The Best Fertilizer For Onions Reviewed 2024

Onions require high nitrogen for growth, and they should be watered immediately after feeding to maintain moisture throughout the growing season. In the case of organic fertilizers, the soil should be rich in nitrogen. As onions grow underground, they need specific nutrients that should be present in your manure.

Additionally, there should be frequent watering so they can grow healthy and tasty. This article vividly explains how to plant onions and things to look out for when looking for the best fertilizer for onions. Getting to know the requirements for the growth of onions is further essential. 

Overview of Our Top Choice:

Our best pick is Organic Blood Meal Fertilizer.

How To Plant Onions

Onions can be planted from seeds or tiny bulblets. When it comes to planting seeds, there are a variety of grains to choose from; therefore, select those that are suitable for your region. After getting your seeds, you can plant them in a small area where you can later transplant into more giant cells.

In your garden, you should space them 4-6 inches apart in a raw. Plant them half-inch deep in a small hole. Once you have planted them, you can trim the tops about 4 inches. From there, you should water them continually depending on how dry or wet your region is. Onions can be ready in 20-30 days after planting. Bare onion bulbs take up to 100-175 days to mature.

In cases where mulch is used, regular watering is not necessary. However, the more frequent you water the onions, the sweeter the onions become.

What To Consider When Purchasing The Best Fertilizer For Onions

Fertilizers play a vital role in onion’s growth because it infuses the soil with nutrients that may be lacking for the onions to thrive. However, there are few things to look out for when purchasing your fertilizer.

Soil needs

Before you purchase fertilizer, check out for the soil’s needs in terms of the richness. This is because some soils are fertile, while others are not. That way, you can buy a fertilizer that will match and balance the soil nutrients.

Nutrients present

Nutrients availability is labeled in a number ratio, such as 10-10-10. These numbers represent the ratio of nitrogen, phosphorus, and potassium nutrients available. In the case of onions, you should choose a fertilizer highly rich in nitrogen.

Nitrogen helps plants with proteins they need to produce new tissues. Phosphorus stimulates the growth of roots and helps plants to properly set buds, flowers, and also to increase the seed size. Potassium helps plants to regulate metabolic activities. Ideally, these are the essential nutrients that should be present in every fertilizer.

Micronutrients and ingredients

Apart from primary nutrients that are critical components for the fertilizers, they require extra ingredients such as blood meal, bone meal, guano, and earthworm casing, which promote massively in the growth of onion plants.

Garden size

You don’t want to but insufficient fertilizer that will be too little for your garden. Additionally, knowing your garden size will help you not to buy excess fertilizer that may end up going bad if poorly stored or stays for long. 

Soils ph

Some nutrients cannot be absorbed by plants, even if there are proper nutrients present.  This is because of the soil ph being either too high or too low. Some fertilizer nutrients may adversely affect the soil ph.therefore choose wisely.

What Are The Soil Requirements To Grow Onions?

Organic matter

Soils require higher levels of organic matter, just like other vegetables. Grounds for onions will be best if combined with generous additions of organic matter. However, if you choose to prepare your soil before, ensure that you increase the naturality of the soil. You can do this by adding manure.

Muck soils are best known to have a high organic matter, which makes them ideal for commercial onion farming. You can blend in weeds, fresh manure vegetables, or other deciduous leaves to increase your soil’s organic matter.

The soil ph

The soils ph represents the level of acidity or alkalinity in the land. Onions love neutral soil ph. Sending your soil sample to a testing agency is the only reliable way to achieve your soil pH effortlessly.

High nitrogen level

It’s worth noting that onions thrive well in highly nitrogenous soils. The decaying matter in the soil provides nitrogen. Ideally, if you choose to use onion fertilizers, choose one that has high nitrogen levels. Nitrogen helps to ensure the onions grow strong, and the root system thrives. Nitrogen helps the onions to create new cells, which later organize into plant tissue.

Minor nutrients

Onions may fail to reach their optimum yield and quality without adequate supplies in minor nutrients. The soil contains beneficial microbes that help the onions thrive. Bacteria are not enough, and therefore you should ensure your land includes micronutrients such as zinc since plants only require small amounts.

The Best Fertilizer For Onions Reviewed

1. Worm Castings Organic Fertilizer

Worm Castings Fertilizer is organic with pure earthworm casting excellent for houseplants, vegetables, flowers, and many more. Earthworm casting is mother nature’s best-growing secret because you just require to use a small amount around your plant. The results are seen in the healthy growth and yields of your plant. 

It entails perfectly balanced nutrients in two designs. One that is instantly absorbed by the plant-like has been applied directly, and the other provides nutrients feeding the plant slowly for a long time.

Worm Castings Fertilizer is a soil builder that is cost-effective as you only need a small amount of it to have beautiful results for an extended period. Pure earthworm castings are designed with water-soluble nutrients, which results in incredible outcomes. It’s formulated with a high concentration of essential bacteria and microbes beneficial to different elements of the soil work to create healthy, working soil that provides the best environment for optimum growth.


