Make Your Own Fertilizer: A DIY Guide

Depending on the rate of application and the size of your vegetable garden, you may find yourself purchasing large quantities of fertilizer. But before you head to the garden center, did you know that there are plenty of fertilizer recipes—regular and organic—that you can make at home? And believe it or not, some of them are reasonable to make yourself. 

Types of fertilizer

Regular (also known as chemical, conventional, or synthetic) fertilizers will supply necessary nutrients to plants, but they are not as beneficial to the soil itself. In fact, over time synthetic fertilizers may even harm soil quality by reducing the growth of microbes or overwhelming soil with acid or salt.

Organic fertilizers are created from organic ingredients and should not be confused with “all-natural” fertilizer, which can include non-organic materials that are considered “safe” for organic gardening since they are not synthesized. Organic fertilizers encourage soil microbes, earthworms, and other flora more so than synthetic fertilizers do.

All may come in granular or liquid formula: granular fertilizer will last 1-9 months (check the packaging), while liquid will last only 1-2 weeks. Granular fertilizer can also come in a “slow-release” formula that will release a steady flow of nutrients over 2-9 months due to a special coating. Previously just synthetic fertilizer was available as a slow-release formula, but products that use organic coating are popping up. These release nutrients as the coating decomposes.

Organic fertilizer recipes

Beginner gardeners can easily create these organic recipes; organic ingredients are safe when mixed together and more accessible than those used in regular fertilizer recipes.

Add your choice of ingredient to a 5-gallon bucket and strain after steeping for three days. Use no more than once every two weeks:

1/3 bucket  of dried chicken manure with wood shavings (dilute 1:1 with water)
1/3 bucket of seaweed
2/3 bucket of fresh grass clippings (dilute 1:1 with water)
Urine can be used immediately after diluting 1:20 with water

To ensure a 1-2-1 mix of essential nutrients Nitrogen-Phosphorous-Potassium, try this mixture:

2 parts blood meal
2 parts fish meal
3 parts bonemeal
6 parts rock phosphate or colloidal phosphate
1 part kelp meal
6 parts greensand

If you want a 3-0.5.0-2.5 mix, try:

4 parts alfalfa meal
1.5 parts phosphate
0.5 part lime

A (stinky) fertilizer for your leafy greens, brussel sprouts, beets, and broccoli:
Add 1 part fish to 2 parts water in an airtight container. Place in a remote sunny spot. Stir every two days and apply in two weeks. Fish parts may include: guts, bones, heads, leftovers, sardines. A great source of nitrogen, potassium, phosphorus, and amino acids.

For a nitrogen-rich, potassium-rich recipe that includes calcium carbonate, mix dirty, untreated fish water tank with fireplace ash. Three notes of caution: Be sure to remove your fish first! Do not use saltwater. Avoid using around acid-loving plants or in alkaline soil.

Lastly, here’s an organic fertilizer recipe that will cover 100 square feet:

8 cups alfalfa meal
6 cups blood meal
6 cups bone meal
4 cups greensand
1.5 cups kelp meal
8 cups soybean meal

Regular recipes
We suggest only veteran gardeners use these recipes, as not only can some ingredients be a challenge to purchase, but mixing the wrong chemicals can be quite dangerous.

Acidic mix:
1 ounce iron (III) nitrate nonahydrate
½ tablespoon copper (II) nitrate x2.5 H2O
½ tablespoon ounce manganese (II) sulfate monohydrate
½ teaspoon ounce zinc sulfate heptahydrate
pinch of chromium (III) nitrate
pinch of cobalt(II) nitrate hexahydrate
½ teaspoon nitric acid 70%

Dilute in water to make 1 quart

Alkaline mix:
3 tablespoons sodium silicate, 42 degrees syrup
1 tablespoon sodium tetraborate decahydrate
pinch of sodium molybdate dihydrate
⅓ tablespoon EDTA free acid,
1 tablespoon sodium hydroxide

Two-part Veggie mix:
Mix 1: Calcium, Nitrogen, Phosphorous, some Potassium
7.5 ounces calcium nitrate tetrahydrate (completely predissolved)
2 ounces potassium dihydrogen phosphate (completely predissolved)
Dilute in water to make 1 quart

Mix 2: Potassium, Magnesium, Sulfur
3 ounces potassium sulfate
6.5 ounces epsom salt
¾ ounce morpholinoethanesulfonic acid

Other Pages With DIY Fertilizer Instructions:

An excellent site for understanding the best uses for liquid fertilizer and methods to make them at home. Liquid fertilizers are especially useful in soil-less growing environments such as peat-based or container-based plants.

Liquid fertilizer is also beneficial when attempting to grow cold-intolerant crops in not-so-perfect temperatures. A temporary Nitrogen deficiency occurs until soil temperatures reach about 50 degrees Fahrenheit and may inhibit early plant growth; liquid fertilizer may help.

Written by Steve Solomon, former owner of the Territorial Seed Company, and posted on the same site as above, this article provides information on a “Complete Organic Fertilizer” which works well in most food gardens.

Not only is the recipe and ingredient description supplied, but application directions are also provided based on the type and demand of vegetables. Make sure you check out the “caution” sections to understand the implications for using this type of organic fertilizer.

And here’s another take on the “Complete Organic Fertilizer.” The recipe on this site was allegedly Steve Solomon’s original recipe, which has since changed. Gardener Travis Saling published the original recipe, which he believes is more beneficial to gardeners, especially those in the Pacific Northwest.

The major change? The original recipe used lime instead of gypsum, which Travis does not recommend due to its calcium content. Judge for yourself!

Here’s a scholarly take on synthetic fertilizer types and parts for the DIYer. Professors at Virginia Tech explain the main components of fertilizer, nutrient requirements of your plants, quantity of fertilizer to apply, and application method and timing. This article is comprehensive, yet simple enough for even beginner gardeners to follow.

A wonderful collection of fertilizer recipes maintained by Gil Carandang, President of the Independent Inspectors Association of the Philippines. A few of our favorites include the Grow Fertilizer (a plant growth formula rich in nutrients, enzymes, and hormones); the Ginger-Garlic Extract (boosts plant immune system and helps fight insects and fungal infections); and the Homemade Fish Fertilizer (which promotes plant growth through Nitrogen and supplies nutrients to soil microbes).

Designed with beginner gardeners in mind. Amy Whitney from Atlanta Veggies provides a great introduction to fertilizers, including what the ratio numbers stand for, and how to create a fertilizer for your vegetable garden. This short tutorial video focuses on a 10-10-10 mix (you will learn what that means).

Who doesn’t love “totally awesome” urine? Phil Nauta from Smiling Gardener poses this uncomfortable question, but insists healthy urine is a garden’s best friend. Explore this 11-1.0-2.5 homemade fertilizer—as well as an herbal tea fertilizer—through his interesting and humorous video. So, go “start peeing in your garden!”

A catchy jingle gets you in the mood to learn about about organic fertilizer ingredients. This is a ten-minute in-depth video that not only lists organic fertilizer ingredients, but also explains them: composition, feel, and nutritional properties. Trust the Invisible Gardener from Malibu, California (don’t panic: it’s organic!).

Creative Commons Flickr photo courtesy of SusanA Secretariat