How to make fertilizer from kitchen waste?

fruit peel fertilizer

Are you chucking out food scraps from your kitchen that you can use as free fertilizer for your herbs? There are many simple ways we can make fertilizer from kitchen waste that can be used for our herb garden. Coffee grounds, eggshells, banana peels and fruit peel can all be used to make the easiest fertilizer for your herbs.

Kitchen waste

1.3 billion tonnes of food gets wasted in the world every year according to the UN environment programme. This is one-third of the amount produced. When this food waste goes into landfill it creates greenhouse gases contributing to global warming. 

If our kitchen waste can be diverted from landfill and instead be used to create an organic fertilizer for our garden this is so much more sustainable for our planet. You can add your food scraps to a compost pile or even make your own liquid fertilizer.

Fruit peel fertilizer

Do you want to create your own fruit peel compost and fertilizer for your plants? It’s a great way to save money, be environmentally friendly, and have some fun! You can do it yourself with just a few simple steps. I’ll show you how below.

First, what you’ll need: 

– fruit (any kind) 

– a compost bin or container with holes in the bottom for drainage and aeration. You can also use a trashcan if it has these features. 

– water source to help break down the peels faster. This could be kitchen faucets, hoses, or fountains.

– compost starter such as manure, coffee grounds, and/or worm castings 

– a shovel for mixing the peels with soil and other ingredients to help speed up the decomposition process. You can also use your hands if you don’t have this available! It just might get messy. 🙂 

Now that you have your supplies gathered, it’s time to get started.

– Remove all stems and leaves from the fruit or peel 

– After peeling the whole fruit, cut it up into smaller pieces so they can fit in a compost bin easier. 

– Follow instructions for your type of container on how to mix and layer the items. 

– Take your compost out to where you want it added daily or weekly, break up with a shovel, and leave for about six weeks (or longer if needed). 

If done correctly, this is an easy step-by-step process that can make beautiful frugal fertilizer in no time at all!

kitchen waste fertilizer from fruit peel

Are coffee grounds good fertilizer for herbs?

Yes! Coffee grounds are a rich source of nitrogen at about 2% by mass nitrogen. I outlined in this article on the best fertilizer for herbs why nitrogen is important for herbs. 

To compare, cow manure, depending on whose analysis you read, has between 1 and 3% nitrogen. 

Coffee grounds also contain significant amounts of potassium, phosphate and minor trace elements such as zinc. 

After we make our morning coffee the coffee grounds are normally thrown away with kitchen waste. These however represent an excellent material with which to make organic fertilizer for our herbs. This ground coffee can just be hand sprinkled over your garden or added to your worm farm or compost pile..

Benefits of adding coffee grounds to soil

If we look at soil, it is a complex ever-changing mixture. The organic matter, if it can be broken down, is eaten by different fungi and microbes to the point where eventually there is very little of it left. Only the nutrients. The carbon all gets turned into carbon dioxide and goes back into the carbon cycle.

However – if organic matter is burnt, some of the organic compounds in the matter get turned into “charcoal” like compounds that cannot be broken down by bacteria. Others get turned into humic substances which are similar. 

Coffee grounds contain considerable quantities of these compounds which add to your stored soil carbon. Soil carbon is very very important for the overall quality of your soil as it helps give soil structure, stores water and nutrients that plants need and feeds beneficial microbes.

fertilizer from kitchen waste

Why eggshells make good fertilizer for herbs

Eggshells are a great source of calcium, being composed almost entirely of calcium carbonate. Calcium is needed in cell walls and membranes for structural roles in plants. Calcium carbonate is not soluble, hence we need to find a way to make it available to plants.

How do you fertilize plants with eggshells?

Calcium can be extracted from eggshells by increasing the surface area and then letting it decompose. The surface area can be increased by making crushed eggshells and then allowing this eggshell powder to decompose by the beneficial bacteria and microbes in the garden. 

Dry the eggshells out on a baking sheet in your oven
Crush the eggshells with your hand or blitz them in a blender or thermomix to make ground eggshell. 
Sprinkle this natural fertilizer over your hot compost or mulch.

