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Best organic fertilizer

Which organic fertilizer is best?

Whether you covet a lush, green lawn or you’re cultivating vegetables, your soil may benefit from an application of fertilizer. Fertilizers help plants grow better by supporting helpful organisms living in the soil, and organic fertilizers accomplish this without the use of ingredients like chemical salts that can do more harm than good.

If you’re looking for an easy-to-use organic fertilizer to help flowers bloom, Fox Farm Organic Big Bloom Liquid Concentrate Fertilizer may be the top choice for your plants.

What to know before you buy an organic fertilizer

Organic vs. synthetic fertilizer ingredients

Organic fertilizers are derived from plant and animal sources like organic waste, seaweed or microbes, whereas chemical or synthetic fertilizers are manufactured from minerals, gasses and inorganic waste. Popular types of organic fertilizer include fish emulsion, bone meal, peat and manure. Different plants have different preferences for the nutrients provided by these ingredients.

It's important to note that the term “organic” is not yet regulated for fertilizers, so the type and quality of organic fertilizer ingredients can vary. Look for fertilizers marked organic by the Organic Material Review Institute, a third-party nonprofit that verifies product adherence to USDA organic farming standards.  

Organic fertilizer forms

Like synthetic fertilizers, organic fertilizer comes in liquid and dry granule formats. Liquid fertilizers deliver nutrients faster, while granules dissolve in the soil more slowly over the course of a growing season. It’s okay to use both, but be careful not to overdo it, since over-applying fertilizer can damage plants.

Be patient

Chemical fertilizers may deliver more immediate results, but they don’t typically offer the same lasting benefits to your plants as organic fertilizers. Organic fertilizers contain lower quantities of macronutrients, so they won’t provide a quick fix, but they can improve your soil quality over time without adding harmful chemicals to the environment.

What to look for in a quality organic fertilizer


In general, organic fertilizers last longer than synthetic fertilizers because they aren’t as water-soluble, so they stay in the soil longer instead of being quickly absorbed into plant roots. Read the instructions and evaluate the fertilizer form to make sure it’s suitable for your needs.

NPK analysis

All fertilizers are required to provide their NPK concentration. This system tells the user how much nitrogen (N), phosphorus (P) and potassium (K) the fertilizer contains. These are the three primary macronutrients that keep plants healthy, and you may need fertilizers with different NPK ratios for different parts of your garden. 

However, this ultimately depends on what nutrients are lacking in your soil. For example, if your soil already contains lots of phosphorus, you don’t want to buy a fertilizer that will add more phosphorus. Save yourself time, money and frustration by testing your soil before you start adding fertilizer. A soil test can tell you which nutrients your plants actually need so you can shop for fertilizer accordingly.


Gardeners need to be careful when applying chemical fertilizers because adding too much can risk root burn. While it’s much harder to burn your plants with organic fertilizer because their concentrations tend to be lower, it’s still important to follow the package instructions to avoid issues like insect infestations. 

How much you can expect to spend on an organic fertilizer

Organic fertilizers tend to cost $0.11-$0.27 per square foot. Depending on the ingredients and formula strength, a typical 4- to 5-pound bag of fertilizer costs $7-$17, while a half-gallon of liquid fertilizer costs around $20.

Organic fertilizer FAQ

Can I use compost instead of fertilizer?

A. Not exactly. In fact, you may want to use both. Compost is a natural material like organic fertilizer, but it doesn’t have the same concentrations of NPK as fertilizers. Compost helps maintain overall soil health and contributes beneficial microbes, while fertilizer is formulated to deliver essential macro- and micronutrients. Adding compost to your soil regularly can help it become richer and reduce its need for fertilizers overall.

How do I know if I'm using too much fertilizer?

A. Some of the signs your plants are getting too much fertilizer include:

  • Leaf scorch or dried leaves
  • Blackened, limp roots 
  • Yellowing or browning leaves
  • Dropping leaves
  • Stunted or leggy growth

What’s the best organic fertilizer to buy?

Top organic fertilizer

Fox Farm Organic Big Bloom Liquid Concentrate Fertilizer

What you need to know: If you’re struggling to get your flowering plants to bloom, this liquid fertilizer is a good pick.

What you’ll love: It has practically no odor, especially compared to other organic fertilizers. This combined with its liquid formula makes it one of the more pet-safe organic fertilizers on the market. Along with flowering plants, many users report good results with their indoor plants.

What you should consider: It’s pricey, and how long the bottle lasts depends on how many plants you need to treat. It’s best for flowering ornamental plants and may not produce results in plants like vegetables.

Where to buy: Sold by Amazon

Top organic fertilizer for the money

Jobe’s Organics All-Purpose Granular Fertilizer

What you need to know: With its 4-4-4 ratio, this all-purpose organic fertilizer is a great choice if you only want to buy one kind of fertilizer.

What you’ll love: The easy-to-use granular formula includes bone meal, poultry manure and beneficial bacteria and fungi to help improve soil quality. It produces results in everything from vegetables to trees and flowering perennials. The 36-pound bag will last a long time.

What you should consider: It’s probably too stinky for indoor plants; even for outdoor use, the smell is intense.

Where to buy: Sold by Amazon

Worth checking out

Neptune’s Harvest Organic Hydrolyzed Fish and Seaweed Fertilizer

What you need to know: This 2-3-1 NPK fertilizer is a good all-purpose liquid fertilizer that uses fish byproduct from North Atlantic fisheries.

What you’ll love: It’s easy to follow the instructions to use this fertilizer on everything from fruits and vegetables to lawns and even indoor plants. The diluted formula can be poured onto soil or sprayed on leaves.

What you should consider: Like other liquid concentrates, it needs to be measured and mixed with water instead of being applied directly to the soil. It has a strong fishy smell at first, but it dissipates quickly.

Where to buy: Sold by Amazon

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Laura Duerr writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.

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