As gardeners, we would all appreciate a quick way to keep our plants happy. Some turn to the contents of their home to try and most of us have aspirin in our home. After all, aspirin helps us; Doesn't aspirin for plants also help your plants?
While much study is still needed to determine whether it is actually viable, early information seems to suggest that this claim has some validity. The question really is, is it the shining solution to so many problems it is believed to be!
It has long been touted by cut flower arrangers that aspirin helps cut flowers last longer. But is that true? Can it actually produce bigger, healthier tomatoes? Does it actually prevent some plant diseases or improve your plants' drought tolerance? These and other claims have been made over time.
So let's dive headfirst into the science behind giving aspirin to your plants and clarify what is known and what is not. We'll find out if this popular medicine cabinet item should find its way onto your gardening supplies shelf!
What is aspirin?
Does aspirin really make sense for plants? Source: Browserd
From its earliest form, what we now call aspirin has been used medicinally in a variety of ways. Its first documented use was in ancient Sumer, noted on clay tablets as a cure for fever. Indigenous peoples in the United States used the bark of willow trees to make a drink that relieved pain; Pasture use for a similar purpose was also common among the Greeks and Chinese. In other parts of the world, various other plants containing a particular natural substance were used for similar purposes. Today this substance is the purely natural predecessor of our modern aspirin.
But what kind of predecessor was that? That would be salicin, which is found in most plants of the Salix species, as well as in plants of the Spiraea species and a few others. The purified form known as salicylic acid was first synthesized in the laboratory and widely used in medicine in the late 1830s by an Italian chemist named Raffaele Piria. Those of us who aren't doctors probably know best about salicylic acid as an over-the-counter drug used to remove warts from the skin, but it has also been used to treat fever or pain.
Aspirin itself first appeared in 1897 when Felix Hoffman, a German chemist at Bayer, first synthesized acetylsalicylic acid. In the beginning, however, it was a touch-and-go; At the same time as the synthesis of aspirin, Bayer had discovered a new potent drug that they wanted to introduce in their cough syrups. We now know that other drugs like heroin are a very addicting and very dangerous drug! As a result, aspirin was suppressed and almost forgotten until another Bayer scientist pushed the development forward.
The main differences between salicin, salicylic acid, and acetylsalicylic acid are very small in terms of chemical differences, but enormous in terms of today's benefits.
Salicin tends to contain a number of other organic compounds and it is not uniform in the organic matter in which it is formed. Some plants contain more salicin than others, so finding the right dosage has been difficult and it may occasionally contain other hazardous substances from the bark from which it was extracted.
Salicylic acid loses all other organic compounds and is a purified form of salicin. This powerful drug is used topically to remove or rub off the surface layers of the skin. It was originally used internally for the same reasons as salicin in willow bark. However, it did cause stomach upset and was known to rub off the lining of the stomach, making it dangerous while still being effective for its intended use.
Acetylsalicylic acid, the active ingredient in aspirin, has a very minor change in its chemical composition. This tiny variation makes it less likely to cause stomach problems in humans and has now led to its widespread medicinal use as a pain reliever and fever reducer. But even that small change made it a viable drug for treating a heart attack that didn't come to light until the 1970s.
The name "Aspirin" is said to be a mixture of three things: "Acetyl" to identify it as a new derivative, "Spiraea" for the meadowsweet-related plant from which salicylic acid was obtained during the original manufacture of the drug, and " in “, a common ending of drug names at the time.
Common claims for aspirin and plants
After crushing aspirin, people dissolve it in water. Source: danielfoster437
In addition to modern medicine, aspirin is said to be effective in a number of gardening applications. But how effective is aspirin in the garden? Let's look at science and see what has been discovered so far.
Aspirin for cut flowers
Let's look at these first. Many gardeners swear by dissolving an aspirin tablet in water and using that in a vase to water their cut flowers. The claim is that the aspirin helps the plants last longer.
