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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Best Organic Fertilizer for herbs

natural fertilizer for herbs

For many of us, growing herbs is a passion. Using organic fertilizer for herbs helps us bring out the character and strength of flavor in our plants. Fertilizing herbs with a natural fertilizer is a powerful tool we can use to enhance the health-giving benefits of our herbs. 

In this article, we look at the best organic fertilizer for herbs, what herb plants need to grow, and explore whether homemade or store-bought organic fertilizer is better for your herb garden.

No matter what size garden you have, be it a balcony or a 10-acre plot, herbs are important for you. They make food taste better, smell amazing and have health benefits. Many types of herbs grow very well in pots. I have a huge garden and I still grow herbs in pots. Most herbs will take over the garden if you give them half a chance. 

What is the best organic fertilizer for herbs?

One that contains the essential macro and micro-nutrients your herbs need to grow. These are discussed below. Whether you make your own or purchase a ready-made one from the store depends on what you have access to.

Should you use organic or synthetic fertilizers for your herbs

There are many philosophical debates around the use of synthetic versus natural fertilizers. Synthetic fertilizers often provide quick wins – your plants look great very soon after adding fertilizers. They then provide a long-term crash. In other words, you will get lovely plants for a year or two, and then after that, you have to work hard to keep the plants healthy. The fertilizers just add nutrients, but nothing to go with it. Short-term gain, long-term pain.

Organic fertilizers tend to be formulated from substances that feed your soil – bone meal, feather meal, rock dust, and many other things which build your garden soil up. The idea is that we are growing plants in soil, not hydroponics – synthetic fertilizers often result in growing hydroponic plants in soil – the soil becomes so dead it does nothing but hold the roots. 

I try not to use inorganic fertilizer in my garden because I eat my herbs. Much like I do not enjoy synthetic colors in my food and drinks , I do not want synthetic compounds in my garden. Nature does its own thing, and we can work with it to our benefit.

spraying liquid fertilizer on herbs

Homemade or store-bought organic fertilizer

There are many natural fertilizers for herbs – many of these are made by fermenting fish waste, or seaweed, or a combination of these. Some are made from slow-release natural compounds such as bone meal and bird feather meal.

What type of fertilizer for herbs

Store-bought fertilizer comes as either granules or liquid. Slow-release or quick-release. The kind you choose depends on personal preference. 

Jobes organic all-purpose plant food is a great option if you want to buy an organic fertilizer online. 

Alternatively, look in the fertilizer section of your local gardening store. Look for an organic option and check for the following nutrients:

Main or Macro Nutrients

Nitrogen (N), Phosphate (P) Potassium (K). Optionally it won’t hurt if it also gives Magnesium (Mg), Calcium (Ca), and Sulphur (S).


Boron (B), Chlorine (CI), Copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Zinc (Zn), and Nickel (Ni). There are other micronutrients, but normally these are needed in such small quantities that they will be contaminants in any fertilizer of biological origin hence don’t worry about them at this stage.

Follow the dosage instructions on the bottle when mixing and adding natural fertilizers for your herbs. Despite these fertilizers being organic, you can still burn your herbs by adding too much.

There is a common misconception that a natural fertilizer cannot hurt a plant. This is not the case – natural substances can be just as poisonous as synthetic substances – think of a death cap mushroom or a snakebite. 

It is always good to start low and go slow with fertilizers – you can always add more fertilizer, but you cannot remove fertilizer once it is in the potting soil and your plant goes yellow.

What do herbs need to grow and taste delicious?

Herbs are plants that produce secondary metabolites – molecules that have a protective function to the plant. These tend to be flavor compounds that make a plant unappealing or even poisonous to pests. 

If we look at the biochemical pathways a herb plant uses to synthesize these compounds, we can see what the plant will need to boost its growth and metabolism.

Secondary metabolites in plants give flavor

Secondary metabolites are generally complex molecules and are made using several enzymes in different parts of the cell. These enzymes are often compartmentalized in special areas using membranes. If the enzymes roamed around freely in the cell they would cause endless chaos. So we know that we need enzymes and healthy membranes.

Enzymes that make the flavor and the importance of metal ions

Enzymes are complex protein structures that hold a chemical in a specific way. This allows the active section of the enzyme to act on the chemical substrate and transform it into something else. 

Normally these active parts of the enzyme have a metal ion, such as iron, copper, or manganese, coordinated into the structure of the metalloprotein enzyme. The main structure of the enzyme is made of amino acids, which are made from nitrogen compounds. 

We can now see that herbs need nitrogen, a mix of metal ions, and something that makes stable membranes.

The importance of Phosphate for cell membranes

Cell membranes are composed primarily of lipid bilayers. Lipid bilayers require phosphate. The rest of the membrane can be synthesized by plants themselves – assuming they have the starting materials to make enzymes.

How this affects what must be in our natural fertilizer

Our natural fertilizer for herbs needs to supply

  • nitrogen for amino acids to make enzymes,
  • metal ions so the enzymes can work and
  • phosphates to make more membranes.

