How to Make Fertilizer from Kitchen Waste: A Complete Guide

Fertilizing your garden is paramount if you want to grow bigger blooms and healthier plants. However, quality organic fertilizer can dig a serious hole in your budget. Alternatively, you could use chemical fertilizer and call it a day or make organic fertilizer from kitchen waste.

Turning food waste into fertilizer is easier than you think. You can turn almost all kitchen scraps into compost by piling up food waste and mixing it with sawdust, grass clippings, or garden waste. Alternatively, you can fertilize individual plants by burying kitchen scraps near the plant’s roots.

Is Kitchen Waste Good for Plants?

Yes, almost all kitchen waste is good for plants. Rotten fruits, fruit peels or cores, eggshells, nutshells, coffee grounds, and paper tea bags are excellent composting materials. Many people advise against composting bones, meat products, and dairy, but this doesn’t mean they are bad for your plants. 

For instance, you can dry chicken bones left from your dinner and smash them into bone meal. Bone meal is an incredible soil nutrient most plants love.

You may not want to add meat or dairy scraps to your compost pile, but you can still use this organic matter as fertilizer. 

For instance, you could use this waste to make liquid fertilizer or bury the meat and animal carcasses about 2-3 feet deep into the ground. Wait for a month or two, then seed your flowers or vegetables – the soil will be naturally fertilized.

What Food Scraps Can You Compost?

Composting is easy and eco-friendly, but can all kitchen waste go into your compost pile? The answer is no. You can only compost organic matter, and even then, not all scraps are suitable. So, here’s a list of food scraps, and other kitchen waste, that you can compost.

Fruits and Vegetables 

You can compost fruits and vegetables in any form, including fruit and vegetable cores, peels, rotten fruits and vegs, seeds, etc. Throw them in the compost pile fresh or cooked. Fruit and veggies turn into nutrient-rich organic matter that can feed flowers and edibles alike.

Eggs and Egg Shells

Eggs contain many vitamins and healthy nutrients that will help grow happier plants. Raw eggs could theoretically go into the compost pile, but if you’re worried about bad smells, you can only use cooked eggs, boiled or fried. 

Eggshells don’t have to be cooked beforehand. You could crush them or add them whole, as they’ll break down as you turn the compost pile anyway. Eggshells contain calcium, which is an important nutrient for plants like tomatoes, peppers, and eggplants.

Cooked Food and Leftovers

Like fruits and vegetables, cooked food and leftovers turn into essential nutrients, such as nitrogen, phosphorus, and potassium. You can compost virtually any cooked food, including soups, stews, rice, bread, casseroles, sauces, and so on.

Cooked Meats and Bones 

While we mentioned cooked food above, cooked meat and bones get a special mention. That’s because many people advise against throwing these products in your compost pile.

The main reason some people say you shouldn’t use them is that they attract pests. However, all you have to do is bury them in the middle of your pile to prevent the issue. Bad smells could also be a concern, but again, burying meat and bones deep into the pile will prevent offending odors from spreading.

Old Herbs (and Other Natural Plant Material)

Did you attempt to grow herbs in your kitchen and end up with a pot of dried thyme or basil? Don’t throw them in the trash. As long as these plants don’t have any signs of disease or seeds, you can use them for compost. The same goes for all other dead houseplants you might have.

However, never compost natural plants that have signs of disease. Fungi and bacteria that infect plants won’t die as the plant decomposes and could affect your flowers or edibles as you use the compost to fertilize them. 

Coffee Grounds and Tea

Coffee grounds, infused loose tea leaves, as well as paper tea bags, are also compostable. This organic matter is suitable for ornamental plants that need more acidic soil, such as roses, rhododendrons, hydrangea, lilies, and azaleas. In the vegetable garden, coffee grounds and loose tea leaves go hand in hand with carrots, radishes, cabbage, and blueberries. 

Dairy Products 

Like meat and bones, dairy products are a sort of black sheep of composting. However, you can compost leftover cheese, milk, and yogurt if you want to. Mix these products with other organic materials such as dry leaves or grass clippings, then bury them deep into the compost pile to prevent attracting pests.

Cooking Oil and Other Fats 

As a general rule, oil and fats will slow down the composting process. That said, you can still compost small quantities of cooking oil or bacon grease, for example. If you’re dealing with a full pan of oil, though, you should discard it in the trash.

