9 Ways To Make Garden Fertiliser At Home Using ‘Waste’

As many of you know, growing my own fruit and vegetables is a priority, and so is self-reliance and managing my waste in a closed loop system. So I want to share with you nine ways I turn different sources of ‘waste’ from around my home into valuable garden fertiliser with very little effort. There is no point buying fertilisers or sourcing different ingredients to make other fertilisers when I already have everything I need at home to manage the fertility of my gardens.

What are the benefits of homemade fertiliser?

• 100% organic
• No cost
• No packaging
• No environmental impacts from manufacturing chemicals and fertilisers
• No environmental impacts from the distribution of products and ingredients
• It’s an easy and satisfying way to create a more self sufficient garden and home
• They contain large amounts of beneficial soil organisms that commercial fertilisers lose during processing
• Nutrients are provided for your plants both directly and through improved microbial activity in the soil
• They help prevent soil and plant diseases.

How to make homemade fertiliser from waste

Let’s start with the most well known method of turning waste into fertiliser.

1. Compost

Compost is simply decayed organic matter like food scraps, clothing, paper, and some personal care products. It’s a great way to improve garden soil and provide nutrients for plants, and it might be all you need to fertilise your garden. Here are two posts about my composting methods, the first is how I compost at my new home, the second is how I composted at our previous home.

Why ‘Dig And Drop’ Composting And Free Range Worms Are For Me (And How To Do It)

Extreme Composting: for people who don’t like waste (and lists of don’ts)

2. Aquarium water

Aquarium water is filled with nutrients (nitrogen, phosphorus, potassium, ammonia) and micro-organisms from fish waste that plants can use. Our fish tank is filled with rainwater and only has two fish, so the nutrients are diluted enough to go straight on my plants or soil. This is a great option for watering indoor pot plants.

You won’t be able to use your aquarium water if you have a salt-water tank because the amount of salt may harm the plants. Also, if you’ve added any chemicals to the water, it’s advised not to apply the water to plants being grown for consumption.

3. Cooking water

Nutrients are released from food when it is cooked in water; this applies to all sorts of food including eggs, vegetables and pasta. Make sure you cool it before using as a fertiliser. Alternatively, you can do what I sometimes do, which is to pour the boiling hot water on weeds. The hot water will kill them and the nutrients will be available for other plants nearby.

4. Egg shells

We get about 7 eggs a day from our chickens so the egg shells quickly accumulate. Eggshells are about 95% calcium carbonate which is the same ingredient as lime, a popular soil amendment used to reduce soil acidity and improve fertility.

You can make a slow release calcium fertiliser simply by rinsing out the egg shells with water and drying them on a window sill to stop them growing mould. Once dry, grind the egg shells up in a blender or with a mortar and pestle. Store in a glass jar.

Read this next: Clean bottles with crushed egg shell

5. Wood ash

Wood ash straight from your fireplace, fire pit or wood fired oven is a good source of calcium (good for root growth), potassium  (improves disease resistance and flower, seed and fruit quality) and magnesium (important in photosynthesis), as well as other trace elements. However, the key elements nitrogen and sulphur are lost as gases during burning so it’s not a complete fertiliser.

Being 25% – 45% calcium carbonate, wood ash can be used instead of lime to reduce the acidity of the soil, so make sure you don’t use it around acid loving plants. Most vegetables like to be in the neutral pH zone so wood ash can help if your soils are slightly acidic which is most soils in Australia. You can also sprinkle wood ash in your compost from time to time as compost tends to be slightly acidic. Managing the pH levels of soils helps make nutrients available to plants.

The presence of potassium (5% – 7%) makes it ideal for top dressing fruiting plants and sprinkling throughout the vegetable garden when preparing beds.

If you are going to use wood ash, make sure you are only burning hard wood (best) or soft wood because treated pine, briquettes with chemicals added, and lighter fluid are not good for you or your plants.

6. Rabbit manure

My kids were given two rabbits to care for (one is a rescued rabbit) so we need to deal with their waste. Rabbit manure is rich in nitrogen and phosphorus and contains more nutrients than cow, horse and chicken manure, but it is a cold manure because the rabbit’s herbivorous diet means it contains an ideal ratio of nitrogen to carbon. This means it can be added directly to garden beds without it burning the plants. You can add the manure by top dressing or by work it through the top soil. Rabbit manure is great because the little bunny berries are dry, easy to handle, and odourless. They break down quickly and can be applied any time of the year, and of course you can add it to your compost too.

This Winter I have prepared my garden beds by working the rabbit manure and hay bedding through the soil. The bedding will contain rabbit urine which is high in ammonia, so letting that sit for a week to allow the ammonia to evaporate will stop plants from being burnt.

7. Chicken manure

Our chickens are free range but they still do 50% of their pooping while roosting at night in the hen house, so this needs to be regularly cleaned out. Chicken manure is considered ‘hot’ because it is high in nitrogen. It will burn plants if it is not aged or composted before being applied to the soil. As I use the dig and drop composting method and I want to avoid double handling, I age the straw and manure from the hen house on the garden bed I wish to plant in later on. After aging, I dig it through more thoroughly and continue with planting.

* I also have easy access to horse and cow manure from the neighbours which are excellent manures to use in the garden. If I ever find myself in a position of needing more fertiliser, this is a locally abundant resource I can tap into.

8. Weed tea

Making weed tea is a great way to deal with difficult weeds that you don’t want to put in your compost (so that they aren’t accidently spread around your garden). By making weed tea, you kill the weeds by drowning them in water and recycle the nutrients that have seeped out of the weeds back into the garden.

At the end of a day of weeding I stuff a bucket full of weeds, then submerge them completely in rainwater. If you only have access to mains water, it might be best to allow it to stand for 24 hours to allow the chlorine to disappear. The removal of chlorine makes it easier for microorganisms to multiply. Finally, I pop a lid on and leave the bucket in the garden shed.

After six weeks of fermenting, the weeds are completely dead and can be strained out of the solution. Beware, this stuff smells vile and will stick around for a day if you get it on you. The dead weeds can now be safely added to your compost to continue breaking down. Use the liquid, which will be rich in nutrients and beneficial microorganisms such as bacteria, fungi, protozoa and nematodes, as a fertiliser by mixing one litre with five litres of water.

Liquid fertilizer in the form of a “tea” is thought to give plants, especially vegetables and fruit trees, a boost that is quicker than applying the manure, worm castings or compost.

*Seaweed fertiliser

Although it’s not waste, if you live by the beach, a locally abundant resource for you to create a liquid fertiliser could be seaweed washed up on the shore. But, you must ensure you know the laws about collecting seaweed from beaches in your area. To make the fertiliser, use it in place of or in addition to weeds. As well as calcium, seaweed contains mannitol which is a compound that increases a plant’s ability to absorb nutrients in the soil.

9. Manure / compost tea or extract

Liquid fertilisers can be made by soaking any nutrient rich material like compost or manure in water. Often these are called ‘teas’, which they are if they have been brewed for a long time like the weed tea above. But according to Sustainable Gardening Australia an extract is a much quicker way of making a nutrient rich fertiliser but without the same level of microorganisms. 

To make an extract, simply put a shovel full of manure or compost in a 20 litre bucket, mix and leave for a few hours to 3 days. Strain off the liquid and use as fertiliser.

I’d love to hear if you have been able to turn other waste material from around your home into fertiliser for your garden. Please share in the comments.