Home gardeners spend big bucks each year on organic fertilizers for their gardens and houseplants—but you don’t have to be one of them. You can easily make your own organic fertilizers at home, using waste material you are already generating and other inexpensive items.
Why Do Plants Need Fertilizer?
Your plants need fertilizer because:
- Most soil does not provide the essential nutrients that are required for the best plant growth and production.
- All of those beautiful flowers, fruits, and veggies that you grew last year took nutrients from the soil. Your garden needs another boost of nutrients to support this year’s plants. (This holds true even if you are super lucky to have the rich, loamy soil that all of us crave.)
Find Out What Your Plants Need by Getting to Know Your Soil
The first step to knowing what your plants really need in terms of fertilizer is knowing what your soil needs. That’s where a soil test comes in. Your local county extension office should be able to provide one. You simply send in a soil sample using the instructions they provide, and they’ll send you back an extensive report that tells you what your soil already contains and what you really need to add for optimal plant growth. (You can request that they provide their recommendations in terms of organic fertilizers.)
The report will also tell you the composition of your soil. Generally speaking, this is important because soils vary in their ability to hold nutrients and make them available to plants. Sandy soils do not hold nutrients well; clay soils do. However, clay soils do not like to give up the water they hold, so it is more difficult for plants to take up the nutrients that are available. As we mentioned above, loam is the soil that every gardener strives for. Those of us who don’t start out with it (and that’s most of us) try to achieve it by adding lots and lots of amendments—in the form of organic matter—to our soil over the years.
Which Do I Need: A Soil Amendment Or Organic Fertilizer?
First, let’s look at the difference between a soil amendment and organic fertilizer:
- Soil amendments are mixed with soil to improve its physical properties or increase microbial action. They make a plant’s roots happy and healthy. Amendments improve the soil’s water retention, permeability, drainage, air-holding capacity, and structure. Soil amendments are added to … well … the soil! You can add them before, during, or after planting.
- Organic fertilizers are applied to promote plant growth rather than to change the soil’s characteristics. However, many organic fertilizers also improve soil characteristics and thus can be classified as soil amendments. The nutrients in most organic fertilizers are not readily available for plants to take up. Microorganisms in the soil need to break them down further so that plants can use the nutrients in the organic fertilizer. However, some organic fertilizers—including bat guano, fish meal, and worm castings—do contain nutrients that are readily available to plants.
So, which does your garden soil need? The short answer is that you need both—amendments for long-term improvement of the physical properties of your soil and the microbial life in it, and organic fertilizers to meet your plants’ needs over the short-term growing season. The goal is eventually to need less and less fertilizer as the quality of your soil improves through the regular addition of amendments.
Organic Fertilizers vs. Chemical Fertilizers
Now let’s look at the difference between organic and chemical fertilizers.
Organic fertilizers rely on soil microorganisms, which break them down, making their nutrients readily available to the plants in the process. Organic fertilizer releases nutrients slowly and decreases the risk of over-fertilization. The slow release of nutrients also means they are available for a longer period of time. Even though they’re applied to promote plant growth rather than to improve soil characteristics, many organic fertilizers will also improve your soil. They may do so by increasing soil’s ability to hold water and nutrients, helping to loosen hard-packed soil, adding natural nutrients, and feeding important microbes.
On the downside, many organic fertilizers act slowly, so your plants won’t be able to use the nutrients until the decomposing process is completed. (Because of this, the best time to add organic fertilizer to your soil is before you plant in it.)
However, there are fast-acting organic fertilizers, too. Bat guano, fish meal, and worm castings all have nutrients readily available for plants.
In addition, while many organic fertilizers contain low percentages of the three key nutrients—nitrogen, phosphorus, and potassium (N-P-K)—they generally also provide additional nutrients you won’t find in chemical fertilizers.
Chemical fertilizers contain manmade materials, either completely or partially. Manufacturers combine these in different ways and amounts to get a super-growth fertilizer that may or may not be organic. Chemical fertilizers contain nutrients (usually N-P-K) that are already broken down and are therefore available to plants immediately. However, they do not improve soil characteristics.
It’s important to note that applying chemical fertilizers that your soil doesn’t need can lead to a buildup of salts and other minerals in the soil, causing damage to your plants.
35 Inexpensive Organic Fertilizers
When your garden is ready for organic fertilizer, here are 35 effective, affordable homemade options to consider:
- Worm Castings: Worm castings are soil superfood! They provide nitrogen and make soil absorbent. A huge number of beneficial microbes and bacteria are introduced to the soil, too. Learn more about worm composting here.
