Cultivating Orchids & Crafting Terrariums

How to Repot an Orchid with Air Roots: 5 Tips for Success

Can air roots be potted in the orchid potting medium or should they be left alone? Determining what to do with orchid air roots, most often called aerial roots, is challenging for most orchid growers. Air roots on orchids aid the plant's health and should never be cut. Yet what about repotting? Should you leave them spilling out over the sides of the pot?

To repot an orchid with air roots, 1) soak the entire orchid for 10 to 30 minutes below the stem or rhizome before the repotting process to make the air roots malleable. 2) Determine whether or not each aerial root needs to be inserted in the pot or remain on the outside. 3) Carefully manage the air root while arranging them either inside or outside the pot. 4) Fill the pot with potting medium up to the lower part of the stem or to the rhizome.


The hardest part int his tutorial is the second step: determining which air root needs to be potted or not.
Orchid Aerial Roots
Image Credit: © 2020 Orchideria.  All Rights Reserved. 
When It Comes to Repotting, What to do With The Aerial Roots on My Cattleya Orchid?
In this article, I’ll focus on the aerial roots of the orchid and their unique place in the pot during the repotting process. If you want more information on a basic repotting tutorial, read this article where I go over a step by step guide of how to repot. I did mention some information about aerial roots, but felt that it needed a full guide of its own to better explain the decision-making process.

Most tutorials about repotting air roots will present one unique answer: don’t repot aerial roots or repot air roots, but never explain the other side or other opinions on the subject. I don’t believe that this approach will help you come to a good decision on what to do with your aerial roots, since the information is biased. Every one has different and unique growing conditions.

The water and fertilizer you use is unique and special to your environment. The levels of sun, calcium, magnesium, the temperature, the air flow—all these variables will interfere with how you grow orchids. I can’t assume what works for me will automatically work for you.

In this article, I will present several unique positions and go over the reason (or not) in each one and in the end, I’ll present my answer.

So let’s div into to this tutorial: How to Repot an Orchid with Aerial Roots.

1) The Number or Air Roots Do NOT Determine the Right Time to Repot an Orchid

Air roots in abundance to not mean it’s the right time to repot. It also doesn’t mean that the pot is root bound. It’s a common mistake to think that because the roots are growing outside the pot an into the air, there is no more room inside the pot for them to grow. This is not true. There can be plenty of room inside the pot to grow yet your orchid will still produce aerial roots.

This happens because orchids in nature produce roots in all directions. They will attach to trees yet be exposed to wind currents, rain, animal droppings, leaf litter that falls from decays overhead leaves, and sunlight.

If you want to read more about aerial roots in and of themselves, this article I wrote about aerial roots is a good start. In essence, they are the made in the same exact way as the roots that dive into the depths of your potting medium. There is no difference in cell structure.

Yet the roots that do go down into the potting medium will adapt over time to better absorb the minerals, elements, compounds and all the nutrition that they can in the environment they are in.  The potting medium roots are not chemically structured differently as aerial roots, yet they have adapted to better absorb nutrients where they are.

Once they have spent some time adapting in their environment, they have a hard time re-adapting to a different place. That is why the orchid struggles so much if you keep changing environments on it, such as changing it from sphagnum moss to orchid bark, to semi hydroponics to full water culture then back to orchid bark. Keep your orchid in one type of potting medium and don’t change it.

A mature aerial root will have better acclimated to its surroundings, and will have better adapted to not receiving that much water or humidity. Inside the potting medium, the water will be contact with the potting medium roots, which increased the humidity considerably.

To determine whether or not it’s time to repot, you need to keep a diary or journal of when the last time you repotted. If you are using pure sphagnum moss, you’ll need to repot almost yearly. Sphagnum moss degrades extremely fast. Orchid bark can last from 2 to 3 years. Charcoal lasts a lot longer.

The only reason you need to repot is strictly because of the degrading medium inside your pot. The organic materials break down over time and this invites bacteria and fungus. The pH will slowly lower, turning more acidic. Even though most epythitic orchids prefer to have a lower acidity of around 5.5 to 6.5, the pH in a degrading potting medium can go down to about 3 or 4. This will kill your orchid in less than a year.

If you are worried about your orchid being root bound, you don’t need to be. In fact, orchids like to be roots bound. In nature they use the roots to stabilize themselves inside the open grooves in the tree bark. They attach themselves so tightly that torrential rains don’t bring them down. This is the kind of attachment they like to have inside a pot.

The roots will grow to the surface of the pot (surface not as in the top but as in the sides of the pot) and firmly attach to them. Then they will circle around the outer rim of the pot. If you want to know more about rootbound orchids, in this article I wrote you can read about why this is important to the orchid.

2) Soak All the Roots—Aerial Roots Included—Before any Orchid Repot

Soaking the orchid pot is already a natural process before any repot because this will fill the velamen with water, making the roots more malleable. It also releases (to some extent) the attachments that the roots have with its surroundings.

