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  • Writer's pictureJere Folgert

Optimize Fertilizer Applications For Garlic!

Updated: May 12

Garlic plants have specific needs - light, air, water, space to grow, and essential nutrients - to survive and reproduce. Let's focus on the nutrients garlic plants need to thrive. There are 17 essential nutrients that all plants need, including nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, chlorine, iron, manganese, zinc, copper, molybdenum, and nickel. The non-mineral essential plant elements include hydrogen, oxygen, and carbon. These seventeen essential nutrients are taken up by plants from air, soil and water. Nitrogen, phosphorus, and potassium (NPK) are needed in larger amounts than other nutrients; they are considered primary macronutrients. Secondary macronutrients include sulfur, calcium, and magnesium. Micronutrients such as iron and copper are necessary in much smaller amounts. With the right amount of nutrients, your garlic crop can thrive and provide pounds of produce for harvest.

Here are some tips on how to optimize fertilizer for plants:

  1. Test your soil. The first step to optimizing fertilizer for plants is to test your soil. This will help you to determine the nutrient levels in your soil and whether or not you need to add any fertilizer. You can test your soil at home or at a local garden center.

  2. Choose the right type of fertilizer. There are many different types of fertilizers available, so it is important to choose the right type for your plants. Ideally, select an organic fertilizer instead of the man-made synthetic fertilizers. The type of fertilizer you need will depend on the type of plants you are growing, the pH of your soil, and the climate you live in.

  3. Apply the fertilizer correctly. Once you have chosen the right type of fertilizer, you need to apply it correctly. The amount of fertilizer you need to apply will depend on the type of fertilizer you are using, the size of your plants, and the stage of growth they are in. You should also follow the directions on the fertilizer label carefully.

  4. Water your plants after fertilizing. After you have fertilized your plants, you need to water them well. This will help to distribute the fertilizer evenly and prevent it from burning your plants.

  5. Monitor your plants. After you have fertilized your plants, you need to monitor them to make sure they are healthy. If you notice any problems, such as yellowing leaves or stunted growth, you may need to adjust the amount of fertilizer you are using.

How do we, as garlic growers, optimize fertilizer applications so our garlic will thrive and produce large garlic bulbs? Here are a few ways to ensure optimum nutrients in the field and garden.

TEST SOIL, AND OFTEN. Our First Task in optimizing fertilizer applications is to perform a soil test. The soil test should be performed at least once each year. The Soil Test is important for several reasons: to optimize crop production, to protect the environment from contamination by runoff and leaching of excess fertilizers, to aid in the diagnosis of plant culture problems, to improve the nutritional balance of the growing media and to save money and conserve energy by applying only the amount of fertilizer needed for your garlic crop. Determining the pH and fertility level through a soil test is the first step in planning a sound nutrient management program. The fertilizer you choose should be based primarily on soil test results and garlic plant needs, both in terms of nutrients and speed of delivery.

KNOW YOUR SOIL TYPE. We need to understand how our soil type, soil texture and soil pH can determine how nutrients are taken up by the garlic plants. Some nutrients such as phosphorus (P) moves through the soil slowly in the range of a few millimeters each year.

Nutrient availability: Every part of the country has unique soil conditions. Some soils have adequate calcium, magnesium, sulfur and micronutrients to support healthy garlic plant growth. Nitrogen, phosphorus, and potassium are the nutrients most likely to be deficient in soils and should be supplemented with fertilizers for optimum plant growth. The best method for determining what nutrients are needed in your garden is to do a soil test. A basic soil test can be ordered on-line. If possible, check with a soil lab at the University in your state. At GROeat Farm, we have used Agvise Laboratoires located in North Dakota and Minnesota. Other mail-in laboratories include groSMART, and Western Materials Testing. The analysis will provide a basic interpretation of the results and provide recommendations for fertilizing.

