by Barbara Brown
Gardening Grandma says… “Putting eggshells in your vegetable garden adds calcium, an essential nutrient, to your garden soil. Eggshells placed around tomato plants eliminate blossom end rot. Eggshells deter snails, cats, deer and repel slugs and cutworms.” Let’s check it out.
First, do eggshells add valuable nutrients? Yes, according to the University of Illinois Extension, but “The trick is to grind up the eggshells. The smaller the particle size, the better to increase soil calcium levels. A study from Alabama Cooperative Extension compared coarsely ground eggshells (crushed by hand) to finely ground eggshells (resembling a fine powder), along with a comparison to pure calcium Ca(OH)2 and agriculture lime. The Alabama study revealed the coarsely ground eggshells "were not much better than nothing at all." However, finely ground eggshells performed just as well as pure calcium when integrated as a soil amendment.
Does the calcium in eggshells prevent blossom end rot? No. Mississippi State Extension reports that although “Blossom end rot is a calcium deficiency, that deficiency is normally caused by uneven water availability to the plant.” In other words, even if your soil has plenty of calcium, the plant can’t use it without appropriate soil moisture. Therefore, it is recommended that a gardener keep soils evenly moist during the growing season and especially when plants are in bloom. If your plants wilt because of inadequate moisture, the fruit is more likely to develop blossom end rot. https://extension.msstate.edu/blog/can-eggshells-prevent-blossom-end-rot
How to get your soil tested
Texas A&M AgriLife Extension Service Soil, Water and Forage Testing Laboratory offers a soil testing service for a nominal fee. The soil test results are mailed or emailed to you with recommendations for which nutrients are needed and how much of each should be applied.
It takes 2 - 3 weeks to get results so having your soil tested in late winter or early spring will give you time to make necessary soil adjustments before the growing season begins. Use the link below for your Urban and Homeowner soil test submission. The site provides instructions for collecting samples, making payments, and the mailing address for your sample: http://soiltesting.tamu.edu/files/urbansoil.pdf.
Next, what about eggshells deterring pests?
As much as people love the flavor of home-grown tomatoes so do squirrels, birds, and other varmints. The moist, nutrient-rich soil in your vegetable garden may also attract slugs and snails.
• University of Florida comment: “Set up diatomaceous earth or eggshell chips around plants as barriers against snails” https://edis.ifas.ufl.edu/publication/EP629
• Many non-research-based websites supported the belief that egg shells deter cats from your garden. However, State Extension Service sites recommend physical barriers to keep cats out, not eggshells.
• What about deer? Although spoiled (smelly) eggs are often an ingredient in commercial deer repellent, there is no evidence that eggshells placed in a vegetable garden will keep deer from enjoying your growing plants.
• If you do not have too many tomatoes and want to protect those you have, you can wrap each tomato in a mesh sack with a drawstring to tighten around the fruit. These mesh sacks may be found at a craft store or online.
To prepare garden-ready eggshells allow the saved shells to dry thoroughly. To make chips, use a mallet or small hammer to break shells into small pieces. To create a powder, run the chips through a food processor or coffee grinder until the desired consistency is reached. Enjoying your homegrown tomatoes is worth the extra effort to protect your crop!
Happy Gardening!
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