Aerial Roots on Orchids:
7 Important Questions
Aerial roots are not common in other household plants. If you have just come across your first orchid, you might wonder what the projections on the outside of the potting medium are. Aerial roots in orchids can bring up a lot of questions and concerns, which I've tried to answer below. If there are any questions that haven’t been answered, please leave a comment in the box at the end, and I’ll do my best to get back to you.
Can You Cut Aerial Roots?
Never cut aerial roots since they are responsible for providing proper nutrition and adequate hydration for the orchid. Not only do areal roots absorb humidity of water droplets and nutritious micro-elements traveling on wind currents, aerial roots also increase the amount of energy by photosynthesizing.
Again, never cut the aerial root on orchids since this will hinder the amount of nutrients and water absorption your orchid receives.
Orchids never want their roots to be cut, whether they are roots that sink into the potting medium or aerial roots. Never. Just don’t do it. Roots are one way the orchid has to tell it’s in a safe environment and that it will be secure enough to use that enormous amount of energy stored up to produce a flower spike.
You're in luck!
There's a video about this exact content so you don't have to read all 3,000 words below. :)
Where does the name “aerial roots” come from?
The name aerial comes from the Greek prefix, -aer or -aero which refers to oxygen, gas, or just plain air that we breath. If you like word games, you can easily relate to other words where air is related, like aerate (to expose to air circulation) Aerate cake batter…
Another example of -aer is aerobic exercise. In this type of cardio, the cells have sufficient time to perform agas exchange without depleting completely. It’s the anaerobic (lack of oxygen) that makes your muscles hurt the next day with lactic acid.
Anyway, back to orchids…
Why does the orchid grow aerial roots?
What makes orchids have roots that pertain to air are that orchids don’t grow in soil—at least the epiphytes don’t. As seeds, these orchids attached themselves to trees when they were floating through the air. They grew roots that gripped firmly onto the tree bark, about ⅓ of the height of the tree.
This height allowed the orchid to get enough indirect sunlight since the dense canopy of leaves above them made it quite dark at the soil level below. They’d never survive with such low light.
The soil (contrary to popular belief) in the rainforest is quite poor in nutrients. The dark black color mainly comes from charcoal and decomposing elements that have fallen from above.
With this new location, the orchid needed to find a way to survive. By developing aerial roots, the orchid could grasp nutrients that we also floating through the air.
With many flowers nearby, an abundance of nutrients, water, and minerals, the aerial roots had plenty to survive.
What do Aerial Roots Look Like?
You’ve been cultivating your orchid for quite a while and you see a new projection coming form the stem. How do you know this is another aerial root or a flower spike?
The end of aerial roots will be smooth, and to a certain extent, pointed or slightly rounded-tip at the end. A silvery white color will predominate and when you water, it turns green. Yep—all root.
A flower spike with be bumpy at the end, with sharp ends, and possible three or four funny tiny nodules. When you water it, it doesn’t change color, since it already is a greener shade than the root. As it matures, the green color will become more vibrant and harder.
An orchid with prominent aerial roots is the Vanda. These aerial roots are part of the spectacle itself, and many orchid enthusiasts display their Vandas in hanging baskets. The flower spikes on Vandas never disappoint—never.
Do Orchids Like Being Root Bound?
Some of the aerial roots clung to the tree to provide a safe place to hang onto during strong winds and rain storms. But to keep them in a home environment, we can’t hang all the orchids up in hanging baskets or place them on wall mounts.
We need to pot them or mount them.
In the pots, the orchid roots won’t have full access to air. The only thing the pot provides it is the firm surface area to cling to. Orchid roots will grow to the sides of the pot, never concentrating in the middle of the plant, as other household plants do. They prefer the security of attaching their roots to the rough bark-like surface of the pot.
This is why the roots prefer to be placed tightly in a pot, then to have excess room to grow, in bigger, wider pots. Root-bound is not a problem that makes the orchid unhappy. To the contrary – it looses it’s stability and security if it grows in a pot too big for its roots.
Why do Orchids Grow Aerial Roots?
In short, stability. Aerial roots make the safe and secure, signaling it’s safe to send out a flower spike. With unstable roots, the orchid will not send out a flower spike.
As if the orchid followed a pyramid from Maslov’s Hierarchy of Needs, they place safety before propagation of species. Let’s make a crude comparison, so bear with me on this one. Let’s say you just got evicted and have no where to live. With a suitcase in your hand you look for shelter.
Are you really wanting to dress up, kick on some high heels, and go out and dance? I think not. Other things preoccupy your mind. Your own safety is one of them.
