8 Best Fertilizer for Onions 2022 [Reviews & Guide]

Onions are the edible bulb that is packed with vitamins, minerals, and antioxidants. The good news; everyone can grow onions to meet their family needs.Because they are easy to grow and don’t need any specialized environment.

But you must provide fertilizer to get the bigger onions bulb and green. There are hundreds of fertilizers available in the market today. Sad but true, all are not good for onions.

Now the question; what is the best fertilizer for onions?

In a nutshell, the organic or chemical(non-toxic) type of fertilizer that has a well balanced NPK ratio and other nutrients. You can also apply organic bone meal or bulb type fertilizer to onions.

For your convenience, In this article, I listed and reviewed the best fertilizer for onions that you can apply to produce better and bigger onions.

In a Hurry? Here is the overall best fertilizer that you may buy right now for any varieties of onions including red onion, yellow onion(walla walla onion), green onion, white onion, spring onion, sweet onion, and pearl onion.

Best Fertilizer for Onions-Comparisons

Jobe's Organics Bone Meal Fertilizer2-14-0OrganicGranular
Espoma Bulb-Tone3-5-3OrganicGranular
Burpee Bone Meal Fertilizer6-8-0OrganicGranular
Lilly Miller Fish Emul Fertilizer5-1-1OrganicLiquid
Homesteader Hobbies Onion Fertilizer3-4-3OrganicGranular
Fox Farm Grow Big Liquid Fertilizer6-4-4OrganicLiquid
Dr. Earth All Purpose Fertilizer4-4-4OrganicGranular
Miracle-Gro All Purpose Fertilizer

You Should Know

Onions require higher nitrogen. Yes! It is true but not only nitrogen. That’s why you need fertilizer that contains other nutrients too. But in my list, most of the fertilizer has lower nitrogen.

Want to know why? Let me explain-

Most of the fertilizer has a small portion of slow-release nitrogen. But the other nutrients are not coated as slow release. As a result, they can leach out easily with surface water but nitrogen remains in the soil for further uptake.

Thereafter, if you add nitrogen to your onion, you can apply 1 tablespoon of ammonium sulfate(our pick: Ammonium Sulfate by Earthborn Element) additionally with the other NPK fertilizer. Ammonium sulfate is the best nitrogen fertilizer for onions.

Remember; Adding too much ammonium sulfate can decrease the soil pH and you know 5.5-6.5 is the perfect range of soil ph for onions.

Best Fertilizer for Onions-Reviews

1.Jobe’s Organics Bone Meal Fertilizer

Jobe's Organics Bone Meal FertilizerAre you looking for the best organic fertilizer for onions? Here is the bone meal fertilizer for onions from Jobe’s Organics. It is an OMRI certified organic fertilizer for onions.

According to the NPK ratio, this fertilizer has 2% nitrogen,14% phosphate ,and 0% potash.Also, this fertilizer contains 15% calcium. All are the most required nutrients for onion sets.

The plant can uptake nutrients instantly and meet the nutritional demand of the most hungry onion plants.

All the nutrients are derived from some organic sources. So, you don’t need to worry about pets and your health.

Besides onion, you can also apply this fertilizer to other bulbs and rhizomes like garlic, ginger, and turmeric

To apply this best fertilizer for garlic and onions

Sprinkle 1 teaspoon around the per plant, mix into the soil, apply water and get bigger onions with healthy plants.


2.Espoma Bulb-tone  Plant Food

Espoma Bulb-tone  Plant FoodEspoma is a popular fertilizer brand that has been producing some quality organic fertilizer since 1929. Here is the best slow-release fertilizer for onions from their tone family. It is an OMRI listed organic fertilizer and it is specially formulated from bulb type flowers and vegetables.

The bulb tone fertilizer contains almost 15 essential plant nutrients including 3% nitrogen,5% phosphate,3% potash,6% calcium,1% magnesium,1% sulfur.The perfect balance of the macro and micronutrients can help your onions to produce a bigger bulb with lush green foliage.

This fertilizer has 2.5% slow-release nitrogen out of 3%. The slow-release fertilizer feeds your onions continuously according to the plant needs and another portion of nutrients comes as a quick-release form that feeds most hungry onion plants quickly.

The nutrients of the bulb tone fertilizer are derived from some organic and natural sources such as feather meal, bone meal. alfalfa meal, greensand, poultry manure, sulfate of potash, and sulfate of magnesia.

Also, this fertilizer has some soil microbes as the non-plant food and 1% humic acid that help to improve soil fertility and revive the plant from some environmental stress.

