Eggs and eggshells can be used for a variety of purposes in the garden. Many gardeners don't realize that they have an excellent resource right under their nose, perhaps being tossed into the garbage every day after breakfast. Maybe you've heard rumors about using eggs and eggshells in the garden, but it sounds a bit complex so you're a little wary of trying it out.
Eggs and eggshells serve many purposes in the garden: they can lower soil pH, add calcium & other nutrients to soil, help aerate soil, be used as biodegradable seed starters, and be used as mulch.
I don't know about you, but as a frugal-type, DIY-type person, the idea of putting everyday kitchen waste to good use in the garden is satisfying. With a bit of research, you quickly discover that using eggs in the garden doesn't have to be complicated. It can be pretty simple, and if it really is effective--why not give it a try?
There a number of reasons why gardeners have long experimented with eggs.
For starters, they're common. They're readily accessible, and most households buy a carton or two every week. While there are ways to use the whole egg, there are many ways for gardeners to use just the eggshells--the part that usually just gets thrown away.
Secondly, eggs are biodegradable. This seems a bit obvious, but I have to mention it as a key benefit to using eggs and eggshells. They're a natural product, environmentally safe, and the earth knows how to break them down. Growing seeds in an eggshell, for example, and then popping the whole thing into the dirt is so convenient and skips the need for any store-bought seedling trays. If you're growing food in your garden, you can have peace of mind knowing that you've added something entirely natural to the soil.
Eggs are also excellent additions to the garden because they are a source of calcium. Calcium can balance out other chemicals in the soil, neutralize acids, and reduces soil salinity (the saltiness of the soil). Adding calcium can also allow soil to absorb more water.
In addition to improving the soil, calcium is a huge plus because every plant needs calcium. More on that later, but the bottom line is that, while they don't need a ton of it, they do need a steady supply of this "secondary nutrient."
Okay, you might be thinking, we get it. Eggs and eggshells are available, often free (or cheap), biodegradable, and a source of calcium--which plants need.
So what's the downside to using eggs in the garden?
For some gardeners, a perceived downside to using eggs in the garden is the risk of salmonella. And, to be fair, salmonella poisoning is no joke. It is a bacterial disease that affects the intestines. Symptoms of salmonella poisoning are diarrhea, vomiting, fever and cramping. Salmonella bacteria can be found in poultry, beef, milk and eggs. Consuming raw egg is one way that the bacteria can pass to human intestines. Handling and using raw eggs and eggshells--especially next to the fresh fruit or vegetables we might be growing--goes against everything we've learned about safe food handling in the kitchen.
Concern over salmonella is a legitimate one, and the question of salmonella risk by using eggs or eggshells in soil is one that has been explored here by Michigan State University. To summarize their conclusions, egg shells added to soil as fertilizer make up such a small percentage of the overall soil that contracting salmonella from them is not considered a risk.
Perhaps you have small children living at your house who seem intent on discovering any risk, however miniscule. As I read through the research about salmonella risk, all I can picture is a cute toddler leaning over my garden bed, stuffing fistfuls of dirt into his mouth when I'm not looking. For whatever reason, if salmonella is a concern for you, you can cook eggshells in advance to dry them and kill any bacteria, or compost them before adding the compost to your garden soil.
Cooking eggs at 175 to 200 degrees, for about 30 minutes, should dry them nicely and prevent any disease.
All right, there's the big picture.
Eggs are beneficial, and any risk they pose is negligible or pretty easy to get around. Now let's take a look at specific ways eggs and eggshells can be added to a garden near you.
Eggs as fertilizer
Eggs are a great fertilizer for a number of reasons.
Reason number one: eggshells are a great source of calcium & help lower soil pH
Betchya didn't know that Iowa is one of the leading egg-producing states. Well, it turns out that Iowa State University tested and confirmed that eggshells can be used to help lower soil pH.
When added to the soil, the calcium in eggs can reduce the soil acidity and help you strike just the right balance for your plants.
On the pH scale, pH levels of 0-6 are acidic, with the lower the number being the more acidic. A pH level of 5 is the level of coffee or beer, for example, while a pH level of 2 would be in the same category as gastric acid. A pH level of 7 is neutral, and as you move up the scale you get more and more alkaline. A pH level of 10 would be the range of hand soap, while bleach would have a pH level of 13.
One way to test your soil is to buy a soil testing kit from a garden centre and follow the instructions.
A simple DIY way to test your soil pH
If you're the DIY type (so many gardeners are, let's be real), a simple test you can do only requires soil, water, baking soda and vinegar.
Collect 1 cup of soil from different areas of the garden. Give it a quick stir. Get two containers and put two spoonfuls of soil in each container.
In one container, add half a cup of vinegar to the soil. If the soil fizzes, the pH level is likely between 7 and 8, and you know you've got alkaline soil.
