I love eggs. I eat them often for breakfast and always have a carton of fresh farm eggs on hand. One day, I hope to have a few chickens and collect fresh eggs each morning, but until then, I’ll settle with my CSA eggs. Once I have my own supply, I’ve considered how I can go about using eggshells in the garden.
I could do without the flip-flopping claims the healthiness of eggs. Honestly, I believe that no food is bad and that demonizing food products is the fastest way to disordered and restrictive eating. I don’t evaluate foodstuffs as either bad or good. Everything is neutral, and I approach everything in moderation.
In the garden, though, moderation is thrown out the window. When people make claims, it’s often “go big or go home.” Tricks are peddled as miracle hacks, and it’s tough to distinguish truth from myth.
Below, I’ll go through the various claims about eggshells in the garden and attempt to dissect each one. Whatever you take from this article, I hope that you finish with confidence to determine fact from fiction and a healthy skepticism that will help you when you’re offered up advice that over-promises and may sadly end up under-delivering.
A Closer Look at Eggshells
The deceptively tough eggshell keeps baby chicks safe and sound until they’re ready to hatch. It also keeps your breakfast preserved until you’re hungry enough to start scrambling. Eggshells are primarily made up of calcium carbonate and may also contain traces of magnesium.
Claims About Eggshells in the Garden
A quick Google search will reveal hundreds of articles about the wonders of eggshells in the garden. Use them for everything from pest control to fertilizer. But do the claims hold water? Let’s take a look at the apparent benefits to using eggshells in the garden and find out which have some merit and which you can ignore.
Egg Shells for Pest Control
Claim #1: Eggshells are the ideal organic pest control solution for soft-bodied insects like slugs and snails. The sharp edges of shell slice through insect bodies and keep them from feasting on your plants.
The reality: Simply put, this doesn’t work. I say that from experience because I tried it as a young gardener and still had slugs eating my lettuce. It’s a myth. Slugs will easily find a way around or climb over the shards unscathed. I’ve watched slugs slide over eggshells without a care in the world. The shells aren’t sharp enough to pierce their little bodies. You’ll have better luck with diatomaceous earth.
Claim #2: Eggshells repel deer since the smell repulses them. Spreading eggshells in and around the garden will keep deer from munching on your plants.
The reality: I’ve seen this claim in more than a dozen places online, and while I can’t find any scientific study to refute this claim, I highly doubt it’s something that will make a marked difference, especially if you have a severe deer problem. Plus, leaving whole eggshells in your garden may attract small mammal pests to your garden. That said, some people swear by it, so give it a go if you’re looking for a natural deer repellent.
Claim #3: Eggshells can be used in place of diatomaceous earth.
The reality: Nope. They’re not the same. Eggshells don’t repel pests. They don’t have the same properties as diatomaceous earth. Even though they look similar, they don’t work the same way.
Egg Shells as Fertilizer
Claim #1: Placing crushed eggshells around your plants is an easy way to provide organic nutrients.
The reality: Over time, eggshells will eventually break down but it takes a while, and if you have an immediate calcium deficiency, placing crushed eggshells around the base of your plants won’t do much. Also, eggshells don’t contain significant amounts of any essential garden macronutrients, so they should not replace your regular fertilizing routine. They’re a good option if you are looking for a long-term, slow method of adding nutrients to your earth.
Claim #2: Handle a calcium deficiency and issues like blossom end rot by adding crushed eggshells to your garden.
The reality: Always test your soil before assuming the problem is a nutrient deficiency. Incorrect pH or other issues (like over or under watering) can contribute to deficiencies. If your plants aren’t able to absorb nutrients in the soil, they’ll develop problems, even if they have access to all the nutrients they need in the soil. Direct application of any type of fertilizer won’t necessarily resolve the issue if your plants aren’t able to access nutrients.
Claim #3: You can soak eggshells and make a calcium-rich tea to use in the garden.
