By Rob Hausmann

Technically speaking, a node is the part of a plant stem from which one or more leaves emerge, often forming a bulbous swelling or knob. Nodes are noteworthy to planty people because many things are occurring at this point of junction. Internodal aka between the nodes, sections offer simple ways of plant propagation and other culture practices to control growth and shape so let’s do a deep dive on them!

Obviously this is where a new stem or leaf is going to emerge, but the space between the node and the next node is also very important. The internode, if you will, on the plant stem is the perfect place to propagate a plant. If a cut is made in the midpoint of the internode the plant should be able to trigger itself to release a new growth shoot (axillary bud). Depending on the species these can be rooted in moist soil or water. I always use Superthrive to speed up the process and relive shock from being cut. Usually in one to two months, longer for some plants (Zz) or faster for others (begonia) roots will have formed and it’s ready for its own pot! Protip - Never put wax over the ends of the nodes-this creates an anaerobic environment which will encourage rot and disease. As long as the stem dries a bit and calluses over, it should not rot. If rot occurs and it’s caught quickly enough, it can be removed (I usually go back 2-5cm) with sterilized pruners or a scalpel.

Additionally, one can notch the stem (about ⅓ of the overall thickness) to trigger the plant to push out growth at the nodes. This is most commonly done in the aorid realm however it can work for many other taxa as well, including cacti/succulents, caudex plants, and cane or rhizomatous begonias. I must mention that in all cases I’ve encountered minus cacti/succulents, this is most successful in a high humidity environment (above 70%). Note, the notch should be angled downward so as to not become a water collecting pocket on the stem, which would lead to rot. Notching tricks the plant into thinking it’s been injured and could potentially detach from the main plant. The notch causes the plant to want to send out new roots in the case that it would be detached and fall on the ground. This is a more surefire method for propagating via nodes given they will have a head start on roots!

Another topic worth mentioning in the node realm are ‘spent nodes’. These are cuttings that have already pushed their axillary (forms at the top) buds and then had them removed or they died back. So it basically turns into a ‘zombie’ stem with no cells that can initiate growth because it already activated them and they were removed, thus we get the term “spent”.

The poster child houseplant for this scenario is the Hoya kerrii, folks can get the single leaf cuttings to root but they don’t have enough of the plant contained (axillary bud) so it just becomes a zombie leaf, not likely to grow into the true vine it’s always wanted to be. I have a specimen like this in my greenhouse that has been one single leaf and nothing more since purchased in 2019. It’s cool tho, it’s still alive and it’s a neat single heart shaped leaf.

Second place, and probably the most problematic offender, would be the Monstera borsigiana albo that is commonly sold at the cheapest rate as a cuttings. House plant enthusiasts or collectors want to grow these plants up into the beautiful vines they can become so having a zombie that won’t grow is not ideal. Unknowing (or naughty) growers can sell these rooted zombie nodes that have no capability to grow but look great to the common person because they can appear well rooted and healthy.

Lastly, the growth that is happening in a node is controlled by plant hormones, Mini Dive:

The growth from a node can be triggered by plant hormones Auxin and Cytokinin. Auxin is responsible for the new growth if it’s in equal levels with cytokinin. If there is more auxin (from tip of the shoot) than cytokinin the plant will develop roots. If there is a higher concentration of cytokinin, then the plant will form shoots. Since auxin comes from the top of the plant and only travels downward, this can lead cuttings to begin to root more quickly that come from the base of the plant. Cytokinins are made in the root tips and travel throughout the plant passively. This is why there can be more in a node and it will still root, even though the cells to be activated for the shoot are not present resulting in a spent node!

Rob Hausmann

I’m Rob Hausmann, an ever practicing horticulturist in Denver, Colorado. I enjoy all aspects of plants, from crop production to landscaping to house plants to rare tropicals and cacti. I have my Masters of Science in Horticulture from Colorado State University and currently work remotely as an international wholesale plant broker. I have had many other roles in public and private horticulture including commercial and residential landscaping design/maintenance/install, managing a hop yard, running a CSA, production horticulturist, greenhouse management, and Zoo Horticulturist.

Hopefully one nodes more about nodes, propagation dos and don’ts, and what to be aware of! #sendnodes #gotnodes #whatdoyounode

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