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All You Need to Know About Organic Fertilizers
When things are labeled “organic,” there’s two common responses: you might immediately think it’s better than inorganic options, or you might wonder if it’s worth the extra cost. When it comes to fertilizers, there are hundreds to choose from, both organic and inorganic options, making it seemingly difficult to choose the right kind for your plants.
The good news is, there’s no right or wrong choice, as long as you know what to look for. To help untangle the mystery surrounding organic fertilizers, we’ve compiled a guide to break down the meaning of organic, the pros and cons of organic vs. synthetic fertilizers, some specific kinds of organic fertilizers, and fertilizer recommendations for particular types of plants.
What Does Organic Mean?
First, let’s dive into the meaning. What exactly does “organic” mean? Before synthetic fertilizers became widely accessible, organic was the only option. In the early 1900’s, science allowed for some of the first synthetic fertilizers to be made, and by the 1950’s, production increased, giving consumers an option for feeding their garden for the first time. This science has continued and only expanded the options and formulations available today.
However, organic is a term that not just any company can use. There are very strict rules on obtaining and upholding organic certification. The main players in the organic certification business are the Organic Materials Review Institute (OMRI), the United States Department of Agriculture (USDA), and the National Organic Program (NOP), which is under the USDA umbrella. These departments work closely together with extension services and state offices to regulate products that are sold and marketed as “organic” to make sure they actually are.
For all the details, check out the OMRI’s website here. For those not wishing to read a very large document of regulations, we don’t blame you--here’s a summary of the most common regulations concerning anything organic:
- To label products organic, you have to have the certification to back it up.
- Natural doesn’t mean organic. Look for the official seal by the USDA or OMRI to know for sure.
- Organic products must undergo regular testing and inspections yearly to ensure no cross-contamination.
Bottom Line: If a product is labeled organic, you can trust that it is!
Is Organic Better?
There’s not necessarily a better option when it comes to organic and synthetic fertilizers. It’s a subjective matter and depends on the preferences and needs of a particular garden or gardener. Below are pros and cons of organic and synthetic fertilizers to help you better understand the two and weigh your options.
Inorganic or Synthetic Fertilizer
How to Switch to Organic Gardening
You might be wondering if it’s possible to take something inorganic and make it organic, and the answer is YES! Remember, the term organic just refers to how something is grown, not the object itself. Two identical plants can both be grown organically and inorganically without changing the plant itself.
In order to switch to organic growing, simply start using only organic products. It may take a few years for your inorganic fertilizers to work their way out of the soil, but with consistency, your plant should be organic in about three years.
Note: Just because you feed your plant organically doesn’t mean you have to do everything else organic too like organic fungicides and pesticides. Remember, it’s your garden, so have fun with it and do what you think is best, including mixing and matching your plant care if needed.
Types of Organic Fertilizers
If you’ve decided you want to try organic fertilizer, it helps to know what each ingredient is responsible for and where it comes from. The two main classifications you’ll see are plant-derived or animal-derived. These are often used together, as each carries value to plants and soil. While this isn’t comprehensive, the list below covers some of the most popular organic plant-based and animal-based fertilizer options out there.
As the name suggests, these come from plant-based materials harvested and processed into formulas for your garden.
- Both seaweed and kelp, which is a kind of seaweed, are very nutrient dense and provide high levels of Nitrogen, Phosphorous, Potassium, and micronutrients, while being water-soluble and quickly up-taken by plants.
- Seaweed and kelp are harvested and then typically formulated into a dry or liquid product that can be applied directly to plants.
- Similar to manure, the nutritional value will depend on the exact ingredients in the compost. This means compost is customizable to your plants’ needs. For example, coffee grounds will make the ph levels more acidic.
- Compost is normally tilled into the soil, added as a top dressing or made into “compost tea,” which is a liquid suspension that’s sprayed or watered onto the plants.
Animal-based products come from animals either directly, like fish emulsion or indirectly, like manure.
- Bone meal is exactly what it sounds like: sanitized and ground-up bone byproduct from meat processing plants. While it might sound harsh, it makes use of a product that would have otherwise been considered waste. It’s a yellowish powder that’s high in phosphorus, which boosts flower health. And it’s water-insoluble, making it a great option for feeding flowering plants over a period of months.
- Typically the powder is incorporated into soil mixes at the time of planting or added on top yearly to flowering plants.