- Beer: The jury is out on this one. Many tests have shown that beer doesn’t add anything, but some people swear by it. Beer is a simple sugar and plants need complex sugars. Scientifically speaking, it probably doesn’t work. However, it does work to get rid of slugs and is a great cool-down on a hot gardening day! Also, if you brew your own beer or live near a microbrewery, you might want to use “Beer Mash” (the grains leftover from making beer). It’s a great soil amendment.
- Ammonia: Ammonia naturally occurs in the soil. There are microbes in the soil that pull nitrogen from the air and put it into the soil in the form of ammonia. The amount is what is important here. Use 1 or 2 ounces per gallon of water, mixed with molasses. Microbes love this stuff. If you’re uncomfortable using manmade ammonia, you can always slide down the list and use urine instead.
- Liquid Dish Soap: This is another one that is up for debate. There are a lot of studies that show that dish detergent (made with a lot of chemicals) is harmful to plants. However, there are some organic dish soaps that will help your “supertonic” to penetrate the soil. You only need a couple of drops in 32 ounces of water to get the job done. Remember, more is not better!
- Dog and Cat Food: Make sure that it is an organic pet food. Sprinkle the dry pet food on the bed or container. Turn the soil or water it in. It provides protein to feed the fungi and bacteria, nitrogen, phosphorus, potassium, and calcium, plus other minerals. To discourage vertebrae pests, be sure to cover this fertilizer with cardboard.
- Tea: Tea and tea bags are excellent for your garden. As the bag and tea decompose, they release nitrogen. First, make sure your tea bag is compostable. (You don’t want the ones made of polypropylene. If the bag is slippery, don’t use it in the garden.) Tea also makes a great brew for acid-loving plants like azaleas and blueberries. Tea also helps deter some root maggots.
- Bone Meal: Alright so this is a stretch for just having some lying around the house. However, bone meal is a really good source of phosphorus and protein. It is coarsely ground animal bones and waste products. (Make sure you need phosphorus in your soil before adding it. A soil test is your best friend in the garden.) If you want to make your own bone meal, here’s what you do:
- Collect bones by storing them in the freezer.
- Clean them by making a bone broth.
- Once they are clean, sterilize them. Place them on a baking sheet under the broiler for 10-15 minutes.
- Dry the bones by placing the cooking sheet on the counter for about three to four weeks. They need to be completely dry.
- Crush them into a fine powder with a food processor. (If you use a mortar and pestle, be sure to wear a mask over your nose and mouth.)
- It is now ready to use.
Read More: “How to Make and Use Bone Broth”
- Antacid Tablets: If your soil is low in calcium, this should be a go-to. It helps prevent blossom end rot in your tomatoes, peppers, and eggplants. Push one tablet into the soil by the plant’s roots. Voila! Instant calcium boost.
- Coconut Coir: Coconut coir has become the replacement for the non-renewable peat moss. This soil amendment adds air and space to assist with water retention and nutrient uptake. It makes a great seedling starter!
- Humanure: Okay, I hear you with your “ewww’s,” but hear me out. This organic material is a valuable resource rich in soil nutrients. In the US, each of us wastes more than a thousand pounds of humanure each year. Composting is key! Depending on your climate, it takes anywhere from 1 to 10 years to fully compost human feces and break down the pathogens. (To prevent the spread of pathogens and disease, only use for fruit and nut trees—not on vegetables.) Please consult a humanure expert in your area. For more information, check out The Humanure Handbook by Joseph Jenkins.
- Newspaper: Newspaper makes a great mulch and soil amendment. The added bonus is that the soy-based ink kills diseases in the soil. Newspaper can be shredded or laid in a thick layer on your beds. It is best to wet the newspaper before applying. NOTE: Do not use the glossy inserts from the paper. The colored inks and finishes can be toxic.
- Comfrey: This deep-rooted herb was once a traditional remedy to help heal broken bones. Its vast root system acts as an accumulator by extracting a wide range of nutrients from deep in your soil. These nutrients naturally accumulate in its fast-growing leaves. Cut 4 to 5 pounds (1.8 to 2.27 kg) of leaves from each plant. It is super-rich in nitrogen and potassium. Some research has shown that comfrey leaves have 2 to 3 times more potassium than farmyard manures!
