10 Simple Homemade Plant Fertilizers (Using Household Items)

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Did you know that around 40% of the soil worldwide is degraded? According to a 2022 report by the United Nations, soil depletion has become an increasingly serious problem in recent years.

As such, quality compost stands as a mandatory solution for your beautiful garden. It ensures that nutritious foods grow in high-quality soil.

Before you turn to chemical-grade fertilizers to achieve this, consider making your own by everyday, easy-to-obtain products—some of which you’re likely to have at home already! 

Read on for 10 DIY fertilizers that’ll grant you a backyard with fuller, healthier, and bigger plants and veggies.

10 Easy-to-Make Plant Fertilizers with Everyday (or Easy to Source) Items

1 – Coffee Grounds

Using coffee grounds in your soil isn’t as simple as some green and eco tips you might learn about online would have you believe. 

You see, used coffee grounds have had some of their acidity reduced to nearly neutral, sometimes lower, other times higher. It depends on the brand.

I know what you’re thinking: Aren’t coffee grounds too acidic to add to the soil? Won’t they steal the nutrients from the soil instead?

Yes, and that’s true for strong coffee grounds – not used ones. The latter is pH neutral and is what you’ll introduce to your soil or compost. 

Plus, you’ll only need a thin layer to start seeing results. Make sure to sparingly spread the grounds, too, so they don’t compact together.

In my experience, though, the safest way to use coffee grounds is to add it to your compost bin with other brown organic matter or to leaf mold. This way, you’ll be enriching the soil with nitrogen, phosphorus, potassium, and magnesium as well.

And their benefits don’t stop there! Coffee grounds are also good for repelling pests (see other methods in my post about getting rid of bugs on your plants) and encouraging earthworms into your garden soil.

But, Lisa, what if I don’t brew my own coffee and buy it instead from my local coffee store? No problem! You can get used coffee grounds from there – for free! 

That’s because it costs coffee houses more to get rid of used coffee grounds because if they’re not getting used, they go to landfill. From there, it emits methane; a greenhouse gas more harmful than carbon dioxide.

So, by using coffee grounds in your compost or adding it to your leafmould, you’re playing a part in reducing landfill waste, too. That’s a win all-round. Take it!

2 – Grass Clippings

As any green thumb would tell you: never throw away your grass clippings! They’re a superb source of nitrogen. Additionally, your soil will benefit from the added potassium, phosphorus, chlorophyll, and amino acids.

With that, here’s how to make fertilizer from grass clippings:

1. Fill a net bag with your grass clippings.
2. Place that in a large bucket. A five-gallon bucket or larger will do the job.
3. Fill with water and leave the clippings to steep. 
4. Let the grass clippings soak for a few days.

What will happen is the chemicals from the grass clippings will be released into the water. You can then use that water to feed your plants, then add the grass clippings to your compost pile.

And to make that compost effective, mix green material (the grass clippings) with brown. Then, balance that with carbon rich material for a good quality DIY compost. 

Cornell University has a good table of rich sources for both and guidance notes for using carbon and nitrogen ratios to make quality compost.

The nuts and bolts are:

For nitrogen rich sources, there’s grass clippings, the coffee grounds (mentioned above), and vegetable scraps. Manure’s listed too, but chances are, you don’t have that laying around your house. 

3 – Unflavored Gelatin

Did you know that those packets of gelatin in your kitchen cupboard are considered a nitrogen-rich fertilizer?

Well, believe it! Also keep in mind that gelatin will only be effective if it’s unflavored. Flavored gelatin has added sugars, which can be damaging to plants.

Here’s the story of how they discovered that gelatin is good for the soil:

Years ago, the Brand ‘Knox’ – a manufacturer of gelatin, had a theory that the product could be a rich source of nitrogen for plants. They had the University of Houston test this theory and see if they were onto something.

After two years experimenting on 49 species of plants, the study conclusively found that the gelatin does indeed provide a rich source of nitrogen to plants. Realizing their products have multiple uses, Knox now has a web page detailing different uses for gelatin—ranging from plant food to skin care.

