For the best onion fertilizers, I would start with TPS Nutrients Liquid Onion Fertilizer, 8 fl oz as the best overall pick for growers who want an onion-specific liquid in a small, manageable bottle. Jobe’s Organics Granular Bone Meal offers a slower-release, soil-focused alternative, while Old Cobblers Farm Wicked Growth Garlic and Onion Fertilizer, 20 lb suits larger planting areas. The main tradeoff is between liquids that are easy to apply in measured doses and granular products that cover more soil with less frequent application. Crop-specific blends may simplify feeding, but a larger container can be unnecessary for a small garden. Continue reading for the full breakdown and help matching a fertilizer format to your onion-growing setup.
Get garden gear delivered free with Prime
- Fast, free delivery on millions of items
- Prime Video, Amazon Music and more included
- Member-only deals all year
Complete the kit
Key Takeaways
- TPS Nutrients 8 fl oz leads as a compact onion-specific liquid; the 32 fl oz version is the more sensible format for repeat use or a larger planting.
- Jobe’s Organics Bone Meal stands apart as a granular, soil-building choice rather than a liquid feed, so it suits gardeners who prefer working amendments into beds.
- Old Cobblers Farm’s 20 lb bag is aimed at broader coverage, while its bulb-crop plant food is framed for onions, shallots, and leeks.
- Gardenera and Prevegenics add liquid onion-fertilizer alternatives, giving buyers more choice in bottle size and product formulation.
- The strongest choice depends on garden scale and feeding style: a small liquid bottle limits leftover product, while bulk granules or larger liquids make more sense for repeated use.
| onion fertilizer | Brand | Form |
|---|---|---|
| TPS Nutrients Liquid Onion Fer | TPS Nutrients | Liquid |
| Gardenera Liquid Power Onion F | Gardenera | — |
| Jobe’s Organics Granular Bone | Jobe’s Organics | Granules |
| Prevegenics Onion Fertilizer | — | — |
| Old Cobblers Farm Wicked Growt | Old Cobblers Farm | Granules |
| TPS Nutrients Liquid Onion Fer | TPS Nutrients | Liquid |
| Old Cobblers Farm Wicked Growt | — | Granular |
More Details on Our Top Picks
TPS Nutrients Liquid Onion Fertilizer, 8 fl oz
For a small onion bed or a few containers, TPS Nutrients’ 8-ounce concentrate offers a straightforward allium-focused option without committing to a large bottle. Its stated dilution—1 tablespoon per gallon of water—gives gardeners a clear starting point, and the formula is described as supporting roots, foliage, and bulb development. Unlike Jobe’s Organics Bone Meal, which supplies phosphorus and calcium in granules, this liquid can be mixed into a watering routine and is also listed for garlic and other alliums. The tradeoff is limited product detail: the supplied information gives no nutrient analysis, so buyers cannot compare its nutrient balance precisely or tailor it against a soil test. It also needs measuring and dilution before application, making it less convenient than a ready-to-use product.
Pros:- Formulated for onions, garlic, and other alliums
- Described as supporting roots, foliage, and bulb development
- Suitable for garden beds, raised beds, and containers
- Provides a specific dilution rate of 1 tablespoon per gallon
Cons:- Must be diluted and measured before application
- No nutrient analysis is provided for precise comparison or soil-test-based planning
Best for: Container growers and gardeners tending a small onion or mixed-allium planting who want a compact liquid concentrate with a stated dilution rate.
Not ideal for: Gardeners managing a large onion plot or choosing fertilizer by exact NPK values; the 8-ounce bottle is compact, and no nutrient analysis is provided.
- Brand:TPS Nutrients
- Form:Liquid
- Volume:8 fl oz
- Target plants:Onions, garlic, and other alliums
- Mixing ratio:1 tablespoon per gallon of water
- Suitable settings:Garden beds, raised beds, and containers
- Country of manufacture:USA
Our verdict“Choose this compact concentrate for a small allium planting if you value a clear mixing rate more than a disclosed nutrient analysis.”
Gardenera Liquid Power Onion Fertilizer Concentrate, 8 fl oz
Gardenera Liquid Power is the most specification-driven small liquid option here: its onion-focused formula includes chelated micronutrients intended to improve nutrient availability, alongside support for roots, bulb development, and upright foliage. That gives it a different appeal from TPS Nutrients Liquid Onion Fertilizer, whose supplied details describe allium benefits but do not disclose a nutrient analysis or micronutrient approach. Gardenera’s stated 3:1:2 mixing ratio and approximate pH of 1.69 call for more care, though: the product information says it is very acidic, and buyers may need to confirm the intended mixing directions before use. It suits gardeners comfortable handling a concentrate and following product guidance, but is a less forgiving choice for someone seeking simple, fully clear instructions. The 8-ounce volume also favors modest plantings over broad acreage.
