Garden Myth: Aspirin as Rooting Hormone

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Photo: consommerdurable.com & pngtree.com

Question: Can you use aspirin as a rooting hormone?

Zofia Walnik

Answer: No, or at least, you could, but it won’t likely be of any help.

Of course, information to the contrary abounds on social media. Usually one of two methods is recommended:

1. Adding a regular strength aspirin tablet to a glass of water and rooting the cutting in the resulting solution.

2. Adding a regular strength aspirin tablet to a glass of water and soaking the cutting for 1 hour before inserting it into potting soil.

Neither of the two methods will get any notable boost from the aspirin. The second method will be more successful than the first, though, because cuttings rooted in potting soil grow much more vigorously than those started in water. (Read Starting Cuttings in Water: Not Such a Good Idea to better understand why.) But that has nothing to do with the aspirin treatment.

Two brands of aspirin, one labelled ASA.
Aspirin may also be labelled ASA. Photo: Daniel Case, Wikimedia Commons

Aspirin is acetylsalicylic acid (ASA), very similar to the salicylic acid that plants themselves produce when they are stressed. Used at very low doses (it’s toxic at high doses), ASA has all kinds of beneficial effects on humans, but very little on plants.

In different studies, ASA was generally found to have no effect on rooting. In the few cases when it did, it tended be more likely to inhibit rooting than to stimulate it, although in some cases there was a very slight beneficial effect. However, either way, the effect, positive or negative, was so slight that “the results were not scientifically valid.” In other words, the effect of aspirin on cuttings is not worthy of mention. So, essentially, you simply waste an aspirin tablet when you apply one to a plant cutting.

But precisely, since aspirin has essentially no effect, people who use it cry victory when their cuttings take root and then spread the good news on Facebook, Twitter, etc., without thinking that if they had not used aspirin, the result would likely have been just as good, even slightly better in some cases. 

Most soft stem cuttings produce their own rooting hormones and don’t need outside help. That’s why rooting cuttings is so easy!

Cutting with rooting hormone applied.
For plants that are difficult to root, applying rooting hormone gives the best results. Photo: hgic.clemson.edu

For cuttings with semi-woody and woody stems, which are more reluctant to root, there are commercial rooting hormones that help a lot. But aspirin? It’s just a waste of time!

To learn more about the art of taking cuttings, read Rooting Cuttings Step by Step.