Organic Garlic Fertilizer Requirements

Soil Preparation

• Organic garlic follows the same fertilizer requirements that apply to organic onions, which need full sun and nutrient-rich soil to grow and develop. The ideal pH levels for garlic range from 6.8 to 7.2. The plant grows best in friable, loamy soil that breaks apart in your hand with ample drainage. In addition, garlic should be planted in soil that consists of a significant amount of organic matter, which promotes moisture retention and drainage.

  Prepare the soil for propagation with animal or green manure a year or two before you actually plant garlic seeds (cloves). Soil preparation helps to improve the soil's organic matter content and nutrient levels.

Slow-Release Fertilizer with Nitrogen in the Fall

• Organic garlic requires a fall application of a slow-release fertilizer, such as soybean meal, that contains nitrogen. Ohio State University recommends using an organic fertilizer that contains a ratio of 10-10-10 with equal parts nitrogen, phosphate and potassium (NPK). The fertilizer should be applied at a rate of 3 lbs. for every 100 square feet. Do not use a soluble nitrogen fertilizer in the fall, since it can cause ground water contamination and nitrogen loss from leaching.

  Never fertilize your garlic when the bulbs start to expand, as nutrients fed to crops at this point in the development process can cause excessive leaf growth and impact the size of bulbs.

Balanced Fertilizer in the Spring

• Fertilize organic garlic in the spring when the ground thaws with an organic fertilizer similar to one used in the fall application. Apply an organic fertilizer with a 10-10-10 NPK nutrient balance, like soybean meal or seaweed and liquid fish foliar sprays, during the fourth or fifth leaf development stage and before the end of May to enhance plant growth and development.

  Avoid fertilizing organic garlic crops after May, as nitrogen soil levels are usually highest in the late spring and summer. Organic fertilizers applied in June can decrease the bulb size.