Soil Texture: Nutrient availability in soils is a function of many factors including soil texture (clay, loam, loamy sand, silt loam), organic matter content and pH. Clay particles and organic matter in soils will hold and slowly release nutrient ions that can be used by garlic plants. For example, sandy soils with little or no clay or organic matter have less nutrient-holding ability than soils that are finer-textured (more clay) and higher in organic matter.

pH: Soil pH is the level of alkalinity or acidity of soils. When pH is too low or too high, the chemical reactions occurring in the soil can reduce the nutrient availability and biological activity in soils. Most hardneck garlic plants grow best when the soil pH is slightly acidic to neutral, or between 6.0 and 7.0.

MATCH FERTILIZER APPLICATION BASED ON SOIL TEST AND CROP. There are many options for fertilizers and sometimes the choices may seem overwhelming. If you paid for a soil test, many laboratories will recommend a fertilizer application based on your crop and the results of the soil test. When submitting soil to be tested, be sure to let them know you are growing garlic. The most important thing to remember is that plants take up nutrients in the form of ions, and the source of those ions is not a factor in plant nutrition. Garlic plants take up nitrogen compounds through their roots. When plants and animals die or when animals excrete wastes, the nitrogen compounds in the organic matter re-enter the soil where they are broken down by microorganisms, known as decomposers. Plants get nitrogen via NO3- (nitrate) or NH4+ (ammonium), and those ions can come from either organic or synthetic sources and in various formulations (liquid, granular, pellets or compost). All commercially available fertilizers have what is called a guaranteed analysis, meaning the percent of each major nutrient, by weight, in the fertilizer must be listed on the package as N-P-K. For example, 10 pounds of 20-18-17 garden fertilizer contains 2.0 pounds of nitrogen, 1.8 pounds of phosphorus oxide (P2O5 – phosphate), and 1.7 pounds of potassium oxide (K2O – potash). If you cannot find a fertilizer with the exact N-P-K ratio that is recommended by your soil test report, you should select a product with a ratio that most closely matches. It’s more important to match the nitrogen recommendation than the phosphorus or potassium recommendation, but try not to exceed the phosphorus recommendation because of water quality concerns.

If Our Garlic Plants Lack Certain Nutrients, What Will I See? Plants lacking nitrogen will likely show yellowing on older, lower leaves. Too much nitrogen can cause excessive leafy growth and smaller garlic bulbs. We do not want our garlic to be as tall as a corn plant! Because nitrogen promotes leafy growth, too much nitrogen late in the season can minimize bulb creation. Nitrogen is considered to be mobile in the soil, meaning that it moves with water, so it’s best to apply nitrogen when plants will be ready to use it. Plants lacking phosphorus may show stunted growth or a reddish-purple tint in leaf tissue. A potassium deficiency can cause browning of leaf tissue along the leaf edges, starting with lower, older leaves. Phosphorus and potassium are not mobile in the soil and need close contact with plant roots in order to be taken up. They should be applied and incorporated prior to planting, either in spring or fall. Among other things, phosphorus supports root growth, while potassium supports disease resistance and plant hardiness. A calcium deficiency often leads to “tip burn” on younger leaves. However, calcium deficiencies are often not a result of low calcium in the soil, but are caused by uneven watering, excessive soil moisture, or damage to roots. Lack of sulfur on sandy soils can cause stunted, spindly growth and yellowing leaves. One of the most important active compounds in garlic is alliin. Sulfur (S) fertilization was shown to significantly increase the alliin concentration in garlic cloves, while high nitrogen (N) levels had an adverse effect. The two forms of Sulfur include sulfate S (SO₄²⁻) and elemental S (S⁰). Sulfate sulfur is available immediately to the crop while S⁰ oxidizes for late-season sulfur uptake by the plants. Plants can absorb S only through their root systems in the SO₄²⁻ form. Too much sulfur can be toxic to garlic plants, so don't add too much. Sulfur Toxicity in Plants results when too much sulfur is in the soil. Sometimes, high concentrations of sulfur can cause an increase in salts. This can accumulate and cause your plants to become stunted and dark in color. Excess sulfur in the soil that creates fertilizer salts can also burn the roots of the plants.

USE THE 4 "Rs" AS A GUIDE. These include "Right Source", "Right Rate", "Right Time", and "Right Placement". The results of your soil test should provide you with simple guidance on the rate, timing, source, and placement of any required fertilizers.