Then our organic herbs can fill the membranes with enzymes to make secondary metabolites to make our herbs smell great.

Hence for an organic fertilizer for herbs to be useful, it needs to have a source of nitrogen, and traces of useful metal ions and phosphate. There are a lot of options. When I started gardening I used to buy pre-made Organic Fertilizers for my Herbs. Now I make my own.

fertilizer for herbs in containers

Best organic fertilizer for herbs in pots

Herbs in containers need more fertilizer than herbs growing in soil in a garden. This is because there are limited nutrients in the soil in the pot. Once the herb absorbs these nutrients it needs more. 

Also the roots are more confined in a pot. So you can fertilize herbs in containers every 2 weeks with an organic fertilizer. A slow-release liquid fertilizer at half strength is best. Just be careful not to over-fertilize as the essential oils that give the herbs their flavour and aroma may be diminished with over use of fertilizer.   

How to make organic fertilizer for herbs

You can make your own organic fertilizer using a variety of options including

  • Manure tea bag
  • Egg shells
  • Banana peels
  • Coffee grounds
  • Fish emulsion
  • Seaweed soup

To find out more about how I mix my own liquid fertilizer for herbs read this article on the best homemade fertilizer for herbs.

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Best Fertilizer For Herbs: What Is Most Beneficial

Bunch of various herbs in white bowl. Best fertilizer for herbs

What Is Fertilizer?

To know the best fertilizer for herbs, first you need to understand what fertilizer really is. We already know plants have basic needs including water, carbon dioxide, and sunlight. But how can we enhance the growth of our plants? The answer; fertilizer.
We need to know what fertilizer really is before we go and put it in the soil our herbs are growing in. Fertilizers are compounds put in the soil to promote growth in plants. The chemicals from fertilizers supply the soil with core nutrients to make it more fertile. So the best fertilizer for herbs would be ones that can deliver those compounds.

Looking deeper into the contents of fertilizers we can see the actual elements that are combined to promote growth. There is a multitude of elements that enhance the growth of plants. Hydrogen, carbon, and oxygen are supplied through the air and water existing around the plants. However, plants need more than these to add to the growth. Nitrogen, phosphorus, sulfur, potassium, and calcium are just a few of the elements that help maintain healthy growth.

The three main chemicals are nitrogen, phosphorus, and potassium. These elements are the building blocks of the cells in plants and are needed in the largest quantities.

  • Nitrogen is used for leaf growth and providing a healthy green color to the leaf.
  • Phosphorus develops new roots, seeds, and fruit. Further, it assists in fighting off diseases.
  • Potassium helps stems grow strong as well as speeding up growth.

How Fertilizer Helps Your Herbs Grow

To help ensure our herbs grow to the best of their ability we need to use fertilizer. Fertilizing your herbs once every 3-6 months will maintain healthy growth. You may notice after planting your herbs that they begin to dry out or wilt after a month or so, this means you may need to fertilize more often to supply the soil with the nutrients it is missing. Applying a good fish and kelp fertilizer at half the strength for a few weeks will help the herbs get back on track with their growth.

Healthy looking mint plant.

If you are like many people and have your herbs planted in pots or boxes, you may find that your herbs are becoming dry and wilting more than you had hoped. This is a result of the nutrients from the soil being lost through drainage holes after you water them. It is recommended that you use supplementary fertilizers to assist with this issue.

There Are Two Types Of Fertilizer To Choose From; Liquid Or Granule.

Firstly, liquid fertilizers. These can be absorbed quickly and provide herbs with a quick boost of the nutrients they are lacking. Liquid fertilizers however often need to be applied more regularly to maintain their function in healthy growth. To apply, mix the recommended amount of fertilizer in with water and slowly poor at the base of the plants.

The second option is a granule fertilizer. Granules release the nutrients over time and as a result effectively feed the herbs for longer. However, the granules do not allow immediate absorption into the soil or roots. To apply, sprinkle the recommended amount at the base of plants and either using your hand or a hand rake mix in with soil being careful not to disrupt roots.

What Fertilizer Should You Use For Your Herbs?

The best fertilizer for herbs would be a 5-10-5 mix. That is 5% Nitrogen, 10% Phosphorus and 5% potassium. This is a good general fertilizer for all herbs. To know for sure what your soil is missing, it is recommended that you complete a soil test. These are provided in a test kit form, they are then sent to the lab to tell you exactly what you need for your garden to thrive.

What Else Affects The Fertility Of Soil?

Soil pH levels are another important aspect of fertility, so buying a pH tester is also recommended. As a rule of thumb a pH level of 6 to 7.5 is ideal for herb growing. To raise pH level apply some lime juice and to lower pH level apply some sulfur.

Thank you for taking the time to read this article. I hope you are now aware of the bezt fertilizer for herbs so your garden is able to thrive.

Feel free to check out our other growing guides