Pros:- Formulated specifically for onions
- Includes chelated micronutrients intended to improve nutrient availability
- Described as supporting root growth, bulb development, and upright foliage
- Suitable for pots and garden plots
Cons:- Very acidic formulation calls for careful handling
- The supplied mixing information may need clarification before application
- 8 fl oz volume may be limiting for larger onion plantings
Best for: Onion growers with small beds or pots who want a specifically onion-focused liquid and value the stated chelated micronutrient feature.
Not ideal for: New gardeners who want uncomplicated handling or unambiguous mixing directions, and large-scale growers who need a larger supply.
- Brand:Gardenera
- Product form:Liquid
- Liquid volume:8 fl oz
- Item weight:4 oz
- Specific use:Onions
- Mixing ratio:3:1:2
- pH:Approximately 1.69
- Number of items:1
Our verdict“Pick Gardenera for a small onion crop when micronutrient features matter and you are prepared to verify and follow the mixing guidance.”
Jobe’s Organics Granular Bone Meal Fertilizer, 4 lb
Jobe’s Organics Bone Meal stands apart from the liquid onion-specific choices by offering a granular, OMRI-listed source of phosphorus and calcium rather than a broad allium feeding formula. Its 2-14-0 analysis makes its role clear: it is a phosphorus-heavy amendment that can support root development, but it does not supply nitrogen or potash according to the listed analysis. That makes it a better fit as part of a planned soil-feeding program than as a one-bag answer to every onion nutrient need. Compared with Old Cobblers Farm Wicked Growth, which lists nitrogen, phosphate, potash, sulfur, calcium, boron, and zinc, Jobe’s is narrower but offers organic-gardening certification and granules designed to reduce dust. It calls for repeat applications every eight weeks or as needed, and a soil test is recommended before adding more phosphorus.
Pros:- OMRI listed for organic gardening
- 2-14-0 analysis provides a disclosed phosphorus-forward nutrient profile
- Granulated form reduces dust during application
- Suitable for vegetables, flowers, bulbs, and tubers
Cons:- Listed analysis contains no nitrogen or potash
- Repeat application may be needed every eight weeks or as needed
- A soil test is recommended before use to avoid unnecessary phosphorus
Best for: Organic gardeners building a soil-test-informed onion program who want a granular phosphorus and calcium source that can also be used around other crops.
Not ideal for: Growers seeking a complete allium fertilizer with listed nitrogen and potash, or anyone whose soil test does not call for additional phosphorus.
- Brand:Jobe’s Organics
- Weight:4 lb
- Form:Granules
- NPK ratio:2-14-0
- Certification:OMRI listed for organic gardening
- Application frequency:Every 8 weeks or as needed during the growing season
- Unit count:64 oz
- Pack quantity:1
Our verdict“Choose Jobe’s when an organic, phosphorus-focused granular amendment fits your soil plan, not when you need a complete onion fertilizer.”
Prevegenics Onion Fertilizer – 32 fl oz
Among the liquid options in this group, Prevegenics’ 32-ounce bottle is the practical choice for gardeners who want more concentrate on hand for an onion-focused routine. Its product details describe a blend of macronutrients and micronutrients, while the stated dilution—1 part fertilizer to 3 parts water—is simpler to follow than Gardenera’s less clearly explained 3:1:2 listing. The larger volume also separates it from the 8-ounce TPS Nutrients and Gardenera bottles, which are better matched to modest plantings. However, the available information does not give a specific NPK analysis, so the broad nutrient claim is harder to evaluate or compare against soil needs. It is also designated for onion, rather than a broad range of crops, so gardeners feeding a mixed vegetable plot may prefer an allium fertilizer with a wider stated target list.
Pros:- 32 fl oz volume offers more concentrate than the 8-ounce liquid options
- Described as providing both macronutrients and micronutrients
- Clear stated dilution ratio of 1 part fertilizer to 3 parts water
- Target species is listed as onion
Cons:- No specific NPK values are provided in the supplied product details
- Designed specifically for onions, limiting its stated fit for mixed-crop feeding
- Requires dilution before use
Best for: Gardeners with a substantial onion bed who want a larger liquid supply and a stated dilution ratio for repeated preparation.
