When you first start gardening there are a few basic elements that most people are already aware of – their plant is going to need soil, water, and sunlight. Sunlight just requires the proper placement of your plant. And watering is pretty self-explanatory, though you may need to fine-tune your quantity and frequency. But soil.. isn’t that sort of a one-time thing? You fill a container or raised bed with some nice soil and call it a day?
Well… sadly, no.
That’s where fertilizer comes into play. Learn why fertilizer is important, the difference between organic and synthetic fertilizers, and 12 organic fertilizers for your garden.
Why You Should Use Fertilizers
While your soil isn’t something you’ll have to concern yourself with every day, it does get depleted over time. Plants need nutrients in order to grow and thrive. Over time, the nutrients in your soil get depleted by what you’re growing. And fertilizer helps to add those nutrients back into your soil so that you continue to grow healthy plants. Fertilizers are basically plant food.
The main three nutrients (known as macronutrients) that plants need are nitrogen (N), phosphorous (P), and potassium (K). Fertilizers add these nutrients back into the soil and are typically listed on the fertilizer package as N-P-K. For example, a fertilizer that lists 10-5-5 would mean that the fertilizer contains 10% nitrogen, 5% phosphorous, and 5% potassium.
Fertilizers also add secondary nutrients (calcium, magnesium, and sulfur), and also micronutrients, such as iron, manganese, zinc, copper boron, and molybdenum. These additional nutrients are actually equally as important, they just aren’t needed in the same quantity as the NPK trio.
Organic vs Non-Organic Fertilizers
There are two types of fertilizers – organic and non-organic (also known as chemical or synthetic). Organic, in this context, includes fertilizers approved for organic gardening, which are both organic (like compost) and inorganic (like rock dust). These fertilizers are considered safe to use for organic gardening. Not all natural materials are considered safe for organic gardening, so those are excluded.
As organic produce becomes more popular, and more awareness is created around organic food, more people are becoming interested in organic gardening. One of the main aspects of organic gardening is not using anything synthetic or otherwise harmful in your garden. The fertilizer you use can play an important role when your desire is to have an organic garden.
Advantages of using organic fertilizers:
- Slow-released, so it’s more difficult to over-fertilizer (and burn) your plants.
- Little to no risk of toxic buildup in your soil where you’re growing food.
- Renewable, biodegradable, sustainable, and environmentally friendly.
- Improves soil texture and structure over time, along with the microbial ecosystem.
- Includes secondary and micronutrients that synthetic fertilizers sometimes leave out.
There are 2 downsides to organic fertilizers. 1) Some can be more expensive and 2) they are slow-released. The fact that they are slow-release is also a benefit, but they require time to breakdown. While some can be expensive, others are fairly cheap and can even be created/grown at home.
Synthetic fertilizers, on the other hand, can be made from nonrenewable sources such as fossil fuel. They help plants to grow but do not create an environment to sustain your soil. Synthetic fertilizers don’t include decaying matter, which helps improve your soil structure. Synthetic fertilizers are also created with high concentrations which can harm your plants if you use too much. Repeated applications can also cause toxic buildup and disrupt the microbial ecosystem in your soil. They can also release greenhouse gases. For me, the cheaper costs and instant absorption of synthetic fertilizers aren’t worth the long-term harm that they can cause. They can cause harm to your food, your children, your pets and wildlife, and the rest of the planet.
12 Organic Fertilizers
This list below shows different organic fertilizer types that are more natural to use in your garden. There are multiple companies that sell each of these types of fertilizers, and some you can even make at home.
Compost is broken down organic material that can be added back into the soil to help your plants grow. You can even make your own Compost while minimizing your waste. You can compost fruit and vegetable scraps, coffee grounds, crushed eggshells, and more. If you don’t want to have your own composter, you can also purchase bags of compost from a local nursery or places like Lowes and Home Depot. Compost requires a moderate amount of time to break down and add nutrients to your soil.
