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Cuttings do not need an aerial root to successfully root.
HOWEVER (it can never just be an easy answer, can it?)
I’ve carried out several propagation experiments over the past few months and the aerial root/no aerial root thing definitely does impact on the way cuttings root and the speed at which those roots emerge.
Overall, I don’t think that cuttings with aerial roots root better than those without…they just root differently.
Plants vary a lot, this is just what I’ve observed from my own propagations. If you’ve had different results leave me a comment or send me a DM on Instagram – the more data we have, the better.
Do you need an aerial root to propagate?
No. Aerial root growth is dependent on several factors, the most important being humidity. The next probably being genetics.
If you’ve read any of my articles on the climbing vines growing in my terrarium, you’ll know what a MASSIVE impact growing plants in high humidity has on their aerial roots.
But genetics also play a massive role. My Monstera Thai Constellation diligently grows a new aerial root after each and every new leaf, which is super helpful to me because it staves off needing to put her on a moss pole.
Another Monstera just grows aerial roots, no leaves, another does the opposite. As long as they’re happy, I’m happy.
There are a couple of benefits to taking cuttings that have an aerial root:
- You know you’ve got a node. No need to worry that it’s incapable of rooting because you cut in the wrong place. If you have an aerial root, you should have at least some node cells
- The plant already has root-adjacent tissue formed
Aerial roots and subterranean roots aren’t the same, but aerial roots can transform into underground roots. It’s a little bit like rooting a top cutting versus a mid-cutting*, but with aerial roots rather than axillary buds.
Sometimes, a plant can grow water roots directly from the ends of the aerial roots, like this:
If it doesn’t have an aerial root, it’ll have to grow them from scratch, and they’ll emerge out of the node, like this:
In my experience, the faster you can get a cutting to root, the more likely it is that the root will come from the aerial roots. If your cutting doesn’t have an aerial root, it won’t root as faster as one that does. I’ll go into more detail about this later on, because faster isn’t always best.
*Legend has it that top cuttings are better than mid cuttings because the top cutting has an activated axillary bud, so the plant doesn’t have to go to the extra effort of activating/growing a new one.
Will a brown aerial root help with rooting cuttings?
If you don’t have particularly high humidity or the aerial root isn’t being used by the plant, they tend to go brown and look a bit like a dead stick.
They’re lying to you.
Unless the aerial root is disintegrating, it’s probably still alive, it’s just covered itself in corking for a bit of added protection from the elements. You can actually peel it off, though you shouldn’t because it’s there for a reason.
Sometimes (again for *reasons*) plants decide to randomly start pursuing growth in an aerial root it had previously abandoned. My big Monstera has *just* decided to start growing this one again:
You can just see that the very tip of the root has some green coming through.
(This is the Monstera that likes growing aerial roots but was working on a new one before going back to this one. How about some leaves??)
Do you put aerial roots in water when propagating?
Yes, even, and you may think I’m mad for saying this if they’ve snapped (but are still slightly attached to the cutting).
This Rhapidphora cutting is sporting a lovely new growth point but zero (0) roots. I can only assume that some minute amount of nutrients/water is getting to the node using that dried-up pathetic excuse for a root.
I know that looks like green on the root, but it’s algae. The whole thing is white and brittle, plus it’s snapped in half, but the outer casing is keeping it together.
There’s another node further down that I’m trying to root, but so far, NOTHING. Too busy growing that freaking leaf.
Babe, I love you, but in the immortal words of Ron Weasley, you have GOT to sort out your priorities.
This is the plant that propagated itself by severing its own stem under a grow light. Metal.
Will having an aerial root make cuttings root faster?
There are two things you can do that MASSIVELY speed up the rate at which cuttings root, without having to create a fancy setup with heat mats and bubblers and grow mats etc.
When I propagated using these two methods I got roots within the week.
But that isn’t the whole story. The nutrient water article I linked to above goes into more detail, but in short, if your cutting has an aerial root, it has the potential to root a lot faster than one that doesn’t.
But speed ain’t everything. A cutting I rooted in soil (a very slow-going method when it comes to rooting) took AGES to root but because it was in the terrarium, it grew roots, and then was throwing out leaves left, right, and centre days later.
Cut back to my nutrient water cuttings. Sure, they had roots within days, but they’re still not doing much in terms of growth.
These hacks are still good to know though. Rooting is something I have no patience for, so knowing I have a couple of tricks that can result in this taking a couple of weeks rather than months makes me more likely to propagate.
I really need to try changing the nutrient water every day. I expect incredible results.
Another interesting experiment was trying to root a cutting with a Pothos in the water. It seemed to work VERY well, and I had roots in days, but as I explained in the article, that cutting had a suuuper long aerial root. That could definitely have had an impact.
All these experiments will be repeated, but only so many props will fit on my coffee at once. I need space for my coffee cup, plus a healthy gap so I don’t accidentally drink prop water (top tip: keep the one with nutrient water furthest away).
In my experience, cuttings that have aerial roots have the potential to root very quickly, but that doesn’t necessarily mean that new growth will sprout equally quickly. In fact, it seems that plants that root fastest take the longest to start to grow.
However, having a few tricks up your sleeve to speed up root growth can mean that you can perform life-saving operations when necessary.
For example, if you’re saving a plant from stem rot, rooting it quickly can be the difference between a healthy cutting and a very expensive rotten stick.