The original Knox Gelatine is sold on Amazon.com. And while there are other manufacturers of unflavored gelatin, Knox is the product that’s been tested and proven to be beneficial when used as a fertilizer.

So, to make a batch of fertilizer, the manufacturer’s instructions are:

• To mix 1 pouch of Knox Unflavored Gelatine with 50 ml of cold water in a 1-liter jug
• Leave it for two minutes
• Add 250 ml of cold water and stir until it dissolves
• Then fill the jug up with cold water and water your plant with the mixture

Plants will only need this once per month. You can use it on both indoor and outdoor plants, too.

4 – Banana Peels

We all know bananas are a nutritious and healthy snack – but are you aware that even banana peels are a rich source of potassium and phosphorus?

Not going to lie, I was pleasantly surprised to learn about this! Studies have shown that banana peels have 42% potassium, up to 25% phosphorus, as well as additional calcium, magnesium and sulfur.

Nothing comes without downsides, though, and insects are the main problem with banana peels. As banana peels decompose and release nutrients in the soil, they become a hot spot for a bunch of insects.

Another more worrying problem is bees. They mistake the scent released as a defense hormone and will, thus, leave your plants alone. 

So, to use banana peels as a fertilizer, puree and soak them in water first. Use a sealed mason jar and keep them there for a week. After that, drain the solution with a sieve and use that water as a fertilizer.

With that, you can use banana peels how you want – whether in your potted plants or your garden. Alternatively, you can bake the peel and then grind it down to mix into your soil. The video below shows you how:

5 – Egg Shell Fertilizer

Now, the one thing that banana peels don’t have is nitrogen. To add that into the mix, you can throw eggshells into your compost. 

But, Lisa, eggshells?? How nutritious can those be?

Believe it or not, eggshells contain a few essential nutrients, mostly calcium, selenium, and nitrogen. To maximize on their benefits, you can add eggshells into your mulch—but a faster way to get the same benefits is to crush the eggshells up and boil them.

For this eggshell brew, you need a pot large enough to boil a gallon of water and just 30 grams of crushed eggshells. Boil the crushed eggshells for a few minutes, then leave them in the standing water with the lid on for a few days, then strain.

Little tip: If you’re using this on outdoor plants, leave the water in a sealed container outdoors so the water isn’t too hot for your plants that it shocks them.

6 – Wood Ash

Not many of you would have access to wood ash; but for those with a wood-burning stove or a fireplace, gather up that wood ash because it’s highly nutritious! Especially if you exclusively burn hardwood.

Let me tell you why: 

While the wood does contain nitrogen and sulfur – those are lost during the burning process since they’re released as gas. What remains in the ash is decent trace amounts of potassium, magnesium, and up to 25% calcium carbonate—which is an effective pH balancer for acidic soil.

That said, wood ash is only good for your garden when used in moderation. You don’t want a thick layer of this; just a light sprinkle over the top of the soil and it’ll eventually work its way down, adding the nutrients to your soil.

From experience, though, don’t use wood ash on potatoes as it can cause potato scabs.

7 – Cooking Water or Broth

Any food you boil, there’d be nutrients in the water. So, don’t toss it!

Just as you’d use the water from a netted bag of grass clippings as a fertilizer, and eggshell tea for the same, you can do the same with boiled foods. 

Recycle the water. Drain it into a separate container, let it cool, and then water your plants with that.

Naturally, the nutrients will differ depending on what you’ve boiled. Veggies, rice, eggs, pasta, potatoes, and spinach are all examples of foods you can consider. 

Remember not to add salt to the water, though!

8 – Consider Vermicomposting

Vermicomposting refers to creating a compost with the help of earthworms. The resulting compost is the most organic fertilizer a gardener could use.

To get started with vermicomposting, you need a worm bin. You can buy these online, or you can make your own. You’ll also need the right type of worms—particularly, red wigglers

Red wiggler worms will eat half their body weight every day. They eat vegetable scraps, fruits, paper, cardboard, potatoes (and the potato peelings), rice, coffee grounds, and cotton too.