- Blood meal might sound scary, but don’t worry–it’s not that bad! It’s just dried powder made up of the natural byproduct from meat processing centers. It appears dark brown in color and is packed full of Nitrogen, while being a wonderful deterrent for rabbits, deer, moles, and squirrels.
- Apply this to the soil when planting or as a top dressing for already established plants. Over a period of months, it will naturally break down in the soil, providing a boost of Nitrogen and acting as an acidifier for acid-loving plants.
- Manure can come from a variety of sources like chickens, cows, and horses, and the nutritional content will vary depending on what the animal ate and where it came from. Most, if not all manure, will need to have a processing time before it is applied to the plant to avoid any nitrogen burn.
- Manure is generally mixed into the soil or used as a top dressing. A liquid suspension called “manure tea” is sometimes used for faster absorption.
- Castings is just a nice word for earthworm poop that might be labeled on a product as “Vermicompost”. Earthworms are fantastic at decomposing matter like fallen leaves that are then processed through the worm. The result is a rich and finely milled dirt that adds needed organic matter and microorganisms to the soil.
- Worm castings are most often worked into soil mixes or added as a top dressing around already established plants.
- Fish emulsion is by far the smelliest on this list (in our opinion), but plants will love it. Fish emulsion is composed of heated and processed fish that are then cold-pressed and filtered. The result is a wonderfully smelly and nutrient-rich liquid that is water-soluble, making it easy for plants to quickly uptake its Nitrogen component.
- It’s often sold in concentrations that you dilute with water (outdoors only!) and then water your plants with.
- A natural byproduct of oysters is the shells they come in. When mixed in the soil, these provide needed aeration, make the soil more basic (just like lime does), and add calcium, phosphorous, and magnesium.
- The shells come in a cleaned and crushed up form and appear like a powder that you incorporate into the soil or sprinkle around already planted plants.
- Bonus tip: create a ring of shells around your plants to keep snails and slugs out, as they dislike crawling over them
- Feather meal is a natural byproduct of processing poultry. The feathers are sterilized with high heat and are finely milled into a powder containing around 12% Nitrogen, but are not water-soluble making it a slow-release option.
- Feather meal is most commonly used to aid in Nitrogen uptake to support lush, green foliage. It works best when mixed into the soil so that it’s near the roots of the plant.
- This is simply the waste produced by bats and seabirds that’s collected and processed. It's a solid choice to use for plants thanks to its high and well-balanced levels of Nitrogen, Phosphorus, and micronutrients.
- Guano is water-soluble, so application forms range from use in the soil, as a top dressing, or in a liquid suspension sprayed on the plant.
How to Use Organic Fertilizers
Whether you use organic or inorganic fertilizers, the timing of your application should be the same. Plants need food and the most nutritional support when they’re actively growing during spring. And fertilization should be paused once the plants stop growing and enter dormancy, around fall.
As with any product you add to your garden, make sure to read the manufacturer’s instructions, as formulations vary, even if they have the same main ingredient. You can also find balanced and pre-mixed organic fertilizers instead of the individual ingredients listed above. We highly recommend going the pre-mixed and formulated route, especially if you’re just getting started with organics or don’t need a lot of one particular ingredient.
Organic Fertilizers by Plant Type
Here’s a quick guide on specific plant types and the organic fertilizers we recommend using for each.
Need evergreen support for your hollies, gardenias, pines, and spruces? Try our espoma holly-tone or soil acidifier to help feed your plants. You can also mix feather meal into your planting area to give a boost of Nitrogen.
Need indoor or foliage support for your house plants like colocasias, monsteras, or alocasias? Use a high nitrogen fertilizer like blood meal, bone meal, or fish meal that supports foliage (remember, fish emulsion should be mixed outside due to its potent smell).
Need all-around organic fertilizer to help a large variety of plants? Worm castings, compost or manure are mild but rich with nutrients that help the microbiome of your soil take off, regardless of what’s planted. If you only need a little, try this one.
All in all, it doesn’t matter if you choose organic or inorganic fertilizers. As long as your plants get the nutrients they need, they’ll be happy. And remember, fertilizers are fertilizers, so keep them away from small hands and pets, as they can be harmful to them. Lastly, remember to supplement if you need to and never add too much at one time. Reach out to one of our Plant Specialists if you need more assistance, and enjoy watching your garden grow!