But in reality that's not true. Flowers produce calluses, a sticky or rubbery material that seals injuries. Most commercial flower preservatives contain sucrose to feed the flowers, an acidulant to neutralize the cornea so the plants can continue to absorb their nutrients, and some form of antibacterial or antifungal agent to prevent mold or rot.
Aspirin does not prevent callus formation, which means that the flowers will continue to dry out even if they are dipped in a vase of aspirin water. The plant seals its injuries, and no amount of aspirin water can prevent this.
For cut flowers, choose a commercially available preservative for the best longevity. If you can't get your hands on a commercial preservative, many florists recommend adding some 7-Up to the water, as it contains both sucrose and citric acid (the latter will help reduce the chance of mold or mildew building up). but that only works for short periods of time.
If you go a step further, using aspirin for preserving Christmas trees isn't very effective either. Although trees do not produce calluses like most cut flowers, they also need more water and sucrose. Aspirin water offers no real benefit here.
Aspirin against pests and diseases
Many people claim a number of wildly different things for aspirin in the garden. Among these there are claims that aspirin can be used as a pesticide and as a fungicide.
There is some evidence that salicylic acid may play a role in prevention, but not curative, in at least one bacterial disease. In a study, US Department of Agriculture scientists sprayed a selection of tomato seedlings with salicylic acid. After spraying, the plants were exposed to a plant pathogen, specifically the bacteria that cause Potato Purple Top disease. Spraying aspirin early on reduced the spread of bacteria by almost half.
However, this was more preventative than curative. The use of salicylic acid (SA) after a bacterial infection appeared to have little to no major effect on the bacterial disease, probably because the plant was already infected with the disease. It is believed that prior application of the acid triggered preventive systemic resistance in the plant's immune system, which helped defend it against infection. It wasn't a cure for the plant, but an immune system boost.
Later research found that many plants naturally produce SA at the sites of infection for various systemic plant diseases. This does not fight the infection directly, but triggers an immune response from the plant. Plants sprayed with SA develop their own natural response to fighting the pathogen.
A 2019 study found that while SA is effective at triggering the systemic acquired resistance response, it is not without its drawbacks. It has a short lifespan in plants because they synthesize it quickly. In addition, an excess can actually be toxic to the plant.
Remember, all of this is about salicylic acid itself, not aspirin. The active ingredient in aspirin, acetylsalicylic acid, has not been tested or studied in the same way as SA. Therefore, it is uncertain whether the use of aspirin in the garden will have an immune-boosting response like that of salicylic acid, or whether it will have toxicity similar to that of plants when used over-the-counter.
In the case of pests, there is even less research to support this claim. In many cases it is mistakenly believed that once something is believed to prevent disease, it also prevents pests. That doesn't seem to be the case here. There is no evidence that strengthening the plant's immune system in response to salicylic acid application provides natural resistance to pest infestation. While a healthier plant is often less attacked, that doesn't mean using aspirin as a pesticide in the garden would be effective, especially since it's not even an antifungal.
To sum it up, while it is possible to use aspirin tablets dissolved in water to prevent some bacterial plant diseases (although it hasn't been shown to be effective and requires more research), it isn't really a pest repellent.
Aspirin for rooting plants
Aspirin is a common household item. Source: OSU
This idea stems from the earlier forms of salicin, from which salicylic acid and later acetylsalicylic acid were derived. It was believed that cutting up a large amount of willow and soaking it in water would naturally produce a material that could be used to help plants develop roots faster. As a result, willow water became a common additive in gardening.
The problem with this concept is that aspirin is not known as a root hormone. There are only a few naturally occurring root hormones called auxins. Auxins slow down the side bud and encourage root development. Probably the most common one in the average gardener's arsenal is indole-3-butyric acid, as it is by far the most commonly used in powdered root hormones.
Some limited testing has been done to see if SA has an effect on root growth, but it has not been shown to be conclusive.