To know how many red wiggler worms you need, weigh the garbage you throw out for composting. It’ll give you an indication of how many red wigglers you’ll need to start.

Interestingly too, red wigglers have both male and female organs. 

So what gender you get won’t matter, they’ll reproduce regardless. When they do, they’ll eat through more waste, creating your compost faster.

The real gem, though, is in their poop. Worm excrement is the richest fertilizer you can use on your crops. In agriculture, it’s known as black gold because it can fetch a good price from farmers in need of high-quality fertilizers.

Intrigued to learn more about vermicomposting? Some great resources include:

• A guide on Vermicomposting
• The Book: Worms Eat My Garbage by Mary Appelhof of Worm Woman Inc > WormWoman.com
• All about the Red Wiggler Composting Worm

Here’s a video overview of Vermicomposting as well:

9 – Weed Tea Fertilizer

Now hear me out; I know weeds are the envy of many a gardener, but they can all be put to a greater use.

For starters, weeds can be a great source of minerals and microbes that’ll help your crops grow faster, better, and healthier. I mean, think about it: they’re living and growing, so they have to be rich in nutrients.

As such, any weed you got would work. The best type, though? The weed of plants with deep roots, such as Dock Leaves and Dandelion. Since they dig deeper in the soil, they’re more nutritious. 

Weed-tea fertilizers also help increase your plants’ resistance to diseases and help deter insects from invading your plants.

With that, let’s see how you can make weed-tea fertilizer:

1. Harvest rainwater. If you’re going to use tap water, leave the water out for 24 hours to dechlorinate.
2. Extract nutrients by fermenting the weeds:
   • Pack the weeds into a bucket with a lid until the container is two-thirds full
   • Place a brick or rock on top of the weed pile to hold them down.
   • Pour in the water (the golden ratio: 1 part weed tea mixture to ten parts water)
   • Let ferment for a couple of weeks.
3. Use an old sheet or stocking to strain the water and prevent spreading weed seeds in your garden.

Wait! You’re not done, yet. Here are a few more things to keep in mind:

• Don’t close the lid too tightly during fermentation: Weed releases carbon dioxide as it ferments. If this gas isn’t able to escape, it can cause the lid to blow off explosively – potentially injuring anyone nearby.
• Be mindful of the smell: Weed-tea fertilizer has an awful smell. If you’re going to use the fertilizer for indoor plants, dilute the solution further to take away the smell.

For outdoor plants, leave the fertilizer somewhere in your garden that’s not too close to a window you open for fresh air. You don’t want this smell lingering in your home or near your patio when you’re having a picnic.

• Don’t use the fertilizer on harvesting crops: The taste and smells are likely to be rancid.

10 – Epsom Salt

Much like banana peels, Epsom salt is another unlikely homemade fertilizer for your garden. 

And we get it. That’s probably because Epsom salt can inhibit your garden’s ability to uptake calcium. Not only that, but it can also contaminate the water around your soil, increasing its mineral percentage.

So why are you suggesting we use Epsom salt as a fertilizer then, Lisa? Well, little do you know, but Epsom salt is a highly efficient fertilizer for plants, shrubs, and crops that struggle with a magnesium deficiency.

Sulfate is another mineral present in Epsom salt that a lot of plants could benefit from. It aids them in producing chlorophyll, for instance, and in staying alive longer.

Sold yet? Then, let’s see how you can use Epsom salt as a fertilizer:

• For potted plants: Dissolve 2 tablespoons of Epsom salt in a gallon of water. Spray your plants with this solution no more than once a month.
• For outdoor plants: Fill a tank sprayer with a ratio of 1 tablespoon of Epsom salt to a gallon of water. Use it once or twice per month.

As for which plants benefit most from Epsom salts; those include: roses, tomatoes, and peppers. Always test the soil beforehand, though, so you don’t kill your plants.

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