Homemade Nitrogen Fertilizer

This guide explains how to correct nitrogen deficiency in soil using natural nitrogen sources for plants. Nitrogen is the mineral a plant needs in the most significant amounts, and a healthy plant will contain three to four percent nitrogen in non-root tissues.

Scroll to the bottom for two simple homemade organic nitrogen fertilizer recipes - one with grass clippings and urine and the other with leftover coffee grounds.

Why organic nitrogen fertilizer is important

Long before the scientific discovery of the element nitrogen and its role in plant nutrition, farmers noticed that planting legume crops like clover made soil fertile. Uniquely among plants, legumes produce their own nitrogen and replenish the soil's nitrogen content. This is thanks to a bacteria (Rhizobiaceae, α-Proteobacteria) in legume roots.

Although nitrogen gas makes up 80 percent of the earth's atmosphere, man-made nitrogen was rare before the beginning of the 19th century. This was until the invention of the Haber-Bosch process in the early 20th century - a method to obtain nitrogen from the air. 

Cheap synthetic nitrogen fueled the 20th-century revolution in global food production, creating a massive ecological crisis. Synthetic nitrogen run-off from agricultural land into the wider environment constitutes a significant pollution problem.

Homemade, organic fertilizer recipes tend to contain less concentrated amounts of the target nutrients than commercial, chemically synthesized ones. The lower potent concentration reduces the chance of damaging plants by over-fertilizing. They are also more environmentally sound because they have less chance of releasing excess fertilizer into the wild.

Instead of synthetic nitrogen fertilizer, opt for organic alternatives. You can also make your organic version at home. Opting nitrogen from organic sources means you won't introduce surplus nitrogen into the ecosystem, and you'll be protecting and nurturing your plants at the same time. 

What is in commercial plant fertilizers?

All plant fertilizers contain nitrogen, phosphorus, and potassium. These are the macronutrients, the elements found in the most abundant quantities in plants. Different types of fertilizer contain these macronutrients in different amounts and ratios. 

• Nitrogen (N) is crucial for vibrant foliage and stems, contributing to chlorophyll synthesis for optimal plant coloration and photosynthesis. Home gardeners frequently utilize nitrogen-rich fertilizers for their houseplants.
• Phosphorus (P) is essential for strong plant structure, promoting the growth of flowers, fruits, and root systems. When plants exhibit overall poor development or display dark or purpled leaves, phosphorus supplementation may be necessary.
• Potassium (K) maintains root health and supports flower and fruit development. It enhances plants' resilience to stress, including drought. Plants with abundant blooms, like orchids, benefit from potassium before and throughout their flowering stage.

While plants also require thirteen other elements in smaller quantities to carry out essential physiological maintenance and achieve growth, these micronutrients are usually found in sufficient quantities within the soil. Plants need all three macronutrients and thirteen micronutrients.

What are nitrogen-rich fertilizers?

Nitrogen-rich fertilizers contain a higher nitrogen ratio than the two other macronutrients (phosphorus and potassium). You can identify commercial brands of nitrogen-rich fertilizers by looking for nutrient ratios like 10-5-5, which means that the macronutrient content is two parts nitrogen to one part phosphorus and one part potassium. 

Learn more about fertilizer NPK and NPK ratios in this guide.

When to use nitrogen fertilizer

Because nitrogen builds amino acids, they are important in developing cell membranes and chlorophyll, essential for photosynthesis. Houseplant collectors will find that nitrogen fertilizers are their plants' best friend for big, healthy leaves.

Like all fertilizers, nitrogen-rich fertilizers should only be used in the immediate lead-up to and during a plant's growth season. But when it comes to houseplants, this rule can be stretched when using a very gentle, natural nitrogen-dominant fertilizer on plants that get optimal light, warmth, and water. That's because the indoor conditions mimic a year-round growing season of tropical plants.

In vegetable gardens, nitrogen benefits leafy vegetables like kale, lettuce, and spinach in their growth season. Beets, brussels sprouts, broccoli, cabbage, and cauliflower also need high nitrogen levels. Underground veggies and legumes (such as carrots, fava beans, peas, radishes, parsnips, and turnips) do not need nitrogen supplementation. 

Signs of nitrogen deficiency in plants

Nitrogen deficiency restricts plant organ growth, affecting roots, stems, leaves, flowers, fruits, and seeds.

Chlorophyll gives plants their green color, so nitrogen deficiency turns leaves pale. If the plant is deprived of nitrogen as it grows, the lower leaves on the stem will become pale. This is because nitrogen reserves from the base of the plant will be transported to younger leaves at the very top if their nitrogen levels are low. 

Homemade nitrogen fertilizer recipe #1: Urea and grass

Both of these recipes will produce fertilizers high in nitrogen with little of the two other macronutrients - phosphorus and potassium. Use only when the soil is deficient in nitrogen.

This is the easiest fertilizer to make at home - both ingredients are readily available: grass and urine! Urine is an overlooked nutrient source that is too often wasted. Grass clippings are a good source of nitrogen, with an NPK ratio of 4:2:1 (4 % nitrogen, 2 % potassium, 1 % phosphorus). 

What you need:

• One 5-gallon bucket
• Grass clippings to loosely fill bucket
• 1/4 cup Epsom Salt
• 2 cups urine
• water

How to make homemade nitrogen fertilizer recipe #1:

1. Fill a 5-gallon bucket with grass clippings
2. Cover grass clippings with water and leave for three days
3. Mix 1/4 cup of Epsom salt with two cups of urine
4. Add the Epsom salt/urine mixture to the steeped grass clippings
5. Strain the liquid and dilute it by half with water
6. Pour into a bottle, and it's ready to apply to the soil

Recipe for homemade nitrogen fertilizer #2: Coffee grounds

If using urine for your homemade nitrogen fertilizer feels out of your comfort zone, this recipe may be less intimidating and better smelling, and it still uses natural waste - coffee grounds.

For plants that like a lower acid content, use decaffeinated coffee grounds.

What you need:

• 2 cups coffee grounds
• 5 gallons water
• Spray bottle

How to make homemade nitrogen fertilizer recipe #2:

1. Add two cups of used coffee grounds to 5 gallons of water
2. Leave overnight
3. Strain the liquid into a bottle, and add to the soil or spray directly onto your plant's leaves

If you would like to experiment with your own organic fertilizer recipes, here's a helpful guide for NPK ratios in many organic materials. You can use it to figure out which ingredients you need to create a perfect NPK ratio mixture for your plant.   

P.S. Live in an apartment and want to grow veggies? Check out this article.