If the roots have strongly attached to the sides of the pot, or to the orchid bark, charcoal, or the worst in my opinion—terracotta pots—then the soaking will make the roots let go of the tight grip.

We tend to soak the orchid up to the rhizome (if a sympodial orchid like a Cattleya) or up to the bottom of the stem (if a monopodial orchid, like a Phalaenopsis). Just don’t forget to soak the aerial roots too. Even if you haven’t decided they are not going to be inside the pot or not, they need to be soaked.

The ends of root tips are extremely sensitive, and even the manipulation (as in handling during the repotting process) can hurt them. I have several Cattleya root tips that are no longer green but have wilted at the very tips, stunting their future growth.

Make sure all the aerial roots are hydrated before any repot. Potting medium is king of hard to get packed in the pot where it’s secure yet air can circulate freely, and the all the root tips suffer a tad bit from this repotting process.

3) Determine Which Air Roots Will Be Repotted Inside the Medium

Here is to the controversial part of the tutorial. Some orchid growers (most actually) will demand that all aerial roots continue on the outside of the pot. This is the most prevalent opinion amongst orchid growers. Very few will say that they repot the aerial roots inside the potting medium and have never had any problems with this type of procedure. Let’s look at each one in detail.

3A) Leaving the Aerial Roots on the Outside During the Repot

Let’s look at the most prevalent opinion first: if aerial, leave aerial. As I mentioned before, the structure of the aerial root is not any different than a root that has been acclimated to growing inside the pot. Yet, it has adapted to being in an environment with less humidity, therefor can withstand the lower RH (relative humidity) in the area where it’s being cultivated.

When the root that has been out in the air suddenly loses its supply of fresh air (air flow inside the pot is less) and its supply of sun (obviously the light levels inside the pot are lower), the root will naturally decline.

An older root is not as “teachable” as a new root, and will not have the same ability to quickly adapt to its new climate. The natural reaction is that this root will rot.

In essence, you are placing a rotting root inside your pot, because that is what will happen. It will die. Dying orchid material draws in bacteria and the pH is disturbed. The toxin levels rise in your pot. The whole idea of repotting was to provide a new, fresh, healthy potting medium, and in essence, you traded six for half a dozen.

The only tricky part in this method is remembering which roots where aerial and which were not. I’ve done my share of removing the potting medium, scrubbing down the plant and returning with all the roots plump, green, luscious, and extremely similar.

Which roots was the aerial one? I have no idea… So all in the pot they go.

It’s easy to determine which are the potting roots before you took them out of the pot, but those select few that hung over the pot—which were they? Keep an eye on which root was the aerial root and as you fill the pot with potting medium, remember to keep it on the outside.

3B) Repot the Aerial Roots Inside the Potting Medium

The other opinion about repotting aerial roots brings a lot more criticism—bury the roots. All of them. The reasoning behind this is that eventually all roots will die. Yes, that is true—all roots will die in time.

Yet orchid growers who go by this reasoning declare that the roots that are young will adapt to the new potting material and if you keep the roots near the outside of the pot where they still get sunlight and adequate airflow, they will better adapt to the pot. This is also true. Let’s look at each in more depth.

When the roots are new, aerial or not, they have not had time to know that the “status quo” is of their environment. Once they are established, they have a better sense of what should be expected. If those conditions are not met, they suffer.

After the initial soaking of the aerial roots, you can bend them to point down toward the pot.

The roots are flexible and malleable, and will work well with you. The younger the roots the better, too. You can bend these roots to reach the top of the pot and keep them on the outer side of the pot.

3C) When to Never Bury an Aerial Root

There are a few exceptions to the rule above, where all roots get placed back into the potting medium. Roots can sometimes grow from in between leaves. It’s a big deception at first, because I always think it’s a flower spike, only to sadly find out it’s another root.

Not all roots grow from the bottom of the stem. When these aerial roots grow, sprouting out from a higher pint on the orchid stem, it’s better to leave them in the air. They can find their way to the potting medium, but it will be some time before they outgrow the length of the leaf they are covering and at that point, it’s more likely they keep growing out not down.

Another point to consider is if the air root is an older root. Roots do not live indefinitely and will die off much sooner than your orchid will. The same is true about leaves. Leaves come and go.

If the air root on your orchid is much older and you know that much younger roots will come, it’s best to leave it in the air. You do not want to add material to your potting media that you know will die out in a short period of time.

This also goes back to the beginning of the article, where the younger roots would be more adaptable to experience a change in their medium, where the older roots would suffer more. It’s its that old that it will die off in a couple months, it will not adapt to the potting medium change well at all. In fact, it is more prone to not absorb anything at all. If it had been left out in the air, it still could contribute to the nourishment of your orchid.
Yellow Roots on Orchids
The aerial root before soaking will be lighter gray, but when watered, this color is the same as the other roots. In this picture above, the aerial root to the right is longer than the rest.
Since it is not an old root nearing death, it can either be repotted in the potting medium or left out to continue being an aerial root.