ADD ORGANIC MATTER TO YOUR SOIL. Regardless of which fertilizers you choose. Adding organic materials to your soil can most certainly result in bigger garlic. Incorporating organic materials can actually reduce the need for supplemental fertilizers. Organic matter such as compost support overall soil health. Carbon-based materials such as organic fertilizers, compost, leaves, grass clippings or cover crops provide a range of benefits to both plants and soil. One of the reasons we add organic materials to soils is because they contain other essential plant nutrients in addition to N, P and K. Organic materials provide food to feed soil microorganisms, which also increases soil organic matter. Adding organic materials to soil also helps the soil retain moisture and facilitates drainage and aeration in many soil types. In simple terms, you want to feed your garlic plants, but you also want to make sure that the microbiome, those tiny little critters living in your soil, are happy and have a reason to party. Building healthy soil solves many parts of the equation.

AVOID SYNTHETIC FERTILIZER.  While synthetic fertilizers offer a quick nutrient boost, their long-term effects can be detrimental to both plant health and the environment.  These fertilizers often contain heavy metals like cadmium or arsenic, which can accumulate in the soil and potentially contaminate the garlic itself.  Furthermore, their production requires significant energy, contributing to a larger carbon footprint.  Perhaps most concerning is their impact on soil health. Synthetic fertilizers can disrupt the delicate balance of soil microbes, essential for nutrient cycling and plant growth.  This disrupts the natural breakdown of organic matter, a crucial food source for these microbes.  The readily available nutrients in synthetics can also create a "sugar rush" for plants, prioritizing rapid top growth over bulb development in garlic.  In contrast, a soil teeming with microbial life, fostered by organic matter and organic fertilizers, creates a thriving ecosystem.  These microbes break down organic materials, releasing a sustained and balanced supply of nutrients that garlic readily absorbs. This approach not only promotes healthy bulb formation but also protects the environment and fosters a more resilient, biodiverse garden.

ADD AZOMITE.  Supplementing garden beds with Azomite, a volcanic rock dust, may positively influence the growth of hardneck garlic. Azomite boasts a rich composition of over 70 trace minerals, including boron, manganese, and molybdenum. Boron strengthens cell walls, crucial for healthy bulb development. Manganese plays a role in photosynthesis, which provides energy for plant growth. Molybdenum is essential for nitrogen fixation, a process that converts atmospheric nitrogen into a usable form for garlic to build proteins and enzymes. By providing this diverse range of trace minerals, Azomite has the potential to improve nutrient uptake, enhance disease resistance, and promote larger, more flavorful garlic cloves in hardneck varieties.

AVOID EXCESSIVE APPLICATIONS  Excessive fertilizer application on garlic plants can be detrimental and counterproductive. While garlic is a feeder crop requiring sufficient nutrients, an overabundance, particularly nitrogen, disrupts the plant's resource allocation.  High nitrogen levels promote excessive top growth, causing the plant to prioritize foliage production over bulb development. This can lead to scenarios where the garlic plant boasts impressive, corn-like stalks, but the underground bulb, the desired product, remains underdeveloped and small.  To optimize growth and harvest, a soil test is crucial. This analysis provides a data-driven approach to fertilization, ensuring that only deficient nutrients are replenished, preventing waste and potential harm to the garlic plants.


Optimizing Fertilizer for Your Garden

Fertilizer is an important part of any garden, but it's important to use the right type and amount of fertilizer for your plants. Too much fertilizer can damage your plants, while too little fertilizer can stunt their growth. The first step to optimizing fertilizer for your garden is to test your soil. This will help you to determine the nutrient levels in your soil and whether or not you need to add any fertilizer. You can test your soil at home or at a local garden center.

Once you know the nutrient levels in your soil, you can choose the right type of fertilizer. There are three main types of fertilizer: nitrogen, phosphorus, and potassium. Nitrogen helps plants grow green leaves, phosphorus helps plants produce flowers and fruit, and potassium helps plants resist disease and pests.

