Eggshells Are'nt Just For The Compost Heap!

Yummy, nothing will
go to waste!

It's no secret that I come from a family that enjoys eggs.  Breakfast or dinner, you make them and I'm there!  Sometimes I wonder if my "love affair" of them is from the flavor of the eggs themselves or the fact that the shells are so useful in the garden.

For many years, they were a mainstay simply for deterring slugs and snails around the lettuce and spinach plants.  Nevertheless, as we grow and learn, they are now a favorite "go to item" for a wealth of other uses as well.

Let's start with some basics.  Calcium is one of the top secondary nutrients that plants need in order to develop strong cellular structures. When plants are deficient, it can show up as anything from blossom end rot on fruiting plants to tip-burn on the lettuces and brassica's.  Some plants can even develop twisted leaves while others will remain stunted as the plants fail to thrive.  Disease pathogens and insects are also much more likely to attack vegetable plants with weakened cell systems according to several extension services.  Simply put, all plants need calcium to remain healthy and some like tomatoes need a little more than others do.  Eggshells are just one of the resources readily available to get plants a nutrient they need in order for them to do well.

Finely crushed eggshells!

It's quite easy to throw eggshells in the compost heap and let the calcium they release nourish the pile as they break down over time. However, if you're anything like me and want a little instant gratification in the garden, at little to no cost, there are many other ways to utilize them.  These are some of my favorites outside of using them in the compost pile:

1. 1. Calcium and Magnesium Fertilizer/Tea - Tomatoes, peppers, eggplants, and such (the nightshades) all thrive with fertilizers rich in calcium and magnesium.  For an organic boost, boil enough water to fill a 1-gallon jug, add 2 tablespoons of crushed eggshells and 1 teaspoon of Epsom salts.  Let the mixture steep a couple days and strain the eggshells back out. This makes a wonderful foliar feeding early in the morning when the plants stomata (pores) are open.  It is also great as a soil drench, any time of day, which doesn't require you to strain the shells.  If you have hard-boiled some eggs, save the water. Mix 1 cup left over egg water to one gallon hot water (no need to boil) and add the Epsom salts. Shake well and this will be ready to use as soon as the salts dissolve and the mixture cools.
2. Seedlings - Most often, I tend to utilize the compost and worm teas for seedlings with my eggshell bits placed in the pots.  However, the recipe above works very well for supplemental feeding at 1/4 strength.  Some gardeners will actually start their seedlings in used eggshells for the calcium boost.  I have never found this method to be of much use.  For me, it seems as if the containers are too fragile and the plants will readily outgrow their environment.  Instead, whenever potting up, I usually just throw a teaspoonful of shells in the container with a little worm castings and pinch of Epsom salts for good measure. 
3. Planting Hole - One of the best ways to supplement your soil with calcium and trace minerals is to place a handful of eggshells in the planting hole.  Mix these in with other amendments such as compost, worm castings, etc. for a steady supply of food to get plants off to a great start.  While calcium is considered as a secondary nutrient, it does go a long way with the nightshades to keep them healthy during periods of plant stress.  
4. Soil Amendment - If you save your eggshells year round or have a source for supply, they make a wonderful soil amendment.  Because of their high surface area to volume ratio, they decompose rapidly in the soil offering calcium and trace minerals within a very short period.  The smaller you crush the shells before using, the more rapidly they will break down.  It can be hard to find the recommended rate for adding eggshells as a pure soil amendment.  I did find a chart on Grow it Organically.com with some recommendations.  http://www.grow-it-organically.com/organic-calcium-sources.html - link to chart on organic calcium supplements for soil additions and recommended rates.  Eggshells are on the list.   
5. Pest Deterrent - Using crushed eggshells in and around plants is a wonderful way to cut down on slugs, snails, and any other mollusk type pests.  The sharp jagged edges of the shells are usually enough to deter them to other areas outside the garden where the pickings are easier for them to feed.  Between eggshells and beer, you can usually keep these pests at bay without the need for any chemical intervention.    



Rinsed and  heat drying
on the grill!

6. Feeding the Birds - Before and after laying eggs, mother birds need extra calcium in their diets.  To reduce the risk of transferring any salmonella to the birds, either boil your shells or bake them at 250 degrees Fahrenheit for ten to fifteen minutes.  Allow the shells to cool and then add them to your existing feeders.  Many times, I'll mix the shells with whatever I have out for the birds, but other times I like to place a small tray out by itself to watch the robins go wild when they're nesting.  They can't seem to get enough of them.  I've also read before that just mixing the gritty shell bits with birdseed will help all birds digest their food more easily. 

Green Meadows Healthy Garden Tip:

There is much information out there, as to whether or not raw eggshells pose a risk of contaminating the soil with salmonella.  According to Food Research International, salmonella, many other fungi, and bacterium's can live in the soil for extended periods and are most likely already present.  This we all pretty much know and by assuming good gardening and proper food hygiene practices, rarely will these bacterium's and fungi ever pose any type of threat.  However, the MSU Extension Service does site that any type of hot composting (temperatures of 140 - 160 degrees F) will kill the salmonella bacteria. 

As far as other uses for shells in the garden, recommendations vary and run from a general rinsing and drying to sanitizing for safety.  I'm always a little OCD and would rather error on the side of caution whenever using the shells.  If throwing them in the compost they are merely rinsed since I trust the process.  For all other uses in the garden, they are treated as if they were going to the birds.  I figure that if they are on top the soil as a pest deterrent and birds get into them, well I would hate for the potential to do any harm. I also go the extra length as a precaution since much of the foliar spraying happens when vegetables are producing on the plants.  This gives me the greatest comfort level of using them safely. 

Happy Gardening,

Denise, Beds 25 & 29