If nothing happens, set that container aside and turn to the second container of soil. Add enough distilled water to get the soil in the container muddy. Add half a cup of baking soda. If the soil fizzes, you've got acidic soil, likely with a pH level between 5 and 6.
No reaction to either test? You've got neutral soil, sitting around a pH of 7.
Eggshells can add calcium to soil
For most gardens, a pH level of 6.5 is just right--slightly acidic to neutral. Some plants, however, prefer to be on the neutral or even slightly alkaline side. Some vining plants, for example, can thrive on the less acidic side.
As kids, many of us learned that calcium is an important nutrient for people, to grow strong bones and teeth. As mentioned earlier, plants also need calcium. Every plant. While it is considered a secondary nutrient, as plants do not require large amounts of it compared to other nutrients, calcium is still a significant nutrient. Plants use calcium to construct cell walls; once this calcium is used in cell walls, it is "locked in" and no longer accessible to the plant. A plant needs a source of calcium for continued growth. If a plant has enough calcium, it can construct strong cell walls to deter disease, and it will grow strong and healthy rather than "spindly" looking.
All plants need calcium, but some plants are extra keen on calcium. These include: apples, broccoli, brussels sprouts, cabbage, carrots, cauliflower, celery, cherries, citrus, conifers, cotton, curcurbits, melons, grapes, legumes, lettuce, peaches, peanuts, pears, peppers, potatoes, tobacco, and tomatoes.
Egg shells might prevent blossom end rot
If a plant doesn't have enough calcium, one problem that can appear is "blossom end rot." Tomatoes, eggplants and peppers are most vulnerable to this symptom of calcium deficiency. Melons, cucumbers and squash can also be susceptible. Blossom end rot is characterized by a water-soaked, rotten looking spot on the blossom end of a fruit. Not pretty, and certainly not appetizing.
Blossom end rot is a sign that your plant is hungry for calcium. That said, the issue--at least for some soils--is that blossom end rot isn't caused by calcium deficiency per se, but water transport in the roots.
One way to combat blossom end rot is to add crushed eggshells to the bottom of planting holes. This way, the plants will have a continual source of calcium as they grow, and the physical structure & pieces of eggshell can help aerate the soil.
As a side note, blossom end rot can also be caused by improper watering, especially of container plants. Ensure that you water your plants consistently; if the soil becomes completely dried out, the roots are damaged and can no longer access the calcium that already exists in the soil.
Egg shells help aerate soil
Another thing eggshells as fertilizer do is to aerate the soil. It's been explained in depth in other posts, but it is very important to have lots of nutrient-rich organic matter in soil, for a lot of reasons (aerating the soil being one of them). Organic matter is anything that comes from nature--animal or plant based. Soil that is high in organic matter is rich in nutrients, dark, textured, and can hold a lot of moisture. As organic matter, crushed eggshells that have been worked into the garden help create space in soil, space for air, for growing roots, and for water.
How to use egg shells as fertilizer
If you're keen to use eggs or eggshells as fertilizer in your garden (as you should be after reading this information!), there are a few ways to do that.
Whole eggs as fertilizer
One way is to actually put a whole egg into the soil. This is just as simple as it sounds--put a whole, uncracked raw egg into a planting hole for tomatoes.
If you choose to go this route, you may feel a twinge of camaraderie with generations of gardeners before you as you put that egg in the ground. It has been an old "secret" and tradition for many tomato growers.
A few caveats, though: make sure you dig the hole deep enough, to avoid tempting various animals to dig up the eggs. You have basically put a tasty meal right in the ground, but you want that meal to go to your little tomatoes, not to an opportunist rodent. Also, nobody wants that smell.
If you're nervous about pests in your garden, then add your eggs and eggshells to your compost and get it into the soil that way.
Crushed eggshells as fertilizer
Alternatively, simply crush up eggshells (cooked beforehand, if you're worried about salmonella), and work them into the soil. Many gardeners claim that this is more effective, anyway, as the plants can access the nutrients more readily than they could from a whole egg.
Eggshell vinegar solution as fertilizer
Another way to add eggshells to your garden is to make an eggshell vinegar solution to use as fertilizer.
First, dry your eggshells by putting them in the oven at 200 degrees for half an hour. Next, roughly break them up with your hands. Grind up the dried eggshells (in a coffee grinder, for example) and add to equal parts white vinegar. The calcium in the eggshells will react with the acidity of the vinegar, releasing calcium to be water-soluble and readily accessible for plants. The mixture will foam, and you should let it sit for 30 minutes. When it stops bubbling, you can add about half a cup of the mixture to a gallon of water. Add it to your plants, such as tomatoes, in small amounts before they start to flower.
Whatever method you choose--eggs in compost, whole eggs plopped into the ground, broken eggshells scattered in soil, or ground up eggshells mixed with vinegar--eggs are an excellent, all-natural fertilizer.