Why banana peel makes good fertilizer for herbs

Banana skins are a minor source of potassium. I have had many people over the years tell me that banana skins are rich in potassium – I cannot find a single scientific paper to prove this. It appears to be a self-repeating urban legend.

Banana skins are however an excellent scaffold for microbes to grow on, and these microbes will break down other parts of the compost mixture to make minerals bioavailable.

How to use banana peels as fertilizer for herbs

The easiest way to use your banana peels is to:

  • let them soak in a jar of water for a few days and then 
  • pour this water around the base of your herbs. 

If you have a worm compost you can:

  • Chop up the banana peel to increase the surface area then
  • Add to this your worm farm

If you’re feeling adventurous you can also make a homemade fertilizer using your banana peels, coffee grounds and eggshells. I have shared a recipe below for organic liquid fertilizer. 

How to use banana peels as fertilizer for herbs
Photo by SHVETS production from Pexels

How to make organic liquid fertilizer from kitchen waste

  • Place all of your coffee grounds, eggshells and banana peels in a 5 gallon bucket each day and close the lid.

There is no rush here – the whole mixture will start to compost in the bucket. 

  • Place a few handfuls of good quality potting soil in the bucket. This is a source of microbes that can assist in the composting process.
  • When your bucket is half full, take a small garden spade/shovel and dig downwards into the bucket to break up all the egg shells. I normally crush these with my hands before placing them in the bucket, and this helps to break them up more.

This will also compact the mixture downwards. When the bucket is genuinely half full, you are ready to make fertilizer. 

Adding Molasses and Kombucha

  • Place two cups of black strap molasses in the bucket and a cup of kombucha. The mixture is now full of all sorts of beneficial microbes.

Molasses provides a source of sugars to drive the fermentation which will make the minerals bioavailable to our plants.

Kombucha contains acids that will dissolve the calcium carbonate in the egg shells, and also help to make some of the nutrients in the coffee available.

  • Make a small hole in the lid of the bucket, and put a small fish tank aeration pump such as this on the lid of the bucket and place the hose through the hole. Put the airstone on the end of the hose and allow the pump to aerate the mixture.

The small is quite mysterious – every time I do this the mixture has a different smell. One time it smelt really bad. Another time there was an amazing raspberry smell and we actually left the bucket in the house as it smelt so good.

Generally, it is a good idea to start the process off outside, or on a balcony, and if the smell is not bad, you can make a call after that. 

  • If it is cold, place a small fish tank heater in the bucket and set it at about 75°F. The heater will allow microbial life to flourish.
  • Allow the process to run for at least two weeks. If necessary, top the water level up as some will evaporate with the aeration.

Filtering your liquid fertilizer from kitchen waste

  • Place an old pillowcase in a bucket, pour the liquid into the pillowcase, and all the gunk and sludge in the reactor bucket. 
  • Tie the pillowcase off with a rope and hang it above the bucket – the liquid will drain out into the bucket overnight. 

The filtered product is ready for application. The gunk in the bag – I use this as fertilizer too and make small holes in my pot plants and just scoop the stuff into the holes and bury it.

Application of your homemade herb fertilizer

This fertilizer can be quite hot – in other words it can have quite a high nitrogen content derived mainly from the coffee grounds. There are many beneficial microbes in the mixture that can help to establish a healthy microbial ecosystem on the leaves, as well as benefit the roots.

  • Dilute a cup of this liquid fertilizer in a one-gallon watering can. Fill it to the top with water.
  • Apply this to your plants on the leaves and into the soil. 

This floods the soil with beneficial microbes. You will see a week from watering, your plants just look healthier.

  • Apply once a month. This is best applied fresh. 

The microbes will become inactive with time, hence it has a shelf life, and rather make, bulk dose all your plants, and then start another batch.

By diverting your kitchen waste from the garbage and landfill to your garden you can save money by not having to purchase fertilizer and it is also better for the planet. You’ll also know exactly what is in the fertilizer rather than having to use a synthetic fertilizer. A natural fertilizer is always best. 

Making your own fertilizer from kitchen waste is so easy and beneficial for all.  

Read more>> Best organic fertilizer for herbs

For other fertilizer recipes you can make at home have a look at this article on the best homemade fertilizer for herbs. 

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