The reality: Eggshells soaked in water actually don’t release much calcium at all. In fact, the amount is extremely minuscule. Any benefit you notice from doing so is probably a result of watering.
Egg Shells in the Compost Bin
Claim #1: Eggshells are perfect additions for your home compost bin or for your city’s brown bin.
The reality: Adding eggshells to your compost is perfectly fine. Just be aware that they break down slowly (slow enough that they’ve actually been found in archeological digs!). Crush or crumble shells to speed up decomposition.
Claim #2: They make an excellent addition to vermicompost.
The reality: Yes! This one is true. Red wigglers love crushed eggshells. The gritty shells allow the worms to grind up other food bits they’ve consumed. Like birds, worms have what’s called a crop and don’t digest food the same way humans and mammals do, so eggshells help with digestion.
Egg Shells as a No-Cost Seed Starting Vessel
The claim: Use spent eggshells to start seedlings without spending a dime. Some people recommend using half of a cracked eggshell filled with seed starting mix to plant seeds in.
The reality: As a last-ditch option, egg shells will work to start seeds, but they won’t be suitable for long. A half a shell doesn’t offer much space for a seedling. Whoever tells you that starting in an eggshell provides added nutrients to your baby plants is misinformed, as well. Your plants can’t suck the calcium right out of the shell, in order to provide nutrients the shell must decompose to release calcium and other trace elements.
My suggestion? If you’re short on money, head to the dollar store to find cheap seed starting tools in the springtime. I’m a big fan of using solo cups. If you have a bit of extra cash, invest in heavy-duty trays that can be reused year after year and you won’t have to waste time cracking and filling tiny eggshells with soil.
Egg Shells as Mulch
The claim: Crushed egg shells are an excellent mulch alternative and help conserve moisture and deter weeds.
The reality: There are plenty of superior mulch options. To be effective, you’d need a whole lot of spent egg shells. Don’t waste your time on this. Use compost, leaf mold, straw, or wood chips for mulch instead.
How to Use Eggshells in the Garden
So is there any reason to use eggshells in the garden if so many of the myths surrounding their use aren’t true? Using eggshells in the garden might not have any positive effect in most cases, but unlike coffee grounds, there’s little harm to tossing them into your potted plants or garden beds.
If you’re still not convinced go right ahead and keep doing what you’re doing with eggshells in the garden. No harm, no foul.
Why Do These Myths Continue to Circulate?
The garden community is rife with information about hacks that will make your life easier. Whether it’s about pest control, fertilizing, or simply growing the biggest most beautiful plants, you can be sure there’s someone somewhere who claims to have the answer to your problem. In my experience, rarely do those miracle suggestions work.
Why do they persist? We want to believe these old wive’s tales and myths because they’re not only an easy way out, they appeal to our nostalgic senses. Are you truly willing to accept that your grandmother is a spinner of yarns?
The reality is that there’s little scientific study being done on these things. Most of the tips and tricks offered up aren’t usable on a larger scale, so they have little impact or importance to the agricultural industry. So no one bothers to verify or check on these claims.
The evidence comes via word of mouth. And the truth is that sometimes these things work. Not because they’re inherently useful, but because other circumstances lead to success.
If you sprinkle eggshells in your garden and find that the slugs have been defeated, that’s not necessarily a sign that the eggshells worked. A number of factors could have contributed to the disappearance of the annoying garden pests; weather, predators, or time of year.
Next time you’re sure that something you’ve done has had a direct impact on your garden, step back and think for a moment. Assuming that there’s causation is bad science, and it’s a terrible way to interpret what’s going on in your garden.
Have you ever used eggshells in the garden? Think back to a moment when you sprinkled them around your plants. Did you have success? Could the success be attributed to anything else you changed in your routine? Let us know in the comments section! We also want to know about other miracle garden claims you’ve encountered. What’s been the wildest piece of advice you’ve come across?