Paper Products 

Foods aside, your kitchen produces other organic waste. Think about paper towels, paper cups, and plates, as well as unwanted mail, newspaper, and other recyclable paper products. All of them can go into the compost pile. However, never compost glossy paper, such as the one used for magazines, because the inks on it could be toxic.

How to Make Organic Fertilizers from Kitchen Waste 

Compost piles are often associated with grime and revolting smells. However, anyone can make compost at home (whether you have a garden or small balcony) in about 40 days and with no smell at all. Here’s how. 

Step 1 – Prepare a compost bin

When thinking about making compost, many homeowners envision a pile of decaying scraps tucked somewhere in a corner of the yard. However, you don’t have to keep the compost pile on display – it is quite unflattering to look at, after all.

Get a compost bin, or make one yourself. An old plastic bucket could suffice if you don’t have lots of space. Drill some holes in it to allow air to circulate and cover it with a suitable lid to keep pests, such as rodents, away.

Step 2 – Add kitchen waste to the container

When clearing your pots, pans, and plates, separate the compostable scraps from all other kitchen waste and add them to the compost bin when cleaning the kitchen. As a rule of thumb, decomposition is faster if you cut or shred the material into small pieces. If you don’t mind waiting for a longer time, you can add larger chunks. 

Step 3 – Add some brown matter

For composting purposes, organic matter is divided into brown and green. The green category includes mostly wet or recently growing materials, like food scraps, grass clippings, coffee grounds, and recently pulled weeds. 

Brown matter contains dry leaves, sawdust, wood chips, corn stalks, but also paper material like napkins, paper towels, newspapers, bills, and letters.

While green matter provides the most nutrients for the plants, brown matter allows air to better get into the pile and also adds carbon to the compost. Thus, once you’ve added the kitchen waste, cover it with a layer of any brown materials you have at hand.

As a general rule, you should alternate the green and brown layers in your pile.

Step 4 – Add some microbes 

If you’ve paid attention to the biology class, perhaps you know that organic matter decomposes thanks to microorganisms. They grow on their own on decaying organic matter, but you can speed up the composting process by adding them yourself.

You could either use semi-done compost and mix it into the new pile or add manure. Dairy products can also help start a microbial colony.

Step 5 – Aerate your compost

Oxygen is crucial for aerobic composting, and the holes you’ve drilled into the bin are not enough to ensure proper airflow. That’s why you should turn the compost pile regularly, typically every three to four days for 40-45 days. You could turn the compost with your hands (wearing rubber gloves) if the pile is small or use a shovel for a larger pile.

Step 6 – Repeat steps 1 to 5

Aerobic composting will prepare organic fertilizer in about 45 days. You can keep adding food scraps and brown matter to your compost pile until the bin is full, then you can start another compost bin. 

Your compost is ready to use when the organic matter in your bin has a crumbly texture and rich, earthy smell.

FAQs: Food Waste to Fertilizers

What is the best homemade fertilizer?

Compost is by far the best homemade fertilizer, ideal for edibles and ornamental plants alike. Compost is also suitable to use in orchards and large-scale organic farming. 

If you don’t feel like making compost, here are a few things you can use to fertilize your garden soil: 

  • Banana peels 
  • Coffee grounds
  • Aquarium water (freshwater only)
  • Epsom salt
  • Wood ashes from your fireplace or fire pit
  • Human hair (from your hairbrush or the barbershop)
  • Horse feed 
  • New or used matches 
  • Powdered milk

What natural fertilizer makes flowers?

Compost tea is an excellent fertilizer for flowers. Fill a sack with compost and place it in a plastic container, then add water. The ratio should be one part compost to five parts water. Cover the bucket with a lid and let the tea brew for about ten days. Transfer the liquid into a garden pump spray once it achieves a tea-like color and use it as a foliar fertilizer.

Manure tea, made in a similar way but using manure instead of compost, and chicken waste are other excellent fertilizers for flowers.

What animal poop is best to make liquid fertilizer?

Rabbit waste is the most prized animal poop for making liquid fertilizer. Since rabbit manure is difficult to come by, cow manure is the second best, but you could also use goat, sheep, or chicken manure. However, never use dog or cat waste because the high concentration of protein in their waste can be detrimental to your plants.

Key Points

Compost is an organic fertilizer that helps you grow healthy plants with minimal investment. All you need is a compost bin and a small outdoor area to make it – even a tiny balcony works. Alternatively, you can get an indoor compost bin or automatic kitchen composter to turn food scraps into a nutrient-rich and eco-friendly fertilizer.

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