Funky Fridge? Make A Natural Fertiliser

I’m the sort of person that easily forgets certain leftovers and opened jars in the fridge. So of course things start to get a little funky. Instead of throwing things straight in the compost bin I try and take the time to make a natural fertiliser with some of the stinky fridge ingredients.

Biological fertiliser ready to use!

A natural or biological fertiliser is a liquid which contains living micro-organisms. The role of a bio-fertiliser is to improve micro-organism productivity and thus improve the soil. When applied to plants it aids in the growth and health of the plant and increases the availability of primary nutrients to plants.


Plants basically need 16 mineral elements to function at their optimum. The most important are nitrogen (N), phosphorus (P) and potassium (K). Maybe you know some farmers that add chemical fertilisers (NPK) to their garden. These fertilisers are synthetic, and can cause damage to the soil and the ground water, making them saline.

 So I like to use natural fertilisers as they are cheap to make, relatively easy and way less harmful to the soil and environment.


Fridge ingredients

In my fridge I found garlic, old funky kefir, bits of  chocolate, egg shells, old seaweed and dry herbs, which are all good to use in a biofertiliser. I also like to add animal (horse, cow or a touch of chicken) manure. Fresh manure should never be placed directly on your garden, as this may damage the plants and remove nutrients from the soil. This is why I use it in my bio-fertiliser or compost 😉 And finally add a few green leaves. Collect leaves from plants that have a deep tap root, such as dandelion, comfrey, parsley, some grasses, carrots and cabbage. These plants tend to break down easily and contain a good dose of nitrogen, and various other nutrients. 

Parsley, dandelion root (tap root) and comfrey


1. Place all the above ingredients in a 10L gallon. About half of the gallon is green leaves and other funky goodies.

2. Then fill the rest of the gallon with water.

3. Close the gallon and leave the solution in a cool place for 4-5 weeks until it starts to get brownish. Make sure it is out of children’s reach. My son thought it was very amusing to watch a whole gallon of biofertiliser tip on the ground.

4. Once ready, mix the biofertiliser with water in a watering can.
*Important: To use directly on the soil mix 10 parts of water to 1 part of biofertiliser. To use as a foliar spray,  20 parts of water to 1 part of biofertiliser. 
If you feel like you need to add more ingredients to your biofertiliser you can also try these:
Molasses (third boiling cycle in the sugar making process) provides an effective, available source of carbon energy and carbohydrates to feed and stimulate the growth of beneficial micro-organisms. The biodiversity in your soil will flourish and enhance the natural soil fertility. If you don’t have molasses then maybe try brown sugar or honey.
Fish bones are a good source of phosphorous. Dry out the bones in the sun then pound them with a pestle and mortar. Creating a thick pounder that you can add to your biofertiliser.
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Laila Helena is a BHSc Naturopath who has had a lifetime of sustainable living and Permaculture. She teaches people to be self-reliant and live consciously. The possibility of a sustainable planet has inspired her to create a business that works towards this sustainable future.

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