How to Choose the Best Fertilizer for Garlic

Trying to grow bigger, healthier garlic? The key to growing a plentiful garlic crop starts in the soil. Garlic is a heavy feeder, meaning it requires a rich and well-balanced soil environment to thrive. Whether you’re growing garlic for personal use or commercial production, choosing the right fertilizer can make all the difference. This guide will walk you through the best fertilizers for garlic and how to use them for optimal results.

Garlic Health Starts in the Soil

Garlic’s success begins with the soil. Healthy soil is teeming with microbial life, organic matter, and essential nutrients that promote strong root development and robust bulb formation. Before applying fertilizers, consider testing your soil to determine its pH, organic matter content, and nutrient levels. Without testing your soil, it will be difficult to know what nutrients your soil lacks, and could be detrimental to your garlic’s health.

Ideally, garlic prefers soil with a pH between 6.0 and 7.0, ample organic matter, and balanced nitrogen, phosphorus, and potassium (N-P-K) levels.

Building soil fertility naturally is a key principle of regenerative agriculture and to growing a healthy garlic crop. Cover cropping, compost application, and microbial inoculants help improve soil structure, retain moisture, and increase the availability of nutrients. These methods ensure that your garlic crop gets a strong start while reducing reliance on synthetic inputs.

Chemical vs Organic Fertilizers for Garlic

Once you know what your soil lacks, you can start exploring options for fertilizers to balance your soil to make it ideal for garlic. You have the option of applying the more common synthetic fertilizers, or all natural, organic fertilizers for a more sustainable approach. Let’s explore the two options. 

Chemical Fertilizers

Chemical fertilizers provide a quick boost of nutrients, typically in a synthetic form that plants can immediately absorb. These fertilizers often contain high concentrations of nitrogen, phosphorus, and potassium, which can promote rapid growth. However, there are drawbacks to using chemical fertilizers:

• Soil Degradation: Prolonged use of chemical fertilizers can lead to soil depletion, reducing microbial diversity and organic matter content.
• Environmental Impact: Excess fertilizers can leach into groundwater, contributing to pollution and harming aquatic ecosystems.
• Short-Term Benefits: While chemical fertilizers provide an immediate nutrient boost, they do not improve soil structure or long-term fertility.

Some commonly used chemical fertilizers for garlic include:

• 10-10-10 balanced fertilizers
• Ammonium sulfate (high nitrogen content)
• Superphosphate (high phosphorus content)

All-Natural, Organic Fertilizers

Organic fertilizers offer a sustainable alternative, enriching the soil while providing garlic with essential nutrients. Unlike synthetic fertilizers, organic options work with soil biology to release nutrients gradually, improving soil health over time.

Composted Humus & Manures

Composted materials such as composted humus add organic matter and beneficial microbes, improving soil texture and nutrient retention. Composted manure (such as cow, horse, or chicken manure) provides a slow-release source of nitrogen.

Crab Meal & Kelp Meal 

Keystone Bio-Ag makes an organic fertilizer called Powershell, which is great for nitrogen-loving crops such as garlic, and offers slow release nitrogen that does not contribute to insect susceptibility like nitrate applications do. 

You can also apply kelp meal to help aid root stimulation. If you are looking for something to help boost cytokinin production and the ability for foliar application, you might want to consider giving Seastim a try. 

Alfalfa Meal & Soybean Meal

Alfalfa and soybean meal provide a balanced nutrient profile with natural growth stimulants. These meals decompose gradually, supplying nutrients throughout the growing season.

Fungi & Algae

Microbial inoculants introduce beneficial bacteria and fungi to break down organic matter and enhance nutrient availability. 

When to Fertilize Garlic

Fertilizing garlic at the right time is essential for ensuring strong growth and large bulb development. Different growth stages require different nutrients to support the plant’s changing needs.

At Planting (Fall)

Incorporate compost or manure into the soil before planting cloves. This adds organic matter and nutrients to help establish strong roots. A phosphorus-rich fertilizer, such as bone meal or fish meal, further supports early root development. A root primer should also be considered during this stage. 

Early Spring (Emerging Shoots)

As garlic shoots begin to emerge, applying a nitrogen-rich fertilizer like fish emulsion or alfalfa meal encourages vegetative growth. Side-dressing with compost or worm castings provides a slow-release nutrient boost that keeps the plants strong.

Mid-Spring (Rapid Growth Phase)

Garlic requires consistent nitrogen applications every three to four weeks during its active growth period. Something like kelp meal or Powershell mentioned earlier would be helpful during this stage of growth to offer slow-release nitrogen. 

Bulb Formation Stage (Late Spring to Early Summer)

As bulbs begin to form, it’s important to reduce nitrogen application to prevent excessive leaf growth. Instead, shift the focus to phosphorus and potassium sources, such as bone meal and kelp extract, which promote bulb enlargement.

Why Does Garlic Have Yellow Tips?

If you are noticing your garlic revealing a yellow tip, it is likely because of a lack of nitrogen, molybdenum, water or a combination of the three. We use NatureSafe 7-7-7 and potassium sulfate at this stage through irrigation to prevent/alleviate this. 

Pre-Harvest (Final Weeks Before Harvest)

Fertilization should stop about two to three weeks before harvesting. This allows the garlic bulbs to mature properly and develop their characteristic size and flavor.

Where to Buy Organic Fertilizers for Garlic?

Keystone Bio-Ag is a leader in regenerative agriculture and sustainable fertilization options. Whether you are looking for a dry, granular fertilizer or a liquid fertilizer for foliar applications, Keystone has the right mix for your soil and crops. If you are unsure what the best option is for your crop, Keystone has a team of regenerative ag consultants ready to help you grow bigger, healthier crops.