part of the root. There is a good chance that it will start to grow again at the point of the cut.

If a good root breaks, just leave it. The root is the thin part inside and is probably not damaged. Read more about velamen in Orchid Care.

Dead and dying roots will just rot in the pot and may cause problems for the good roots. No matter how cruel this process might seem – cut the bad roots off the plant. they provide no benefit to the plant.

Look for Scale and Mealybugs

While you have the plant in your hand, look under the leaves, and in any cracks between leaves. This is where scale and mealybugs start to grow. If you find some, spray the plant with rubbing alcohol before you repot it.

Select the Right Pot

Traditionally, orchid growers have used clay pots and these do have some advantage in the greenhouse, but in the home it is best to use standard plastic pots. The best ones are the ones with holes in the bottom and along the side, near the bottom. Never use a pot without drainage holes and more holes is better.

If the orchid roots were very crowded in the old pot, move up to a larger pot by 2 inches, but no more that. You will never kill an orchid in a pot that is too small, but you might if the pot is too big because a large pot stays wet longer.

Repot the Orchid

With one hand hold the orchid at the right height in the pot and with the other hand fill in the spaces between the roots with the potting media. Use a gentle pressure to pack it in. This packing will help hold the plant in place.

What is the right height for the orchid? When you are done, the potting media should go up to where the newest root is coming out of the plant, but not much above that. On a palaenopsis, the leaves should not be covered. The video below shows this well.

Some times the orchid will be a little loose after repotting, until it make new roots. You can add a rhizome clip to the pot as shown in this video.

Watering

Your orchid is now potted. If it has a label write the repot date on it, so you will know when it needs to be repotted  again – two years from now.

The last step is to water the orchid as explained in Orchid Care.

Since the potting media is new it will dry out faster than the previous old material. Keep an eye on this. You might have to water more often than you expect for the first couple of months.

Blooming Orchids

Now that the orchid is repotted you will want it to bloom again. To find out how to do that have a lot at Blooming Orchids – my next post on orchids.

References:

  1. Photo sources – second photo; Scot Nelson

 

Robert Pavlis
Editor of GardenFundamentals.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Fundamentals an educational site that helps you understand your garden better.

5 Responses to 'Repotting Orchids'

  1. Deborah Schubert says:

    I have roots that are exposed and not in potting media. I’ve been told these are referred to as air roots and NOT to cover them with media when re-potting. Also that the new potting media should be soaked in water for 1 hr then drained in colander for 1 hr. Now I’m really confused after reading your post. Please help.

    • It is true that the roots growing outside of the pot are air roots – but so are the ones growing in the pot. Orchids growing in proper potting media only have air roots. when I report, I try to get most roots, including the ones in the air, into the pot. they get more moisture and nutrients there.

      There is no harm in soaking the media first – but it is not necessary. In fact some people recommend not watering for a week or two after repotting. the reason for this is so that any damage to the roots can heal before they are made wet. Wet media will only enhance the growth of fungus. I report and water right away, most for convenience.

  2. Emily says:

    My orchids leaves have become wrinkled, limp and dark green, also starting to go yellow on the edges; is it dying? Should I repot now or try and get it healthy again first?

  3. Gale Norman says:

    Love all your post. I learn so much from them. Thank you.

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