The bottom line, this is one of the best fertilizer for onion sets that you can also apply bulb flowers including daffodils, Dutch Iris, fritillaria, hyacinth, and other plants of the Allium genus like garlic, leeks, chives, and shallots

Apply 1.5 teaspoons a few inches away from each onion plant. Mix with the surface soil and water the plant to get the desired yield.


3.Burpee Organic Bone Meal Fertilizer

Burpee Organic Bone Meal FertilizerBurpee Organic Bone Meal Fertilizer is the best fertilizer for big onions. So, If you are looking for the perfect fertilizer to produce big onions, it may be the right choice for you. Let’s see what inside the fertilizer-

According to the fertilizer analysis, it has 6% nitrogen,8% phosphate for vegetative growth, and healthy roots and bulb sets. Also, the bone meal provides sufficient calcium that is essential for growing onions.

You may be happy to know; the total amount of nitrogen is water-insoluble nitrogen. That means the water-insoluble nitrogen releases slowly like a slow-release nutrient.

You know; the bone meal is the natural fertilizer that doesn’t contain any inorganic compounds and this fertilizer has nothing without  bone meal. Bottom line; it is the best fertilizer for bulbs with an OMRI certificate.

To apply this fertilizer to your bulb-

Sprinkle ½- 1 teaspoon per onion plant or 1 pound for 40 square feet land. Mix properly and water the plant.


4.Lilly Miller 100099247 Fish Emulsion Fertilizer

Lilly Miller 100099247 Fish Emulsion FertilizerLilly Miller 100099247 Fish Emul Fertilizer is the best liquid fertilizer for onions. If you only produce onion green, it may be the right pick for you. Besides producing the bigger onion bulbs, it also helps you produce bigger onions.

As the plant food,it contains 5% nitrogen,1% phosphate and 1% potash.The 5-1-1 ratio is perfect for healthy onion plants that further produce bigger and healthy onions.

You know; This is the fish fertilizer and it has no inorganic chemicals.OMRI certificate also tells that.

The selling point of the fertilizer is it has 13 plant vitamins that help you to get a healthy, strong, and vigorous plant. Also, this fertilizer stimulates the soil microbes that improve the soil condition and revive the plant from environmental stress.

This fertilizer comes with a concentrated form. Mix 2 tablespoon of concentrated fertilizer per gallon of water and pour around the plant base to feed the nutrients.


5.Homesteader Hobbies Onion Fertilizer

Homesteader Hobbies Onion FertilizerHomesteader Hobbies Onion Fertilizer is the organic fertilizer that is specially formulated for onions. It is an organic and Non-GMO fertilizer. Let’s analyze this fertilizer-

The NPK ratio of this fertilizer is 3-4-3. From the NPK ratio, you can see it has 3 % nitrogen,4% phosphate, and 3% potash. The higher phosphate helps your onion to sets more and bigger bulb and the nitrogen helps you to produce lots of onion green.

Also, this fertilizer contains calcium and plant vitamins that are required to produce healthy and big onions.

All the nutrients and vitamins are derived from some natural and organic sources such as fishbone meal, blood meal, alfalfa meal, feather meal, gypsum, sulfate of potash.

To increase the yield of onions-

Sprinkle 1-2 teaspoons of fertilizer around per onion plant, mix gently, and water the plant.


6. Fox Farm FX14092 Grow Big Liquid Concentrate Fertilizer

Fox Farm FX14092 Grow Big Liquid Concentrate FertilizerFox Farm FX14092 Grow Big Liquid Concentrate Fertilizer is the best fertilizer for onions, tomatoes, peppers, and other vegetables. It is easy to use fertilizer that comes with a liquid concentrated formula.

As the primaray nutrient,this fertilizer has 6% nitrogen,4% phosphate and 4% potash.Also it has 0.6% magnesium,0.02% boron,0.05% copper,0.1% iron,0.05% manganese and 0.05% zinc as the secandary nutrient plant nutrient.

Good news; most of the secondary nutrient contains a chelated coat that protects the nutrient form soil reaction and keeps them always available for the plant.

As you saw, this fertilizer contains most of the required nutrients for growing onions. Also, this fertilizer has kelp that is a natural source of many plant nutrients.

Besides onion, you can also apply this fertilizer to tomatoes, herbs, roses, hibiscus, gardenias, and other bulbs and vegetables.

This fertilizer formulated from some organic chemical but it has no OMRI certificate.

Mix 2-3 teaspoons per gallon of water and pour on the onions plant and beds to get the big onions.