  • It can improve the soil structure, allowing roots to grow fast and fibrous, promoting rapid growth.
  • Small amount ends in excellent results
  • Plentiful of nutrients to feed the plant for a long time
  • Has natural nutrients


  • Not suitable for acid-loving plants
  • It takes time to absorb

Last update on 2024-07-13 / Affiliate links / Images from Amazon Product Advertising API

2. Dr. Earth Home Grown Herb Fertilizer

Dr. Earth Fertilizer produces excellent results because nutrients are released quickly but continue to feed the plant for a more extended period. It’s designed to feed vegetable gardens, summer and winter crops, and container plantings or native backyard soil. Usable during the first stages while planting seeds, transplanting, and frequently as a top dresser or compost tea.

Dr. Earth Home Grown Fertilizer results in tasty, healthy, and big fruits and can be used for both outdoor and indoor planting.  Additionally, it is rich in various nutrients entirely. It’s excellent for foliar and root-feeding, producing higher yields, more flavorful fruits, and at the same safe to use because it uses an utterly organic source of nutrients.


  • Safe for people and pets.
  • Improves the onions taste
  • Eliminates the need for chemical fertilizers
  • Easy to use and handle


  • It’s expensive compared to its counterparts
  • Mold growing after application

Last update on 2024-07-13 / Affiliate links / Images from Amazon Product Advertising API

3. Organic Blood Meal 50lb Bag Fertilizer

Organic Blood Meal Fertilizer has all the necessary nutrients that are highly important for your plant’s growth. It is natural and pure, and it can act as an insecticide for removing all insects and pests from the garden. They are designed as slow-release fertilizers with an excellent NPK ratio.

Some part of it is absorbed instantly while the other part stays nourishing the plant for a more extended period. Organic Blood Meal Fertilizer quickly adds nitrogen to the soil that will help your onions grow lusher. This is because onions are heavy nitrogen feeders; therefore, the blood meal will ensure that nitrogen is present in the soil.


  • Highly rich in nutrients that aid the plant to reproduce and remain healthy
  • Slow-release fertilizer
  • Nourishes plants for extended periods
  • Acts as a pesticide removing all insects and pests from the garden


  • It’s expensive
  • Not meant for heavy-duty plantation jobs

4. Lilly Miller Morcrop Fertilizer

Lilly Miller Morcrop Fertilizer has the perfect nutrient composition fit for onions. It helps in the quick and smooth growth of healthy, vigorous plants. It also incorporates the slow release method for lush and steady growth. Natural ingredients in this fertilizer promote the growth of plants. Additionally, they are cost-effective, which makes it easy for you to purchase.

Lilly Miller Morcrop Fertilizer is further ideal for the growth of high-tasting vegetables. Proper blending of natural ingredients with traditional plant foods enhances the production of a unique fertilizer that provides nitrogen from five different sources.

These ingredients are well mixed for plants to start actively. In addition to this, it entails extra minerals so ensure your onions never go hungry for these elements.


  • Slow-release for the steady growth of onions
  • Feature natural ingredients
  • NPK 5-10-10 ratio appropriate for the growth of vegetables.
  • Availability of extra minerals
  • It’s ready to use fertilizer hence no need to mix with water


  • Sometimes the nutrients level may be low

Last update on 2024-07-13 / Affiliate links / Images from Amazon Product Advertising API

5. Natural Alternative All-Purpose Fertilizer

Natural Alternative All-Purpose Fertilizer, just as the name dictates, it entails natural ingredients. It can cover a garden space up to 200 square feet. Don’t worry when you are transplanting your onions as it protects them against transplant shock. Available mycorrhiza fungi and beneficial microbes help the plant to fight pathogens.

Natural Alternative Fertilizer is applied every four weeks continuously for beautiful results. Available built-in shaker makes the application in larger areas effortless. Available calcium, magnesium iron, among other micronutrients, help the onions to thrive. You can expect the growth of healthy roots that result in healthy plants when using this fertilizer.


  • Ensures maximum protection of the plant during transplanting
  • Fortified with beneficial microbes to aid in the health of the soil
  • Covers a large area


  • Too much of this fertilizer may weaken the plant’s growth

Last update on 2024-07-12 / Affiliate links / Images from Amazon Product Advertising API


Onions require a fertilizer that has a high nitrogen percentage. The first thing that onions do after transplanting is to shoot new roots. Therefore, the compost should be mild enough for new roots and protect them from transplant shock.

Best fertilizers for onions should also contain micronutrients that help the plant to thrive. Additionally, organic fertilizers are the best for onion growth because they entail natural and pure ingredients fit for onions.

Our best pick is Organic Blood Meal Fertilizer. It has the best conditions and high nitrogen levels for the growth of onions. Also, if you are replanting the same garden year after year, blood meal is essential since plants tend to deplete in the soil. Ideally, critical to implement a fertilizer that adapts to these conditions to help you achieve optimum yields.

As onions grow underground, they need specific nutrients that should be present in your manure. This article will show you how to grow onions and share some tips on what to look out for when looking for the best fertilizer for onions. Getting to know the requirements for the growth of onions is further essential.  Learn more about gardening tips @ #GardeningStuffs
If you want your onions to grow healthy and tasty. Check out this guide, we’ll explain how to plant onions and what soil requirements that onions need.
Check out our article on how to plant onions and things to look out for when looking for the best fertilizer for onions. Getting to know the requirements for the growth of onions is further essential.