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Ask a Master Gardener: Garden Myths Unveiled

By Alice Marty, Mobile County Master Gardener,

Every hobby has its fair share of myths and legends, and gardening is certainly no exception. From so-called foolproof fire ant remedies to the moss that supposedly destroys trees, the fascinating stories exchanged within gardening communities never fail to captivate.

The following are well known garden myths, accompanied by the kernels of truth that sparked them.

“If it’s published, it must be true.” (FALSE)

Make sure to verify the accuracy of any gardening information you come across in websites, articles, or books.  A reliable method is by confirming the credibility of the source, such as checking if it is from reputable institutions like land grant universities or agriculture extension services.

Grits Control Fire Ants (FALSE)

Unfortunately, the idea that grits can control fire ants is not accurate. Research has shown the theory that fire ants will eat the grits which then will swell in their stomachs until the ant explodes, is false.  Worker ants cannot eat solid food.  The only members of the ant family that can eat solid food are the oldest larvae.  They feed the rest of the colony food in liquid form. 

It's a common misconception that not only grits, but also soap, soda water, diesel, or citrus peels can eliminate fire ant nests. However, these methods are ineffective. Even shoveling ant mounds together to provoke a fire ant civil war may seem dramatic, but it doesn't work either. While some of these treatments might make the ants relocate, they usually won't move very far.

Club soda is another common home remedy for fire ants. As the reasoning goes, the carbon dioxide from the bubbles suffocates the ants in their tunnels. While the logic is appealing, in actual practice this treatment has little to no effect. The origin of this myth is misunderstood advice given by Walter Reeves, a Georgia Extension agent. Reeves was not suggesting that the soda would work, but a couple of misquotes later, he was famous for the club soda cure-all.

Regrettably, there is currently no known method to completely eradicate fire ants from a specific location. To manage fire ants, we suggest utilizing boiling water, safeguarding the native ant species that compete with them, and employing garden-specific baits and contact pesticides only when necessary. For further information, please refer to the UF/IFAS publication titled "Managing Imported Fire Ants in Urban Areas".

Spanish Moss Kills Trees (FALSE)

Gazing up at a majestic oak adorned with abundant Spanish moss draping from its branches, it's important to note that Spanish moss does not harm trees. In fact, this harmless air plant, known as an epiphyte, relies on its host tree solely for support. While it tightly clings to the branches, its roots do not penetrate the bark nor deprive the tree of any essential nutrients. 

Marigolds Deter Nematodes (TRUE, but ...)

Many marigolds produce alpha-terthienyl, a chemical that can reduce plant-parasitic nematodes. However, simply planting marigolds alongside another crop has not been proven effective in reducing nematode populations. To effectively ward off nematodes, marigolds must be planted as a cover crop at least two months before the desired crop.

However, this can be costly, with an estimated seed cost of $20 needed to cover a 10' x 10' vegetable garden bed with marigolds planted 7 inches apart. Additionally, not all marigolds produce enough alpha-terthienyl to control nematodes, and not all nematodes are affected by this chemical. Finding the right marigold for a specific nematode infestation requires research and trials. Lastly, tilling marigold plants or their byproducts into the soil is not an effective control method, as alpha-terthienyl is only produced by living marigold root tissue and becomes inactive when exposed to sunlight. If you're looking to reduce nematode populations, soil solarization using sunlight may be a more effective approach.

Apply turf fertilizer early in the spring to help encourage new growth.  (FALSE)

It's best to steer clear of fertilizing too soon in the growing season as it can lead to excessive leaf growth before the roots have had a chance to establish.  For Bermuda and St. Augustine grasses in our area, the first fertilization can be done in April, but for Centipede, wait until May. Fertilization is crucial for achieving a healthy and high-quality turfgrass stand.  However, over-fertilizing or fertilizing at the wrong time can cause issues like groundwater contamination as the unabsorbed fertilizer washes away.  A successful and eco-friendly fertilization plan considers several factors.

•              Native soil fertility levels (soil test)

•              Amount and source of nutrients in the fertilizer

•              Fertilizer application frequency

•              Fertility requirements of the specific turfgrass species

•              Time of fertilizer application

The moral of the story? If a home remedy sounds too good to be true, call your county Extension office or the Master Gardener Helpline 1-877-252-4769 for home and garden information supported by science.

Fact-Spanish moss does not harm trees. Photo by JudyStout

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