Now, let’s say you’ve given up all hope of finding a secure place to stay and now need a new environment to live in. You start looking for other places to live.
Orchids do the same to some extent.
If they don’t find the potting medium secure and can’t relate to it well, then it will send out the last “save me” sign as a beautiful flower spike. This is done so hopefully a bee, butterfly, or other flying critter will pollinate it and its species will go on after it dies. You might think that because your orchid has produced a beautiful flower spike, it’s thriving.
Nope. It’s dying.
Take good care of the roots, and you’ll have a healthy orchid for a long, long time. In common household plants, you can tell the health status by looking at the leaves. For an orchid, verify the roots. If there are no aerial roots, that really isn’t a problem, but if there are many, then your orchid is doing quite well. Keep up the good work.
if you have only aerial roots but he roots inside the potting medium are dying, then you need to change media.
Do Aerial Roots have a Purpose?
Besides providing extra stability, aerial roots aid in photosynthesis. Since the orchid had to give up soil altogether, attaching itself to a tree, and clinging to the bark as tightly as it could, there had to be something that it could do to absorb more energy. The roots adapted to be able to photosynthesize, like the leaves to.
Multitasking done like a pro.
The velamen not only helped the roots attach to the tree, but they also captured the sunlight and with the chlorophyll present in the cells, it helps transform sunlight into energy.
This is why it is so important to keep the aerial roots above ground and use clear, plastic pots at all cost. For more information on this, you can check out this article
about choosing the right pot for your orchid.
Do Aerial Roots Dry Out Faster?
Since the roots are above the potting mix, aerial roots tend to dry out faster than the ones buried inside the pot.
To make sure they don’t dry form low humidity, you can do two things:
(1) spray or mist them every morning, or
(2) cover them with a very, very thin layer of lightly humidified sphagnum moss. The second is a great way for office orchids to survive the air-conditioner and heater, both which suck humidity right out of the air.
How do You Repot Aerial Roots?
Since you have to keep the roots, and make sure they are aerial, what’s the right protocol during repotting time? Do you shove them down in the pot? Or let them be?
If you are just disgusted with the way the roots look, and there are a ton of aerial roots coming out of the top of your pot, then yes you need to repot. One rule though: keep aerial roots in the air and roots that were in the medium, in the medium. Aerial roots are not as malleable like the humidity-soaked roots, sitting in contact with sphagnum moss.
The brittle roots that have been sitting above the potting medium can become more malleable when soaked in lukewarm to warmer water—never hot.
Let the orchid soak.
The majority of the aerial roots can be repotted to fit down under the potting medium when in their new pot, but be warned, they will die off. They have accustomed to being in the air and will not adapt well to the new medium. The still can absorb, but most will die.
Newer roots are better at adapting than older roots are.
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Is there a way to hinder the production of aerial roots?
If aerial roots are just too unsightly for you, then there is a way to hinder their growth. Make a note though that I am totally against this method of hindering aerial roots on orchids. This method will make your orchid suffer and it most likely will not bloom that year.
Remember that the orchid sends out aerial roots to make itself more stable? If you have a massive phalaenopsis (moth orchid or butterfly orchid), for example, with large leaves, and a tiny little root system, the aerial roots want to stabilize the plant—mainly so it won’t fall over.
When it produces the flower spike, the weight of the flowers can make the entire plant topple over, crashing to the ground. To avoid this, the orchid sends out aerial roots as feelers, looking to latch onto anything around it.
To hinder the production of more aerial roots, take away it's stability. Replant the orchid in a pot that is bigger than recommended.
When you give the orchid a bigger potting medium it will want to explore to reach the sides of the pot. Once at the sides, it will cling to them. This will take months, maybe years.
Once the orchid has reached the sides of the pot, it will start to produce more aerial roots. So you have saved a few months without aerial roots.
You have eliminated the production of aerial roots until the lower roots reach the sides of the pot – one year? Two maybe?
It’s a temporary solution, but one that works.
For the orchid, it’s not the best solution though. This will stunt growth and the orchid may not bloom that year. Keep in mind the trade off of having a happy orchid or one that is suffering, looking for stability and security.
Now that you know all aerial roots, it’s time to get your hands dirty. How about mounting orchid? You can check out some of our tutorials on how to repot orchids with sphagnum moss
or how to provide the right humidity for your orchid
until you’re ready to get your start your first terrarium.
If there is any other question about aerial roots that we have not answered in the questions above, please leave us a comment below. We’ll do our best to answer it for you.
If this information was of any help or clarified any doubts you had, please mention so in the comments. We love to interact with other orchid enthusiasts and can share from our experiences.
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