- Urine: Yes, you read that right! Human urine is an excellent source of nitrogen. It is great to add to compost tea or your compost pile as an activator. Pathogens, disease, and toxins are quickly killed within 24 hours of leaving your body. Dilute the urine with water in a 1:2 ratio and water your plants.
- Citrus Rinds: Stir those rinds right into the soil. As they break down, they’ll release sulfur, magnesium, calcium, potassium, and more nutrients. You can also dry the peels and grind them into a fine powder that can be added to the soil.
- Kelp Meal or Seaweed: Kelp contains small amounts of nitrogen, potassium, and phosphorus, but it’s very high in trace elements, too. Typically, you’ll mix this liquid fertilizer with water. Use it as a foliar spray or pour it onto the soil around plants.
- Granite Dust: Granite is made of volcanic rock. It is filled with more than 60 different elements, including potassium, calcium, phosphorus, and magnesium. Trace elements in granite make the soil nutrient dense. Be sure to read the label!
- Green Manure: This is a favorite! Green manures are a fall cover crop that is grown on beds or pastures before or after crops or flowers to add nutrients back into the soil as they grow. They get turned under after their season. Some green manures include clovers, vetch, rye, and mustards.
- White Vinegar: Feed your container plants with a mixture of 1 tablespoon of vinegar and 1 tablespoon of sugar in 8 ounces of water. Bring the mix to a slow boil until the sugar dissolves. Then, let it cool and nourish those hungry plants. (There is a lot of chatter on the Internet about white vinegar changing the pH level of your soil. Tests have shown that it may have a temporary effect, but it is nearly impossible to change the pH of your soil, except over the very long-term.)
- Grass Clippings and Weeds: These are an excellent source of nitrogen and potassium for your fertilizer teas. Put the clippings in a 5-gallon bucket filled with water. Cover and let marinate for 3 to 4 weeks. You’ll have a lovely batch of “green” fertilizer tea.
- Mushrooms: The part of the mushroom that you see is actually the fruiting body. In the soil is where the real magic happens. Fungi are part of the soil web that helps bring nutrients to your plants.
- Borax: Some plants of the Brassica family, like broccoli and cauliflower, need boron (found in borax). Be sure to do a soil test to see if your soil needs boron. If it does, sprinkle 1 tablespoon over 100 linear feet.
- Bat Guano: Whether fresh or dry, bat poo adds a heavy dose of nitrogen to the soil. It acts fast and has very little odor. It also helps enrich the soil and helps with drainage and texture. Add it directly to the soil or make a bat guano tea!
- Rabbit Droppings: Bunny poo has a high concentration of nitrogen and phosphorus, as well as other trace minerals. It can be added directly into the soil or added to your compost pile. Bunny Poo Tea can be made using a 5-gallon bucket, a shovel full of rabbit pellets, and water to the top of the bucket. Let steep for 2 days. Water the soil when it’s ready! Watch our short video on raising your own colony of rabbits!
- Chicken Feathers: Feathers from your backyard chickens add nitrogen to your compost pile, and eventually, the garden. First, put them into your compost pile to let them decompose.
- Shellfish: Lobster, shrimp, and crab shells provide nutrients, including phosphorus. However, the bacteria that breaks them down is even more important! Simmer the shells for 20 to 30 minutes in boiling water. Drain well. Put them in a food dehydrator or oven until dry. Crush the shells with a mortar and pestle. Add to your compost pile or directly into the soil.
- Baking Soda: In order to sweeten tomatoes and discourage pests, lightly sprinkle baking soda on the soil.
- Compost: Compost is a great soil amendment and provides nutrients and microorganisms to your soil. The microorganisms make the nutrients available for the plants to take up. If you want to make a tea, let the diluted mixture sit for 12 to 24 hours with added aeration, by frequently stirring the mix or by using a water pump. The bacteria in the mix will explode in numbers, making it a very potent source of microorganisms. Click here to read more about boosting your compost pile.
- Alfalfa: Alfalfa is commonly used as part of livestock feed. However, alfalfa meal is simply ground up so that it breaks down faster. This particular fertilizer has low amounts of nitrogen, phosphorus, and potassium. As a result, alfalfa meal works fairly slow. The best use for this fertilizer is as a soil amendment in the early spring prior to planting crops.
- Nettles: The stinging hairs of the nettle plant may deter you from using this bad boy, but if you can stand it, put your harvest into a 5-gallon bucket, and cover them with water. In 3 to 4 weeks, you’ll have wonderful plant food for your garden.