How to use eggs as seed starters
Eggshells can also make very handy (and free!) seed starters.
To do this, save some intact, deeper shell halves. Sterilize them by boiling them, or by baking them in a 175-200 degree oven for about 30 minutes. If you want to really have "no waste" seed starters, then you could pop them in a cooling oven to save energy.
Next, make a small hole in the bottom of each shell half with a nail or awl. This is for drainage.
Put the shell halves back in the egg carton, and fill them with some soil. You now have what looks like the beginnings of some kind of cute, Easter-inspired craft. Plant your seeds as you normally would, and when you're ready to transfer to your garden, you can bury the eggshell with it. Voila! Biodegradable, free, and nutrient rich seed starters.
You will have the added bonus of visitors to your home admiring your creativity and resourcefulness, so be sure to put the seedling tray in a prominent spot.
Eggs as pest control: fact or myth?
Although lots of gardeners use eggs & eggshells as a natural pest deterrent, there's little science-based evidence to back up the claims. That said, there are a few ways that folks purport to use eggs for pest control in the garden.
Crushed-up eggshells mixed into the soil, or surrounding a plant, can (theoretically) be used to deter slugs and snails. The logic is that the eggshell shards are sharp, so soft-bellied pests will avoid sliding across them.
While many gardeners claim eggshells as effective slug and snail deterrents, some tests like this one claim that this is an easy-to-bust garden myth. In this test, slugs seemed to be completely undeterred by the eggshells surrounding a leafy green; in fact, they seemed attracted to it, likely because of egg residue in the eggshells.
I haven't personally tried this out, but I have to say that the photos of slugs sliding all over the eggshells are quite convincing. They seem quite immune to any intended discomfort.
Another way that gardeners use eggs as a pest deterrent is to formulate deer sprays using egg. Apparently, deer hate the smell of eggs.
However--and, if you're like me, this is a deal-breaker--other pests love the smell of egg! By deterring deer, you might just be attracting rodents and raccoons. Our neighborhood is full of black bears, so there's no way I'm going to risk luring them into my yard. But, if the problem in your area is deer, this may be worth looking into.
Eggshells as mulch
Perhaps you went a little overboard in collecting eggshells all winter long, and now have a pile of them dried out, ground up and ready for use in the garden.
They can be put to use! All of them!
If you have enough eggshells, you can spread them in a layer on top of your soil to act as mulch. They will help the soil retain moisture and discourage weeds, in addition to adding nutrients to the garden.
On an aesthetic level, a thick enough layer of eggshells can accent dark soil and green plants quite nicely.
Eggshells as bird food
Perhaps, for you, your garden is more than just a place to grow things. It's also a place to interact with surrounding nature, especially birds.
This is definitely true for my family, and for many other gardeners. The joy of watching our plants grow in the summer is balanced with the delight of watching our daily visitors fly through in the winter. (Remember those pesky black bears in my area? No bird feeders allowed in the summer months! We can only put them out when the bears are safely hibernating.) Our family takes great care to maintain several bird feeders, tailoring the menu to attract specific types of birds.
Turns out, pretty much everything needs calcium. Birds can benefit from the calcium in eggshells, especially females in spring. If you want to help supplement the diet of your feathered friends, be sure to sterilize the eggshells by boiling or baking, as mentioned earlier, and then finely crushing them and mixing them into birdseed.
What kind of plants are eggshells good for?
Most houseplants and garden plants benefit from eggshells in their soil, since eggshells are a source of calcium. And calcium is used by plants to provide firmness & solidity to their stems.
In addition, calcium from eggshells can help raise the pH of overly acidic soil, making nutrients more available to plants that otherwise don't grow well in acidic soil.
Can you put raw eggshells in the garden?
Eggshells can be added raw to soil in your garden, and provide additional calcium for plants as well as raising the pH for overly acidic soil. However, keep in mind that eggs and eggshells might attract critters--especially animals with a keen sense of smell.
Are eggshells good for compost?
Eggshells are great for compost for the following reasons: eggshells add calcium to soil, the calcium in eggshells raises the pH of acidic soil, and eggshells help aerate soil. When adding eggshells to compost, you don't need to crush or mash the eggshells, but if you do, the crushed eggshells will decompose a bit quicker, since they'll be in smaller pieces. In addition, if you're properly composting eggshells--like in a hot compost pile that reaches 140-160 degrees Fahrenheit--the composting heat will kill any salmonella bacteria.
Now get crackin'!
Hopefully by now you have realized that eggs are an egg-cellent addition to your garden, in many ways. (Okay, I'll stop with the puns there.) Eggs are a natural way to boost calcium in the soil, add mulch, give a treat to the birds, start your seeds, and (in some cases) deter pests.
Eggs and gardening. No longer separate in your mind, but forever scrambled together.
(Sorry, I couldn't resist.)