Oyster Shell

oyster shellThere might be many more uses for your kitchen scraps than you realize.

Specifically, the empty oyster shells from your last seafood feast have some surprising benefits for your lawn and garden. It might seem like too much time and effort to turn these shells into a form that your plants can pull nutrients from, but the truth is that the process is easier than you expect. With just a little pre-planning and effort, you can add the nutrients of one of nature’s best forms of natural calcium and minerals right where the roots of your plants can take advantage of them.

What Are Oyster Shells?

As the name implies, oyster shells are the hard exoskeleton of a variety of molluscs that are in the family Ostreoidea. Most oysters live in saltwater or brackish environments. Additionally, their shells tend to contain high levels of calcium carbonate (about 96%). When oysters die in the ocean, their shells create reefs that are habitat space for dozens of other creatures. For this reason, they are considered a keystone species.

Oyster shells have plenty of benefits on land as well. When ground into a fine powder, they are a high quality soil additive due to their calcium and micronutrient content. Adding crushed shells to the soil produces a long lasting release of nutrients. This results in regulating pH levels and increasing the intake levels of fertilizer for your garden plants. Crushed shells also help to create habitat spaces for soil microbes in compost piles, which helps them to break down compost piles faster.

Where Can You Get Oyster Shell?

Crushed oyster shells can be bought from most landscaping supply companies. However, the quantities they are sold in means that getting enough shell for your lawn or garden might get expensive. There are other places to purchase them, here. Although, a better idea is to collect them yourself if you live near the ocean or simply contact a local seafood restaurant to see if they are willing to set you up with some of their daily shell garbage.

When you collect your own shells, be sure to wash and boil them before adding them to your soil. This is important since the sea salt that naturally gets encrusted on these shells can burn your plants if it builds up too much. After washing them thoroughly, you can break the shells into smaller pieces by covering them with a cloth and using a hammer to pound them into a powder.

How Does Oyster Shell Benefit the Soil and Crops?

There are plenty of ways that oyster shells are useful for your garden. Their calcium content helps to balance soil pH levels, improves nitrate uptake, aids enzyme formation and strengthens plant cell walls. If you’re growing leafy greens like lettuce and spinach or cruciferous vegetables like cabbage and broccoli, adding powdered oyster shell to your soil will make a big difference in your plants overall growth rates and vitality. The coarse texture of oyster shells also helps to reduce compaction in soil. And, it helps prevent potted plants from getting waterlogged by allowing water to run through the soil without getting trapped along the way.

As it turns out, oyster shell has plenty of advantages for your home besides the fertility of your garden. Because oyster shells are almost pure calcium carbonate, they make a useful supplement for poultry farmers that want their chickens to lay thick shelled eggs. You can also use oyster shells to keep garden pests away. When applied at the openings of their tunnels, the sharp shards and gritty texture also works as a deterrent in the soil to keep moles and voles far away from your plants.

General Application Rates

There are many different strategies for applying oyster shells to your garden. The best time of year to add oyster shell mulch is in the late spring or early summer when the soil has warmed up. Apply the crushed shells over your garden in thick layers, depending on how much you need. When used for garden plants, about four to six pounds per 100 square feet in ideal. Although when used as a mulch, layers about two inches thick are best.

After adding oyster shell to your soil, be sure to water it in thoroughly. This will allow the pieces to chemically interlock and become rooted in the soil so that they don’t blow away.

Making Oyster Shell Tea

Another smart strategy for using oyster shells is to brew them into a vinegar tea. Once you have crushed your shells, soak them in an apple cider vinegar mixture (one part shells to three parts vinegar) in order to pull out the calcium carbonate. After brewing for two to three weeks, you can mix a quarter cup of the mixture into a gallon of water and apply directly to your soil.

Composting Oyster Shells

Another method of getting garden benefits out of oyster shells is to use them in your compost. Not only will they balance the acidity levels in your soil, they will also create high quality habitat space for beneficial microbes. This will allow the microbes to eat through your pile and turn it into available and delicious soil nutrients.

Before adding oyster shells to your garden be sure to clean them thoroughly by boiling and then break them into small pieces that resemble crushed gravel. Add a layer of carbon materials like dry leaves and twigs and then add nitrogen material like grass clippings or food scraps. Next, add a layer of oyster shells to the top and cover them with a 2-inch layer of manure. You can create as many compost layers as you like. Additionally, water the mixture at least twice a week in order to keep it damp but not saturated. Sift the pile every few days to increase air circulation. Finally, add the entire mixture to your garden when individual pieces of shell or vegetables scrap can no longer be identified.




Additional Tips For Using Using Oyster Shells

Keep these suggestions in mind when using oyster shells in order to get the best results for your garden.

  • Shards of oyster shell can be incredibly sharp. This is why you should be sure to keep them far away from places where bare feet will be traveling!
  • Different forms of crabs, oysters and other sea creatures can have different levels of calcium in their shells. Therefore, don’t be afraid to work with a variety in order to learn what works best for your soil.