- Hydrogen Peroxide: Your plants’ roots will thank you for a little extra oxygen. Mix 1 tablespoon of hydrogen peroxide with 2 cups of water. Water your plant’s roots with the solution.
- Pine Needles or Straw: Adding pine needles supplies nitrogen to your soil. It also adds bulk that will bring in the beneficial microbes to help break them down. NOTE: Too much straw or any other high-carbon “brown” material can rob your plants of nitrogen, because the bacteria will steal the nitrogen from the soil as it seeks a brown/green balance for the decomposition process.
- Blood Meal: Add crucial nutrients like phosphorus and nitrogen to the soil by using blood meal to promote healthy plant growth. Want to make your own blood meal? You can! Gather the blood. If you’re a woman, use your menstrual blood by collecting it in a menstrual cup. You can gather it from your meals, or from butchering some of your animals, too. Either way, pour the blood onto a baking sheet. Put it into a 375°F oven. Keep it in the oven until all the blood is completely dry, about 20 minutes. Let cool. Scrape the dried blood off the baking sheet and into a container. Use a mortar and pestle to ground the blood into a fine powder.
- Fish Emulsion: Fish emulsion fertilizer is high in nitrogen but pretty stinky! It is also very acidic and should be used lightly to avoid burning plants. Nonetheless, fish emulsion acts immediately once it is applied, which makes it a good treatment for leafy greens that are suffering from low nitrogen levels. Be sure to experiment. Some plants may not tolerate it very well. There is a recipe below!
- Crushed Oyster Shells: Oyster shells are a slow-release fertilizer to keep your garden healthy. Crushed oyster shells are a common supplement for chickens, and you can usually buy them where you would buy chicken feed. Or, if you have access to oyster shells, you can crush them into small pieces and bury them in the garden. The calcium carbonate in the shells will make the soil alkaline. Again, make sure you know your soil before adding this amendment.
- Nut Shells: Pop the nut in your mouth and toss the shell into the garden. It’s a win-win! Nut shells add bulk, which will allow water and nutrients to get to the plant roots. Microbes will be super happy with your discarded shells.
5 More Easy Homemade Fertilizers
#1: Comfrey Tea
Comfrey tea stinks like crazy, but it is oh-so-good for your plants! Here’s how to make it:
- In a big bucket or a lidded plastic trash can, submerge comfrey leaves for 3 to 5 weeks. (Use a brick or something similar to hold the comfrey leaves down.) How long you soak the leaves depends on the warmth of your climate.
- Mix the comfrey solution with more water to dilute (so it doesn’t damage or burn the root systems of plants), a 1:3 (water) ratio should work.
- Store in a cool dark place.
#2: Acid-Loving Plant Booster
Mix 1 tablespoon of white vinegar in 1 gallon of water. Hand water your acid-loving plants.
#3: Seed-Starting Fertilizer
This is a great fertilizer to use to keep soil moist when you’re sprouting seeds. Here’s how to make it:
1 drop of organic liquid dish soap
2 drops of ammonia
1 tablespoon of worm castings
Place the above into a 1-quart misting bottle. Fill it with water. Shake it gently and mist the soil in your seed container every day until you start to see little sprouts.
#4: Homemade Fish Emulsion
You don’t have to buy fish emulsion—you can make it at home! Click here to get the recipe.
#5: Container Garden Smoothie Fertilizer
Here’s a great fertilizer to use with the plants in your container garden:
Kitchen scraps (these might include egg shells; vegetable scraps; banana peel, broken into small pieces; used coffee grounds; used bulk herbs from herbal teas; spent fruit (non-moldy); stale sea-vegetables)
Place all scraps in blender. Fill blender halfway with water. Don’t add too much water, because there is already liquid in your kitchen scraps. (You don’t want your blender to explode compost all over the kitchen!) Place lid on blender. Start on a low setting and puree until everything is combined and becomes a liquid.
Feed it to your container soil. To do this, you can either pour it on top of the soil and water it in immediately, or you can let it sit for 24 hours, and then water it in or turn the soil. If you already have plants in place, pour the mixture into a large bucket and fill it with water. Then pour the water-liquid over the soil.
Remember, gardening is an adventure. Try different organic fertilizers and make note of the results. Some things may work better for you than others. You be the judge!
What Do You Think?
What’s your favorite organic fertilizer and how do you use it in your garden? Please let us know in the comments below!
This is an updated version of an article that was originally published on July 3, 2017.
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