Using Crab Shells In Compost- A Detailed Guide

Sharing is caring!

Last Updated on April 1, 2022

Are you aware that your crab shell doesn’t have to go to waste because you can make use of crab shells in your compost? Yes! Those leftover crab shells can be put to good use in your garden. Crab shells in compost can be pretty beneficial to your plants.

Crab shells will fine alongside other types of shellfish. So, you can easily add crab shells to your compost pile because they are quite biodegradable. Even though it may take some time for these shells to biodegrade, you can also crush them just to hasten up the process.

Crab shells in compost can enrich your compost because they are loaded with good nutrients to help your plant develop.

If you wish to learn how to compost crab shells, then we’ve got you covered here. Read on to find out about using crab shells in your garden and turn those leftover crabs into rich fertilizer for your plants.

Crab Shells In Compost

It is very possible to compost crab shells. Crab shells in compost are an easy thing to do so far you get the right knowledge.

Crab shells are made up of calcium carbonate and chitin (a type of carbohydrate).

Crab Shells In Compost

How To Compost Crab Shells: A Detailed Guide

Follow the steps below to learn how to compost crab shells:

Step 1- Cleaning Of The Shell Crab

Clean the shell of your crab just to eliminate any salt or other foodstuffs you don’t want in your compost.

Generally, seafood such as crab contains a high level of salt. Although the presence of salt isn’t so toxic to the compost, however, it is not so beneficial to your compost. But the excess amount of salt can be harmful to beneficial worms or another vermiculture setups.

Again, the crab shells are safe to be composted. However, the fat and meat are not so safe. This is mainly because they may throw off the balance of your compost pile and this may give rise to an unpleasant odor or even invite pests to your plant when you use this compost.

Read more about Zucchini Plant Not Producing: 4 Common Reasons?

Step 2- The Shell Of The Crab Should Be Crushed

Usually, crab shell tends to take a long time to decompose compared to other compostable materials. Hence, when you crush the crab shell into tiny bits, then it can hasten up the breakdown of the compost pile.

If you are however wondering how to grind or crush your crab shell, you can simply use a hammer to crush them into bits. But if you wish to skip this process, you can. Your compost will just be taking a while longer to decompose.

Step 3- Crab Shells Can Be Distributed Throughout Your Compost

After crushing the crab shell into tiny bits, it may not be enough. You may still need to mix the pieces into existing compost instead of allowing the crab shell to sit in large compost.

Step 4- A Balanced Compost Heap Should Be Maintained

A healthy compost can’t be simply created from just one material. If you want a good result, you can pair crab shells with other compostable kitchen scraps. A bonus tip is to add a carbon-rich material such as dead leaves, grasses, woodchips, or cardboard.

Step 5- Composting – Crab Shells In Compost

Turn the compost mixture using a pitchfork or spade. Ensure you change the layers of the compost pile so it can supply oxygen to the microbes that are responsible for decomposing the organic mixture. Doing this will give rise to heat and the compost temperature can go as high as 160 degrees Fahrenheit.

Make sure you also add water to the organic mixture of the compost pile. If moisture isn’t present, the microbes won’t be able to decompose the organic matter and you may not get the ideal compost result. However, ensure the water is minimal because adding too much water can make the compost turn out to be smelly and squishy.

Additionally, you can poke some holes in the compost pile just to allow air to go inside the compost and enhance decomposition.

Down to Earth Organic Crab Meal Fertilizer Mix 4-3-0, 5 lb

Step 5- Monitoring – Crab Shells In Compost

Finally, continuous monitoring or checking your compost pile daily just to keep tabs on the moisture because adequate moisture is also crucial for easy and fast decomposition.

Check Out How Deep To Plant Lettuce- The Ideal Planting Depth

Benefits Of Composting Crab Shells

Crab shell compost is rich in nutrients that your plants can benefit from and a good number of plants can benefit from crab shell compost. Below is some awesome nutrient crab shells can offer your plant:

  • Calcium

The shells of crabs are particularly rich in calcium. Now plants depend on calcium to produce strong cell walls and combat many common plant diseases.

  • Magnesium

Regarding photosynthesis, it cannot take place if magnesium is absent. Crab shells naturally contain magnesium. So, they can be an alternative to the magnesium-containing fertilizer that you may find at your local garden store.

  • Phosphorous

Phosphorous helps and serves as a building block to a plant’s life. Genetic reproduction as well as photosynthesis needs phosphorous to aid their process. So, crab shell is a good source of phosphate that your plant can benefit from.

Benefits Of Composting Crab Shells - Phosphorous
  • Chitin

Phosphorous, calcium, and magnesium are all important for the proper development and healthy growth of your plant, and crab shell contains these essential nutrients. But apart from these nutrients, the crab shell is also rich in chitin.

Chitin enhances the growth of certain beneficial bacteria and enzymes. Now, these bacteria and enzymes help to wade off organisms that are harmful such as nematodes, fungi, and soil-borne insects.

Conclusion On Crab Shells In Compost

Crab shells in compost can be an excellent addition to your compost pile because they are loaded with good nutrients that can help your plant grow. This crab shell is rich in essential nutrients such as phosphorous, magnesium, and calcium. It is also rich in chitin.


Are crab shells good for garden?

Yes. Crab shells are good for garden. Even if you do not have a compost pile to mix the crab shell, you can simply put these shells directly into your garden.

Can you put seafood shells in compost?

Yes. You can put seafood shells in your compost and let your plant enjoy the benefits they offer. They are loaded with calcium as well as other crucial micronutrients needed by plants.

Are crab shells good for fertilizer?

Certainly, crab shells are good for fertilizer s because of the benefits of adding some essential nutrients to plants. Crab shells even offer extra benefits that cannot be found in other types of fertilizers such as chitin. This chitin present in crab enhances the growth of chitin-eating bacteria.

Does crab shell decompose?

Yes, crab shells can decompose. However, the rate at which they decompose can be slow or a bit fast depending on their state. If you crush or break crab shells into pieces before composting, then the decomposition can be hastened up. But if the crab is not crushed, the decomposition can be pretty slow.

Sharing is caring!