Brooklyn Orchids

What Are Aerial Roots and What Should I Do with Them?

Phals with aerial roots
Phals with aerial roots

If you’ve asked the question above, you are not alone! Let’s first geek out a little about words and define “aerial roots.” The prefix “aer-” is derived from the Latin word aer, which means air. So the word aerial itself is the key to unlocking the meaning. In orchids (as well as many other plants), aerial roots are roots that grow from the base of the plant upward, or out into the air, rather than down into the soil or inside the pot.

What is the purpose of aerial roots? Well, a great many types of orchids, including the most popular household orchids—Phalaenopsis—are epiphytes, as are Dendrobium, Oncidium, Vanda, Cattleya, and many many more. This term is used to describe plants that grow attached to other plants, trees, branches, stumps; in other words, epiphytes do not grow in soil. Rather, an epiphyte’s roots are exposed to the air (hence the term “aerial roots”) and cling to the surface of tree trunks and other organic matter while soaking up water and nutrients from the plant’s environment. These roots form the building blocks of the orchid and are absolutely vital to its ability to thrive.

So when you find roots jutting up out from your orchid’s pot at home, don’t panic—this is 100% natural. It’s how epiphytic orchids would grow in the wild, like so:

Dendrobium attached to a tree in San Juan, Puerto Rico
Dendrobium attached to a tree in San Juan, Puerto Rico

Here I am checking out Broughtonia sanguinea orchids attached to a tree in Ocho Rios, Jamaica:

Broughtonia sanguinea in its native habitat
Broughtonia sanguinea in its native habitat

Because of their epiphytic nature, many orchids can be mounted on bark, tree fern, or other organic materials for a unique display, like this beautiful specimen I saw at the Brooklyn Botanic Garden last year:

Mounted orchid @ BBG
Mounted orchid @ BBG

Those of us who like our plants to look tidy may be horrified by the often haphazard nature of aerial roots, but it’s honestly best to leave them as is. Trimming aerial roots off an orchid deprives the plant of its foundation and its ability to absorb water and fertilizer, so I definitely don’t recommend doing that unless the roots are truly unhealthy and rotting (see my post on how to identify healthy vs. unhealthy roots)! You can try soaking the aerial roots in water for a bit to make them more pliable and then attempt to tuck them down inside the pot, but even when moist the roots are still quite fragile and prone to breaking, to the detriment of your orchid.

Instead of trimming or tucking, why not just allow the aerial roots to grow as they like? The one down side to letting this natural process take place is that aerial roots will dry out more quickly than the ones down inside the pot. There’s an easy solution here: simply mist the aerial roots with tap water at least once a day. Misting will help keep those roots happy until your next watering session. Personally, I’ve made a habit of misting my orchids’ aerial roots in the morning when I get up.

You may be wondering “Do I need to repot my orchid because of its aerial roots?” Aerial roots in and of themselves don’t mean that your orchid needs to be repotted. Many types of orchids actual prefer to be somewhat pot-bound, meaning that they like a fairly tight fit inside the pot. Repotting may not “take care of” aerial roots—especially if you end up breaking them off while trying to stuff them down into the potting medium.

One more thing to note: if you find roots and new leaves growing along your orchid’s flower spike, you may actually have a keiki (plantlet) developing. It could look something like this:

Phal with keiki growing off end of flower spike
Phal with keiki growing off the end of flower spike

Those roots are aerial by definition, but when they appear along a flower spike rather than at the base of the plant, they are an indication of a whole new plant growing off of the original! You can read more about keikis and what to do with them here.

Let those aerial roots grow free and see where they take your orchid. As long as you keep them misted, they should remain happy and contribute to the orchid’s overall health!

 

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