4) Never Trim or Cut Air Roots When Repotting Your Orchid

One item to note carefully is that you should never cut the air roots when trimming your orchid. Pruning orchids has never been a concept in my book; I leave them alone. Air roots are contributing to the overall nourishment of your orchid, and depending on the state of your potting medium, it might be the only thing that is providing nutrition.

Sometimes the roots inside your pot are in such a bad shape, that the aerial roots are the only ones that are healthy. Sadly, we only find this out when we repot or when the leaves and stem start to wilt.

I identified 13 signs that indicate your orchid is healthy (you can read about them in this article) so that you don’t have to go through the displeasure of repotting to find out there are no good roots. Careful observation of these signs can save you a bundle of headache in the future.

I only cut roots that have been inside the potting medium because they are presenting some kind of harm to my orchid. This could mean that they are mushy, brown, have black rot on them, are full or fungus, have some kind of bacterial growth, or present overall death. These roots should be cut off. Yet these problems are due to 2 reasons: watering too frequently and watering too much (quantity).

With aerial roots, neither of these problems exist.

The roots aren’t going to be soaked in water and even if you water them too frequently, the air around them will quickly provide dryness. This eliminates all the reasons to have problems with aerial roots. The only problems that aerial roots have are when they are buried in the potting medium and do not have proper air circulation, sunlight, and are in constant contact with humidity (water).

5) How do I Repot an Orchid with Multiple Aerial Roots?

…and it’s confession time. I am a bit of a scatter brain and when it comes to aerial roots. I have a tendency to forget which roots were aerial and which weren’t. After soaking, they all look somewhat the same. This leaves to the alternative of always burying the roots, aerial or not, unless I know for a fact they are pointing straight up or are so high up on the stem I know they aren’t aerial.

This does present a myriad of problems.

I have never had success with burying aerial roots and would prefer to keep them out of the pot at all possible. Yet, I get so tied up in the potting process and am so content while practicing my hobby that I honestly don’t remember to keep them on the outside.

They die. All of them.

I need to keep some sticky notes or something… So I try to follow the first advice, to keep them on the outside of the pot. They grow better, continue to stay healthy, and are adapted to that climate. So why try to force them to change?

6) How to Determine What Advice to Follow For Repotting Aerial Roots: Inside or Outside the Pot?

This is the Bonus Tip. I had mentioned in the title “5 Important tips for Repotting an Orchid with Aerial Roots”, but I think this is an important step, too.

If your house is dry, and you cultivate your orchids indoors like I do, the relative humidity is going to be low. In most houses, relative humidity ranges from 27 to 33% year-round. This happens because we tend to keep humidity sucking appliances on, like air-conditioners and central air heaters.

Orchids like to have a considerable amount of humidity around them, and Phalaenopsis start at 40%. Other orchids like an even higher ratio of water droplets in the environment.

Even with a humidifier, the orchid aerial roots are the first to take the hit. They will suffer with the lower humidity and most the time, will shrivel and become crunchy. The orchid will sense over time that this is not the best and will prefer to send the roots down in to the potting medium where humidity is better offered.

If you have a greenhouse, where humidity can be considerably higher, that this will not affect the production of aerial roots. In fact, it will actually promote and stimulate aerial roots. Since in nature aerial roots grow over the bark in all directions, the orchid would prefer to imitate this style of growth.

That will be the main variable in determining whether or not to bury the aerial root inside your potting medium or not. How much humidity does your environment provide? Do you have a humidifier on the orchid all day long?

If you don’t have a humidifier, read this article where I detailed the decision-making process of when I bought my humidifier, the types of humidifiers, and what will work best for your needs in your environment.

Forcing an aerial root to live in an environment without adequate humidity is a death sentence. It’s better if this root could have a chance at survival inside the more humid pot.
I hope this article has been helpful, and if it has, please comment below. Just so you don’t have go back and search for the side-articles I mentioned in this tutorial below are the titles of the articles:

Aerial Roots: 7 Important Questions and Answers
Root bound orchids: 5 Important things You need to Know
Best Humidifiers for Orchid Care: Product Reviews
How to Repot an Orchid: Complete Guide & Secret Strategies
13 Foolproof Signs of a Healthy Orchid

If you have any questions, please comment below, too. It's always good to compare ideas and suggest new opinions when it comes to orchid care.

Happy Cultivating!
Signature Amanda Matthews
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ABOUT ME 
Amanda June Matthews at Orchideria
Hi, there! I'm Amanda Matthews.

I write all the tutorials on Orchideria so unfortunately, I can't blame anyone else for all the spelling mistakes.   :)

By profession, I'm a theologian, author, and seminary professor, yet I  spend my free time enjoying nature hikes, building terrariums, and cultivating orchids. I also love to mountain bike on trails, dance, and play with my dog, Max.

When I'm not working on the next chapter of my book or online course, I'm exploring a new campsite to venture out into nature. Pitching a tent for the weekend with my two children while I fire up a barbecue is the best way to live.

Click here to go to my Author Page to check out my heart-wrenching memoir.

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