7.Dr. Earth Premium Gold All Purpose Fertilizer

Dr. Earth Premium Gold All Purpose Fertilizer
Dr. Earth Premium Gold All Purpose Fertilizer is another best natural fertilizer for onions. It comes with a balanced NPK ratio that is perfect for all kinds of fruits, flowers, and vegetables.

The NPK ratio of this all-purpose fertilizer is 4-4-4. That means it contains an equal amount of nitrogen, phosphate, and potash and the equal ratio is the onions perfect for onions.

It can also be called the best slow-release fertilizer for onions. Want to know why? Because it contains total 4% of water-insoluble nitrogen that can feed your onion plant slowly.

The nutrients of this fertilizer formulated from alfalfa meal, fishbone meal, bone meal, feather meal, potassium sulfate, kelp meal, and kelp flour.

As you saw, all are organic sources and it is free from the inorganic chemical that is also proved by OMRI and NOP certificate.

The best part of this fertilizer-

It has some beneficial soil microbes and 11% humic acids that make the soil fertilizer and protect the plant from stress.

To apply this pet and environment-friendly fertilizer to your growing onions-

Sprinkle 1 cup per 10 square feet growing areas. Mix gently into the surface soil and water thoroughly.


When to Fertilize Onions?

You should first apply fertilizer when you prepare the soil for onions. Then apply fertilizer after 20 days after planting and reapply every 1-2 weeks.

Remember; the reapplying schedule depends on the fertilizer brand and type of fertilizer. So, read the label of the fertilizer and follow their instructions.

How to Fertilize Onions?

The fertilizing process on onions also depends on the type of fertilizer. Here I am giving you the basic outline that you can follow to apply fertilizer on your onion plants-

Step 1: Measure the Fertilizer

Measuring is the first step. Measure the fertilizer according to the label of fertilizer.

Step 2: Prepare the solution

This step is applicable only for water-soluble and liquid fertilizer. Mix the pre-measured liquid and water-soluble fertilizer into the water.

Step 3: Apply the Fertilizer to Onions

Sprinkle the pre-measured granular fertilizer on the bed or around the onion plant and in case of liquid fertilizer pour the liquid solution on the plants.

Frequently Asked Questions

Can I Grow an Onion from an Onion?

Yes, you can grow onion from the onion. Growing onions from seeds is a lengthy process. So, it is a wise idea to grow onions from sprouting onions. Here is the article that helps you better understand-How to Grow an Onion from Onion-12 steps.

How Many Onions Grow from One Bulb?

Generally, one sprouting onion can grow multiple onions. But sometimes one bulb produces one or two bigger onions.

How Do I Get My Onions to Grow Bigger?

If you want to grow bigger onions, plant the good seedlings in good soil, water, and fertilize the onions regularly. Hope you will get bigger onions.

Is Miracle Grow Good For Onions?

Miracle-Gro fertilizer is also good for onions. But all the Miracle-Gro fertilizers are not perfect for onions. Here is the best onion fertilizer for onions from Miracle-Grow- Miracle-Gro Performance Organics All Purpose Plant Nutrition Granules.

This fertilizer has 9-2-7 NPK ratio and the nutrients are derived from some organic sources. That is also proved by OMRI. This the quick-acting fertilizer. You can see the better result applying after 7 days 

Is Chicken Manure Good for Onions?

Chicken manure is a natural source of nitrogen. So, applying chicken manure while preparing the soil for onions can reduce the 50% nitrogen demand. That means if you add chicken manure in the soil, you don’t need too much nitrogen.

Here is the recommended chicken manure- Espoma Organic Chicken Manure.

Is Bone Meal Good for Onions?

Bone meal is a good fertilizer for onions. Bone meal is the natural source of organic phosphorus and you know phosphorus is essential for strong roots and flowers. That’s why the bone meal is best for root crops like onion, garlic, etc.

Is Potash Good for Onions?

Potash is required for overall plant health and produces bigger onions. But if you want to produce tasty and flavorous onions, then add a little amount of potash.

Do Onions like Blood Meal?

Blood meal is another organic source of nitrogen. The blood meal can raise the nitrogen level in the soil and you know, onions need nitrogen for healthy and green vegetation.

Do Onions like Epsom Salt?

Epsom salt is the natural and organic source of magnesium and onion plants need a little amount of magnesium to produce tasty and flavored onions.


I mentioned all the best fertilizer for onions. All the fertilizers can be applied to the onion without hesitation. Now the choice is yours.

Lately, I would like to tell you, plant your onion in good and loose soil, compact soil reduces production. And must read the label of your fertilizer and follow their instructions.

I hope you will get bigger and tasty onions this time. If I miss anything, don’t hesitate to ask.

Leave a Comment