Every garden has a story to tell, and the soil in your garden is an essential part of that story. Fertilizer provides the food plants need to thrive, giving them nutrients like iron that can be hard for them to take up on their own.

Organic fertilizers work slowly and are broken down by soil organisms to make the nutrients available to plants. They also contain micronutrients that are important for plant health.

Organic Fertilizers

As any gardener knows, organic fertilizers contribute to a healthy garden with vibrant blooms and bountiful produce. They help support the microbes, fungi and organisms that decompose organic matter in the soil and offer your plants essential elements in perpetuity.

Organic fertilizers are readily available at homesteads and farmers’ markets. They typically contain organic matter such as bat and bird guano, composted chicken manure, blood meal, fish emulsion and urea for nitrogen; bone meal, kelp and greensand for phosphorus and potassium respectively.

Synthetic Fertilizers

A fertilizer marked 10-10-10 means equal parts nitrogen, phosphorus and potassium. However, the majority of any bag of synthetic fertilizer is comprised of salts and other toxic residues. These contaminants end up in the air we breathe, the dirt kids and pets play in, water runoff and eventually, in our food and plants.

Synthetic fertilizers are like speedy gonzales, they give a quick boost of nutrients to your plant—but it’s possible to go overboard. And they don’t add any organic content to the soil or support any microbes, so they aren’t as good for your garden long-term.

Granular Fertilizers

For seeds and new plantings, granular fertilizers can be worked into the soil before planting or sprinkled at the drip line of established plants. They can also be applied during a rainy day to assist the process of pushing nutrients down to plant roots.

Nitrogen (N), phosphorous (P), and potassium (K) are essential for most plants to grow well and produce large yields. Thoughtful use of natural fertilizers contributes to a healthy garden without killing beneficial soil microorganisms and polluting waterways.

Liquid Fertilizers

Liquid fertilizers are easy to apply and can be sprayed directly on leaves or soil. They are usually made with a balanced mix of nitrogen, phosphorus, and potassium. They may contain organic ingredients such as fish emulsion. They may be a good choice for vegetables, which prefer a high nitrogen content, or herbs that need phosphorus.

They are often diluted before use, and should be applied as instructed on the label. These are fast-release fertilizers and degrade quickly under soil microbes and temperature.

Slow Release Fertilizers

Slow release granular fertilizers provide steady nutrition to plants over a period of time. They are usually a combination of organic and synthetic materials with different nutrient profiles. It’s important to get a soil test first, before choosing a fertilizer. Different plants have different nutrient needs. Peppers, eggplants, and tomatoes need a higher phosphorous content than nitrogen to promote fruiting and flowering.

Bone meal, a byproduct of animal slaughter, is rich in phosphorus and calcium and helps boost root growth and flowers. Cottonseed meal, a dry byproduct of the cotton industry, improves soil texture and increases nutrient availability.

Specific Plant Fertilizers

Plants require the right balance of sunlight, water and nutrients to thrive and contribute to a healthy landscape. Most garden plants need regular feeding with fertilizer to produce beautiful flowers and fruit, establish a strong root system and fight diseases and insects.

Natural or organic fertilizers are derived from plant, animal and mineral sources such as alfalfa meal, kelp, blood and bone meal and soft rock phosphate. These products are converted to smaller nutrient molecules by microorganisms in the soil, making them available for uptake by plant roots.


Compost is a great soil conditioner and slow-release plant fertilizer. It is a rich source of nitrogen, phosphorus and potassium. It also adds micro-nutrients and improves soil texture. As compost decomposes, a host of tiny bacteria and fungi break down organic molecules and stockpile the nutrients for uptake by plants.

Homemade compost can be worked into the soil at planting time or used to make a nutrient-rich “compost tea” for established plants. It can rob the soil of its nitrogen, so it is best used in conjunction with other organic nutrient sources.


Manure contributes nitrogen, phosphorus and potassium to the soil while improving its structure. It also increases microorganism and worm activity, which help break down soil nutrients for easier absorption by plants.

If using manure, look for organic sources or call local farms that raise chickens or rabbits to see if they have any to spare. Avoid herbicide-laced manure that could be toxic to garden plants. Also, be sure that manure is well aged before using it.

Bone Meal

Bone meal is an organic, slow-release fertilizer that consists of ground animal bones, usually beef. It contains phosphorus and calcium and contributes to a healthy garden. It is also good for balancing other high nitrogen, organic soil amendments like rotted manure.

It is important to check the pH level of your soil before using this fertilizer because it adds significant amounts of phosphorus. If the soil is alkaline, you can use peat moss or elemental sulfur or iron sulfate to bring it down.