At least one 2008 study of sunflower seed germination was conducted to see if acetylsalicylic acid (ASA) or SA was effective in promoting larger root growth in the newly germinating seeds. Extremely low levels of SA or ASA resulted in elongation of the early embryonic roots, but the more SA or ASA added, the worse the results became. At higher levels the seeds had great negative effects, and at the highest dose the seeds did not germinate – the addition simply caused them to die. Overall, the use has been refuted in general.
While there is no recent study article that says, "Don't use aspirin as a root hormone," it is clear that it has no real benefits this way. It is better to leave the root system to the plant's own system or perhaps add a little indole-3-butyric acid if you want to offer a real auxin to help. Aspirin is not the best solution here.
Aspirin for plant tolerances
Can you improve the drought tolerance of a particular plant by using aspirin? How about his tolerance to heat or cold?
Some signs suggest that this might actually be true. While salicylic acid is more widely studied for this role, acetylsalicylic acid can also be effective in improving plant tolerances to various problems.
The effectiveness of using aspirin in this way stems from the SAR mentioned earlier: systemic acquired resistance. Just as aspirin triggers the plant's defense systems against bacterial infections, it can stimulate the plant's defense systems to stimulate them to protect themselves from other conditions.
But here's the problem: while results have shown that this actually works, it is not really a substitute for properly caring for your plants. Consistent feeding, watering, and caring for the leaves and stems of your plants will give you a better effect than spraying aspirin water on them.
Using aspirin this way still poses potential risks in the garden. Keep in mind that an aspirin water spray has short-term immune boosting effects and it is simply not a long-term solution. Take care of your plants properly, provide a cold frame frame in cold weather and shade cloth in hot weather, water them regularly and you will have better overall production and know that it is working.
Aspirin for tomatoes
Now we come to the last claim: aspirin for tomato plants. Some claim that you can use aspirin to improve yields, get healthier plants and heartier leaves, and generally improve all elements of this popular plant.
The results on this are a bit mixed up to be honest. A master gardener from the University of Rhode Island ran some tests on her vegetable garden in 2004 using an aspirin spray on cucumber, basil, beans and tomatoes. Her claims about the effects were incredible: she said the plants were much larger, stronger, and had huge fruits. She also claimed that spraying plants with aspirin water cured diseases.
As you can imagine, this got a lot of attention very quickly. In fact, her account of her "discovery" has been published in several newspapers and has been heavily quoted.
The next year, a PhD in Plant Science from the University of Rhode Island worked with the master gardener to run a slightly more scientific test. As a result, they found that Early Girl tomatoes did not experience a reduction in yield when aspirin or SA were used to induce systemically acquired resistance. Unfortunately, the test found that accurate measurements would require more testing in a much deeper way, as the results they got were very different.
It works? Perhaps. We don't know exactly yet; There has been no update on this particular line of the vegetable garden study since 2005. But we do know that the Rhode Island master gardener's first enthusiastic review of aspirin in gardening applications was very anecdotal. Until their experience can be reliably reproduced so that we know how to use it, aspirin spray is unlikely to be of much benefit to your tomatoes or other vegetables.
Final thoughts
Since it's cheap, these tips keep circulating online. Source: and parsecs to take away
Overall, it seems like an aspirin solution spray could have some effects on plants. However, whether this will be beneficial for your plants remains to be seen. It's not a tomato miracle cure, it certainly doesn't help sunflower germination or rooting, and while it can help with systemic reactions, science still hasn't figured out whether this will work in the long run.
To me, this is a sign that there is still a lot of research to be done on the subject before we know if there are any real benefits to gardening.
Science is a slow process and we have a lot to learn. I wouldn't rule out the possibility of interesting information coming to light in the future. I have to advise against using aspirin in everyday gardening for the time being, if only because of the lack of knowledge. That may change in the future, especially with more research on SAR, but leave this home remedy off your gardening for now.
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