Gardening like a variety of other topics is susceptible to myths. Myths may have a kernel of truth to them which appears to add validity to their claims, but this validity is short lived under the microscope of scientific investigation. This is one thing I particularly like about the Tulsa Master Gardeners, information we share and use to answer your questions is research-based, university-sourced information. If we tell you something, you can rest assured there is science to back it up and I am good with that. This research-based approach can come with a negative consequence now and then when we unfortunately shine a less-than-positive light on someone’s yearly garden rituals. Oftentimes, the response to our advice is that we don’t know what we’re talking about. Believe it or not, we try very hard to keep our “we don’t know what we are talking about” advice to a minimum. 

One distinction we humans need to keep in mind when evaluating information on gardening (or any topic for that matter) is to understand the difference between causation and correlation. 

When teaching gardening classes I use the following illustration. I wear a Medical ID necklace. I tell the class instead, that it is a necklace I wear to protect me against elephant attack. It must be working because I have never been attacked by elephants. This is correlation, not causation.  

My wearing the necklace to protect myself from elephants and the lack of elephant attack is correlated, but the wearing of the necklace does nothing to protect me from elephant attack. If it did, that would be causation. Since it doesn’t, there is no causation, only correlation. Many a garden myth or life myths in general are rooted in correlation stories, but in reality, they are not measurable or verifiable causal elements. Here’s a couple of real-world garden myths.

 - Ants are beneficial and required for beautiful blooms on peonies.

As most people who have peonies in their gardens know, as the buds on their peonies begins to develop, these buds can become home for a sometimes unnerving quantity of ants. At some point a myth surfaced saying that we need ants to help the peonies bloom.  

The reality is that peony buds have something called extrafloral nectaries on the leaf-like structures that surround the flower before it opens. These nectaries excrete nectar prior to the flower blooming. This external nectar source attracts ants. When an ant locates nectar on a peony, it emits an odor or pheromone trail on the way back to the nest. There, the other ants are alerted, and they then follow the trail back to the peony to feed on some delicious nectar. 

Secondarily it is believed that the presence of ants helps to deter other perhaps less beneficial visitors such as thrips which might be true. But that is where the relationship between ants and peonies ends; the ants are not necessary for peonies to bloom. Casual observers might conclude that since the buds had ants and the buds bloomed, then the peony must need the ants to bloom successfully. But this is incorrect. This is an example of correlation rather than causation. Blooming peonies and ants are correlated, but the ants are not causal in bringing about blooms on the peony. 

- Epsom Salts

The use of Epsom Salts in the garden is another topic dripping with anecdotal correlation without much causal evidence. I’m already bracing for the emails I will get for attempting to discredit this practice, but here’s the deal.  

Epsom salts is made of magnesium sulfate which is one of the secondary nutrients that can be found in healthy soil. Epson salts can be used to boost magnesium levels in soil if you do in fact have a magnesium deficiency in your soil. But bear in mind, magnesium deficiencies in home gardens are not very common and typically only occur in soil that has been intensively farmed for a period of time. It can also occur in soil that has received excessive rainfall or irrigation due to the leaching out of nutrients.  

Here are some myths associated with the use of Epsom salts in your garden. 

Myth 1) Epsom salts help seeds germinate.

    Seeds have all the nutrients they need to germinate and will do so in a damp paper towel. 

Myth 2) When planting tomatoes, put a scoop of Epsom salts in the hole before planting the tomato to prevent blossom end rot. 

Blossom end rot is caused by a calcium deficiency. Adding magnesium in the form of Epsom salts doesn’t help prevent a calcium deficiency but in fact can contribute to a calcium deficiency because magnesium and calcium compete for uptake into the plant thereby contributing to blossom end rot. 

Myth 3) Spraying Epsom salts on tomato plants will encourage a bigger harvest.

This is only true if your soil has a magnesium deficiency. 

Myth 4) Epsom salts are highly soluble so you can’t overuse it. 

Epson salts are indeed highly soluble. However, excess soluble nutrients tend to become pollutants as they are washed out of your soil and into places they aren’t wanted. 

I am guessing that all these Epsom salt garden myths began through a correlative rather than causative event. In each to these myths, it’s logical to assume someone added Epsom salts for some reason (likely read this on the internet somewhere), and that year they had a good crop. Now, they do the same thing every year thinking the myth was the reason. But this myth resulted from correlation rather than causation.

The only way to know you have a magnesium deficiency is to have your soil tested by the OSU Extension office (4115 E. 15^th Street). Be sure to tell them that you also want secondary nutrients tested to find out your magnesium levels. But without yellowing leaves or stunted growth in your plants, you likely have sufficient magnesium in your soil. 

 Correlation is also why many of us wear our lucky team clothes on game day, but we all know we must do that for our team to win…but that’s a different story.   See you in the garden!

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org