Onions & Garlic
Onions and garlic belong to the Allium family. These plants are known for their pungent flavor and smell and are valued for various culinary uses. Both onions and garlic require a well-balanced fertility program to support both crop productivity and quality. A well-managed nutrient plan to support bulb development and plant health can help set the crop up for better yields and longer storage times. At Tessenderlo Kerley, we have several products that can help reach these crop health goals.
Our fertilizer portfolio will successfully address your crop nutrition needs by providing immediately available nutrients to the plant. Here are some suggestions for using our fertilizers when growing onions and garlic.
Nitrogen
Nitrogen is essential for onion and garlic production because it drives vigorous vegetative growth, which is critical for developing healthy bulbs. Adequate nitrogen ensures strong leaf development, which directly influences bulb size and quality. However, timing and rate of application are crucial, too little nitrogen at early growth stage can dramatically reduce yield. However, too much nitrogen late in the season can lead to excessive vegetative growth when the plant’s focus should be on bulb development. This can delay maturity and potentially reduce storage life. Balanced nitrogen management helps achieve optimal yield and high-quality bulbs.
N-Sure® contains nitrogen in the Triazone form. In the soil, triazone is slowly released through microbial activity. Including a slow-release nitrogen solution like N-Sure, with more readily available forms of nitrogen (i.e. urea, ammonium and nitrate) can help provide consistent N availability throughout the growing season. This leads to the following:
- Sustained vegetative growth for uniform bulb development
- Potentially reduces N loss to volatilization and leaching
- N-Sure is compatible with both foliar and fertigation programs
Potassium
Potassium plays a vital role in onion and garlic production by supporting water regulation, enzyme activation, and carbohydrate transport within the plant. Adequate potassium improves bulb size, firmness, and overall quality, while also enhancing disease resistance and stress tolerance. Potassium is especially important during bulb development. Tessenderlo Kerley internal research has shown that application of K starting at bulb expansion has improved size of both onion and garlic. Balanced potassium nutrition ensures strong plants and market-ready bulbs. KTS® and K-Row 23® are two potassium products that provide sulfur and potassium to support these key functions in onion for overall health, quality and yield.
A potassium thiosulfate solution that is highly available for balanced nutrition
- Highly soluble and chloride free
- Improves crop ability to cope with drought stress and effectively utilize nitrogen
- Improves phosphorus, calcium, and micronutrient availability in calcareous soils
- Blends easily with other liquid fertilizers including UAN and APP (see application guide for more information)
- When added to UAN solutions, KTS can provide nitrification inhibition to prevent nitrogen loss
Add potassium and sulfur safely in-furrow and on low pH soils
- Highly soluble and chloride free
- Designed as a starter fertilizer for in-furrow applications
- Will not further acidify the soil, can be used on low pH soils
Calcium
Having adequate calcium levels for onions and garlic will result in better yield and improved storability. Calcium can often be abundant in soil, but it’s not always plant available. Applying a soluble calcium fertilizer in-season, typically after bulb initiation with a soluble source of calcium will ensure that the nutrient is there when the crop needs it to build strong cell walls. Additionally, since calcium can help improve soil physical properties, later season applications of calcium have been shown to increase soil tilth. This can make it easier to harvest both onions and garlic, and can sometimes reduce damage when harvesting.
CaTs® is a 100% water-soluble calcium fertilizer that also has thiosulfate to provide essential sulfur nutrition. It can be applied through the irrigation water at critical growth and plant uptake times.
- Contains thiosulfate-based sulfur which helps soil calcium availability
- Improves cell wall strength and shelf life when applied at the peak calcium uptake
- When applied with urea fertilizers it can reduce NH4 volatilization losses
- Effective at leaching harmful salts
Sulfur
The aroma and flavor found when eating an onion is partly due to sulfur. Not only an important nutrient for flavor profiles, but sulfur also influences yield and stress tolerance. Applying sulfur to an onion and garlic crop can be an important part of the program for enhancing nitrogen use efficiency and hitting yield and quality goals.
Thio-Sul® is an excellent source of highly soluble sulfur. It blends easily with other fertilizers including UAN or other urea-based fertilizers. It can help slow down nitrification and volatilization in banded or broadcast applications. This can help reduce nitrogen loss while also providing sulfur.
- Can be used to target ideal N:S ratios when added to UAN blends
- Contains thiosulfate form of sulfur that helps improve nutrient availability such as Phosphorous, Calcium, and micronutrients (Iron, Zinc, Molybdenum, and Copper)
Protect Onions from Heat Stress, Sunburn, and Thrips Pressure
Onion crops can face multiple environmental and pest-related challenges throughout the growing season. Excessive heat and intense sunlight can increase the risk of sunburn, reduce plant performance, and contribute to yield and quality losses. At the same time, onion thrips can damage foliage through feeding, reducing photosynthetic capacity and plant vigor while increasing the risk of Iris Yellow Spot Virus (IYSV) transmission. These stresses often occur simultaneously during hot, dry conditions, making it important for growers to implement management practices that protect both crop health and bulb quality. An integrated approach that addresses environmental stress and pest pressure can help support stronger crop performance through harvest.
Surround® Agricultural Crop Protectant forms a protective particle film on onion leaves that helps reduce heat stress and sunburn while also suppressing onion thrips as part of an integrated pest management program. By reflecting ultraviolet and infrared radiation, Surround helps lower plant temperatures and support plant functions during periods of heat stress. Research and commercial experience have also shown that early-season applications can help suppress thrips populations when coverage is maintained throughout the season.
Build a Strong Foundation for Onion Yield Potential
Successful onion production depends on strong early root development and a healthy soil environment. Soilborne pathogens, nematodes, and weeds can interfere with establishment, reducing the crop's ability to efficiently access water and nutrients throughout the growing season.
Sectagon®-42 and Sectagon®-K54 help growers reduce soilborne pest pressures before planting by targeting a broad range of weeds, diseases, and nematodes. Starting with a cleaner field environment helps lay the foundation for uniform emergence, healthy root systems, and improved crop development.
Season-Long Insect Management for Onions
Onion thrips remain one of the most economically important pests in onion production. Feeding damage can reduce photosynthetic efficiency, weaken plants, and negatively affect bulb quality and yield.
Lannate® helps growers manage onion thrips through contact and translaminar activity, allowing for improved coverage and pest control throughout the canopy. Fast activity helps reduce feeding damage and protect crop quality during key growth stages.
Recommended Blogs
-
Recommended Products
- Thio-Sul® - 12-0-0-26S
- KTS® - 0-0-25-17S
- K-Row 23® - 0-0-23-8S
- CaTs® - 0-0-0-10S-6Ca
- N-Sure® - 28-0-0
- Surround® - Agricultural Crop Protectant
- Sectagon®-42 - Agricultural Fumigant
- Sectagon®-K54 - Agricultural Fumigant
- Lannate® - Insecticide
-
Additional Resources
Check out our library of content geared towards teaching the best crop nutrition practices to growers around the world.
-
Get Local Support
If you're looking for further insights on how Tessenderlo Kerley fertilizers can help you achieve your yield goals, reach out and a Tessenderlo Kerley Specialist will get back to you as soon as possible!