2. Cow Manure
The cow manure you’ll want to use is actually composted manure. It’s aged and mixed with compost, and over time as it breaks down it adds nutrients to your soil. Composted cow manure adds both macro and micronutrients to your soil, helps microbial life, and improves your soil structure and texture. It helps your soil hold water while also holding air. My favorite to use is Black Kow that, currently, you can purchase from Lowes for about $5. Cow manure is moderate when it comes to the amount of time required to break down and add nutrients to your soil.
3. Worm Castings
Also called vermicompost, worm castings are like compost on steroids. It’s a plant superfood. The earthworms breakdown of organic matter so that it includes a higher saturation of nutrients compared to regular compost. This means a little goes a long way. Worm castings include macronutrients and well as micronutrients. They also have a neutral pH of 7.
4. Blood Meal
Blood meal is an excellent source of nitrogen. It also provides nutrients to your plants fairly quickly. My go-to is by Miracle-Gro, but there are other options available. It comes in a granular form and helps your plants stay green and lush. It also raises the acid level of your soil, which lowers the pH level of your soil. This is one of the organic fertilizers where you can overdo it and burn your plants, so it’s important to follow the directions.
5. Bone Meal
Bone Meal is a great source for phosphorus and calcium. My go-to for this one is also by Miracle-Gro. And again, there are other companies you can purchase this from. I’m not sure how long this will be available on Amazon – but there’s a blood meal + bone meal option that saves you about $8 versus buying each product separately. Bone meal can help prevent blossom end rot and also help if you find your flowers falling before they set fruit. Bone meal takes longer than blood meal to break down and add nutrients to your soil.
6. Comfrey Tea
Comfrey is high in nitrogen, phosphorous, potassium, and calcium. If you grow comfrey you can take cuttings and soak them in water for a few weeks. You can then dilute this and add a little to your plants. A little goes a long way, and it does have a tendency to smell while you’re leaving it to soak in water. However, I’ve heard great things about comfrey tea and other compost teas which allow nutrients to be absorbed much quicker. Comfrey clippings can also be composted, or just tilled into your soil.
7. Fish Emulsion
Fish emulsion is a good source of all three macronutrients, with a higher concentration in nitrogen. It provides nutrients immediately to your plants, unlike some fertilizers that take their time to break down. I’ve used this before, and will say, it’s the smelliest out of all the organic fertilizer options. Imagine cooking fish and then leaving it outside on a warm summer’s day. 🙂 I’ve read that hydrolized liquid fish includes the same benefits without the small, so that’s something to keep in mind if you’re interested. It also includes more trace nutrients.
8. Bat Guano
Bat guano is a source for all three macronutrients. It’s moderate to immediate when it comes to how soon it provides nutrients to your plants. Bat guano also helps to adjust your soil pH and improves soil texture.
9. Alfalfa Meal
Alfalfa meal helps to add all three macronutrients, along with many trace nutrients. It does take a few months to be broken down and absorbed by the plants. Alfalfa meal is fermented alfalfa plant seeds. You can typically find alfalfa meal at feed and animal stores. It can also be used to accelerate compost piles.
10. Rock Phosphate and Azomite Rock Dust
OK, ya got me, these are technically 2 different organic fertilizers. But it’s worth pointing out the differences so that you don’t confuse the two. I originally thought they were the same – ground-up rock. There are multiple rock powders available and they all help to add nutrients to your soil. Rock phosphate is a good source of phosphorous and calcium. Azomite rock dust is naturally mined volcanic rock dust comprised of over 70 minerals and trace elements.
11. Liquid Seaweed
Also referred to as liquid kelp or kelp extract, liquid seaweed is what it sounds like. Liquid… seaweed. 😀 This contains nitrogen, phosphorous, and potassium in small amounts, but it is best known for adding micronutrients. Unlike some organic fertilizers that take a while to break down, liquid seaweed adds nutrients that are immediately available for plant use.
12. Green Manure
Green manure is slightly different than the other organic fertilizers listed above, but still worth mentioning. The time to use green manure is during fallow seasons – aka seasons where you’re not growing anything else. Green manure is actually the act of growing a specific type of plant that will then be tilled back into the soil, which adds nutrients. Green manures are often cover crops (crops grown to protect and enrich the soil). Some examples of green manure include clover, alfalfa, and cow peas.
What’s your favorite organic fertilizer to use? Comment below!