You can find fertilizers that contain all three of these nutrients, or you can choose a fertilizer that is high in one particular nutrient. The type of fertilizer you need will depend on the type of plants you are growing. For example, vegetables that produce fruit, such as tomatoes and peppers, need a lot of phosphorus. Once you have chosen the right type of fertilizer, you need to apply it correctly. The amount of fertilizer you need to apply will depend on the type of fertilizer you are using, the size of your plants, and the stage of growth they are in. You should also follow the directions on the fertilizer label carefully. It's important to water your plants after fertilizing. This will help to distribute the fertilizer evenly and prevent it from burning your plants.

Finally, you should monitor your plants after fertilizing. If you notice any problems, such as yellowing leaves or stunted growth, you may need to adjust the amount of fertilizer you are using.

By following these tips, you can optimize fertilizer for your garden and help your plants grow healthy and strong.

Here are some additional tips for optimizing fertilizer for your garden:

  • Fertilize in the spring and early summer. This is when plants are actively growing and can use the nutrients most effectively.

  • Apply fertilizer to wet soil. This will help to prevent the fertilizer from burning your plants.

  • Don't overfertilize. Too much fertilizer can damage your plants.

  • Use organic fertilizer. This will provide your plants with the nutrients they need without overdoing it.

  • Fertilize according to the needs of your plants. Some plants need more fertilizer than others.

  • Experiment to find what works best for your garden. Different types of soil and plants respond differently to fertilizer.

  • Use organic fertilizers whenever possible. These fertilizers are less likely to harm the environment.

  • Read the label carefully. Follow the directions on the fertilizer label to ensure proper application.

  • Store fertilizer in a safe place. Keep fertilizer out of reach of children and pets.

Mr. Jere Folgert is the owner of GroEat Garlic Farm in Bozeman, Montana. GroEat Farm is a small, sustainable family farm located in the beautiful Hyalite Foothills, in the shadows of the Gallatin Mountain Range. The hardneck varieties that they grow on their farm flourish, due to the combination of the very cold winters, heavy snowpack, moist spring, temperate summers, and the nutrient-rich and dynamic alluvial soils, washed down from the Gallatin Mountain Range.

A Story of Fertilizer

"Alexis, a vision of sunshine with her cascading blonde hair, possessed a magic touch when it came to her garden. Years of studying plant biology and science had instilled in her a deep appreciation for the intricate dance between soil, sunlight, and sustenance. Alexis wasn't just growing vegetables; she was nurturing life, a passion evident in the vibrant greens and plump tomatoes that spilled from her raised beds.

One crisp spring morning, Alexis noticed her neighbor Mere fretting over a forlorn patch of garlic. Mere, a kind woman with a perpetually worried brow, had a history of battling underwhelming harvests. Alexis, ever the generous soul, couldn't resist offering a helping hand.

"Mere," Alexis called out, a smile blooming on her face like a morning glory, "having some trouble with your garlic?"

Mere's shoulders slumped. "It just never seems to take off! I follow the instructions on the bag, but the bulbs are always puny."

Alexis crouched down, examining the soil. "Mere, have you ever considered a soil test? Knowing your nutrient baseline is crucial for targeted feeding."

Mere's eyes widened. "A soil test? Is that expensive?"

Alexis chuckled. "Not at all! It's like a roadmap for your plants, telling you exactly what they need to thrive."

Intrigued, Mere agreed. The results were an eye-opener. Mere's soil lacked essential components like phosphorus and potassium, while the bag fertilizer she'd been using was heavy on nitrogen. Alexis explained how excess nitrogen could be a sneaky villain, promoting lush green foliage at the expense of bulb development.

Together, they formulated a plan. Alexis introduced Mere to the wonders of organic matter, teaching her how compost and aged manure could work wonders for soil health. They also selected a fertilizer specifically designed for garlic, ensuring a balanced supply of nutrients.

The following year, Mere's garden boasted the most magnificent garlic crop either of them had ever seen. Fat, glistening bulbs pushed through the soil, a testament to their combined knowledge. To celebrate, they turned their bounty into a culinary adventure. Black garlic, with its sweet, smoky depth, became the star of a gourmet pasta dish, infused with the fragrant essence of their success. As they savored their creation, Alexis and Mere laughed, the joy of gardening and newfound friendship mingling in the air, as sweet and heady as the garlic itself."

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