Nitrogen is absolutely vital for plants, and boosting this nutrient in your soil will help you grow healthier flowers, herbs, and vegetables. There are many organic methods you can use, which we’ll cover in this your complete beginner’s guide on how to add nitrogen to the soil.
Why Your Plants Need Nitrogen
Nitrogen (N) is essential to plant growth. Without it, they wouldn’t be able to create the protein and amino acids they need to survive. Even a plant’s DNA depends on this element, as it helps to create new cells.
Although nitrogen is in the air around us, plants access it through the soil. Thus, beginner gardeners need to learn how to convert nitrogen into the soil for the best results in plant growth. There are two main ways to do this: nitrogen fixing, or composting. Both are natural ways to add this vital nutrient without using harsh chemicals.
Nitrogen fixation is essential to allow photosynthesis to happen. There are bacteria that use the nitrogen in the air to convert it into a solid that plants can use. You can increase the number of these bacteria in your soil by planting crops like beans, peas, or other legumes (more on this later).
Create Homemade Fertilizer
In contrast, composting involves creating fertilizer at home so you can add vital nutrients to the soil each year. However, fertilizer will only feed your actively growing plants, while compost adds nutrients directly to the soil. The latter is the best way to grow the healthiest plants over long periods of time.
Instead of buying a large bag of potting mix from your local garden center, add your own compost to the soil. This will promote plant growth, as well as allowing you to recycle biodegradable waste such as leaves or vegetable scraps.
A nitrogen-rich compost as bacteria and other symbiotic life forms that allow veggies to feed themselves, fight off diseases, and boost flavor. In addition, compost allows soil to retain moisture levels. You can purchase bagged compost, but a homemade version is the best source of nitrogen.
If you’ve never made your own compost before, you can learn how to make a pile at home. Alternatively, you can purchase it from a garden supply store. Many gardeners choose to make their own for small projects, and buy commercial compost as needed for large-scale grows.
How to Tell if Your Soil Needs Nitrogen
A plant with a nitrogen deficiency will grow stunted and smaller than normal. Because they can’t make their own cells without nitrogen, plants won’t grow to their full potential without it.
Leaves or foliage turning yellow is the first sign of a nitrogen deficiency in most plants. You may also notice less flowering or fruits, and your plants may appear thin or pale.
How to Test Nitrogen Levels
The only way to test the nitrogen levels in your garden is with a soil-testing kit. You can pick one up from your local plant nursery or hardware store, or you may find a service test the soil for a small fee.
The kits you can buy yourself are quick and easy to use, but they only focus on nitrogen. A professional horticulturist can let you know what other deficiencies your soil suffer from.
How to Add Nitrogen to Soil to Fix Deficiencies
You could purchase a chemical fertilizer to boost nitrogen levels, or you can take advantage of the many organic amendments. Organic methods on how to add nitrogen to soil take more time, but they will typically maintain an even level over a longer period of time.
You can add banana peels to the bottom of your compost pile, or you can add them directly into a flower bed before you plant. After you dig each hole, place the peels in and allow them to degrade for a few days before you plant your flowers.
If you enjoy a morning espresso, save the grounds to reuse them in your garden. Even if you don’t enjoy drinking coffee yourself, you can collect coffee grounds from a nearby coffee shop. You can even ask a neighbor for theirs.
Coffee releases nitrogen into your soil, as well as magnesium, potassium, copper, and phosphorus. It also helps keep pests like slugs and cats away, while attracting beneficial earthworms. There a few ways you can use coffee grounds to add nitrogen to your soil:
For a quick boost, sprinkle your used grounds directly onto the soil in your potted plants or raised garden beds. Water the grounds into the soil or add them to outdoor plants just before it rains.
Or, you can add the grounds to your compost pile to boost nitrogen levels. The grounds quickly break down when mixed into compost, and unwashed grounds will often lower the pH balance of your soil. This helps acid-loving plants like tomatoes and berries thrive.
Lastly, make a diluted, weak coffee infusion using your old grounds and water the plants directly with the liquid. Wash the coffee grounds for a more neutral pH balance, or use them as is for more acidic soil.
Fish Tank Water
Fish manure, which is high in nitrogen, potassium, and phosphorus, is a great natural fertilizer. After cleaning your fish tank, save the old water in a bucket and use it to feed nutrients to your plants. However, don’t ever use the method in conjunction with fish antibiotics, or any other medicine for sick fish. You’ll kill your plants.
Allow old eggshells to dry, crush them, and add them to soil or your compost pile for a slight nitrogen boost. The amount of nitrogen this method produces is low, but adds a decent amount of calcium to your soil.
You have to clean out the fireplace anyway, so use the wood ash to add nitrogen to your soil. Don’t scatter the ashes on a windy day, however, or you’ll end up eating them. Additionally, don’t layer the ash more than 1/8 inch thick, as any more will create a paste when it gets wet.
Weeds and Legumes
Plants in the legume family naturally convert airborne nitrogen into a compound that plants can use. As a result, planting crops like beans and peas as companion plants will help heavy feeders like asparagus or corn. Weeds like nettles or burdock also work well as natural plant fertilizers.
Adding grass clippings from your yard to your compost pile is a free, easy way to add nitrogen and potassium. You can use a mulching mower to collect the clippings easily, or rake after you mow the yard and shovel them directly into your garden. Add the clippings around the base of your plants in multiple thin layers.
If you have herbivorous animals at home, you can use their manure to create a rich nitrogen additive for your soil. Fresh manure contains too much nitrogen, however, whereas 6-month-old manure is more easily absorbed. The best animals for this process include:
Manure also adds nutrients like phosphorus and zinc, and you can purchase it from a garden center as well. Protect yourself from illness by always wearing gloves when handling animal waste. Also, make sure to wash your hands well when you’re done.
It may sound gross, but human urine works extremely well as a plant fertilizer. It’s sterile, and as long as it comes from a healthy person, can be added to a compost pile to add more nitrogen than a store-bought fertilizer. However, the urine must be diluted or it will burn the plants. Try one cup of urine to eight cups of water for the best results.
Plant-based food scraps that normally wind up in the trash can instead be added to your compost pile to enrich the soil with nitrogen. The process takes several months to complete, so begin during the early summer to have compost ready for next spring. The best food waste to add to your compost include:
- Tea leaves
- Stale bread
- Corn cobs
- Fruit rinds
- Veggie scraps
Follow our guide on what NOT to add to compost to learn what does and doesn’t go into a healthy compost pile.
Create a leafy mulch before winter strikes by scattering 2-4 inches of leaves over your garden. After all the plants have been removed from your garden patch, add the leaves, and water them to keep them in place. They’ll break down during the winter, feeding your soil with nitrogen so it’s ready for summer planting.
You can also add leaves to your compost pile for the same results. Just make sure they’re dry before adding them to the compost to avoid unpleasant decomposition odors.
Chemical fertilizer from your local garden is a quick way to boost nitrogen. It’s an easy treatment for nitrogen deficiency, but the benefits will fade much quicker than the aforementioned organic methods. To find the right fertilizer for your needs, look for a 10-10-10 N-P-K (Nitrogen, Phosphorous, Potassum) ratio.
Finally, additives like bone meal, blood meal, kelp, or fish emulsion can be helpful. They work as great chemical-free ways to add nitrogen-rich fertilizer to your plants.
However, the best organic method depends on the type of foods you normally purchase. If you eat a lot of eggs, bananas, and veggies, you should be able to create enough nitrogen from their scraps alone.
The result is less trash for you to throw out, and a healthier garden overall.