Not ideal for: Growers who need a disclosed NPK analysis to match a soil test, or those seeking one fertilizer for a wide mix of non-onion crops.
- Manufacturer:Prevegenics LLC
- Item form:Liquid
- Liquid volume:32 fluid ounces
- Target species:Allium cepa
- Specific use:Plant growth
- Mixing ratio:1 part fertilizer to 3 parts water
- Number of packs:1
- Part number:OBF-32O
Our verdict“Choose Prevegenics for a larger onion planting if bottle volume and a stated dilution ratio matter more than a fully disclosed nutrient analysis.”
Old Cobblers Farm Wicked Growth Garlic and Onion Fertilizer, 20 lb
Old Cobblers Farm Wicked Growth has the broadest listed nutrient profile for an allium-focused granular feed here: it supplies nitrogen, phosphate, and potash, with sulfur, calcium, boron, and zinc also listed. That makes it more of a complete allium-specific choice than Jobe’s Organics Bone Meal, whose 2-14-0 analysis is concentrated on phosphorus and contains no listed potash. Wicked Growth also provides separate pre-planting and side-dressing rates, plus a stop-feeding window before harvest, giving established beds a defined application schedule. Those instructions require more attention than the simple dilution step on Prevegenics Onion Fertilizer, and the product data contain a significant packaging discrepancy: the title says 20 lb while item details say 5 lb. Buyers should confirm the actual package size before planning coverage.
Pros:- Targets a broad range of alliums, including onions, garlic, shallots, leeks, and chives
- Lists nitrogen, phosphate, potash, sulfur, calcium, boron, and zinc
- Provides both pre-planting and side-dressing application rates
- Includes guidance to stop feeding 2 to 3 weeks before harvest
Cons:- Product title lists 20 lb while item details list 5 lb, so package weight is unclear
- Application timing and rates require more attention than a simple diluted liquid feed
- Feeding should stop 2 to 3 weeks before harvest
Best for: Gardeners growing several alliums—such as onions, garlic, shallots, leeks, or chives—who want a granular fertilizer with listed primary and additional nutrients.
Not ideal for: Buyers who need an unambiguous package weight, prefer liquid feeding, or want a low-maintenance schedule without pre-planting and side-dressing steps.
- Brand:Old Cobblers Farm
- Model number:WG-5-10-10
- Form:Granules
- Weight:20 lb in title; 5 lb in item details
- Nutrient analysis:5% ammoniacal nitrogen, 10% phosphate, 10% potash
- Additional nutrients:3% sulfur, 2% calcium, boron, and zinc
- Target plants:Garlic, onions, shallots, leeks, and chives
- Application rate:1/2 to 1 cup per 10 sq ft before planting; 1/2 cup per 10 linear feet for side-dressing
- Harvest timing:Stop feeding 2 to 3 weeks before harvest
Our verdict“Choose Wicked Growth for a multi-allium bed and a granular nutrient blend, but confirm the package weight before planning your application.”
TPS Nutrients Liquid Onion Fertilizer, 32 fl oz
TPS Nutrients Liquid Onion Fertilizer is the more adaptable choice for gardeners who want to apply an allium-focused product with a watering can or sprayer. Its liquid form suits garden beds, raised beds, and containers, making it easier to work into small or mixed plantings than Wicked Growth Garlic and Onion Fertilizer, which is a granular blend intended for pre-plant use and side-dressing. The product is formulated to support roots, foliage, and bulb development, but the supplied details do not list its nutrient analysis or dilution rate. That makes application harder to plan precisely than Wicked Growth’s stated 5-10-10 formula and measured rates. I’d favor TPS for flexible application, but gardeners who want disclosed nutrient levels should choose a more transparent option.
Pros:- Formulated for onions and other alliums, including bulb-forming crops.
- Liquid format can be applied with a watering can or sprayer.
- Suitable for garden beds, raised beds, and containers.
Cons:- The supplied product details do not provide an NPK analysis.
- No dilution instructions are included in the supplied details, making application planning less precise than with Wicked Growth.
- The liquid format may require more frequent application than a granular fertilizer, depending on label directions.
Best for: Container gardeners and growers with mixed allium beds who prefer applying fertilizer through a watering can or sprayer.
Not ideal for: Gardeners who need a disclosed NPK analysis and clear dilution instructions to calculate a precise feeding schedule.
- Brand:TPS Nutrients
- Form:Liquid
- Volume:32 fl oz
- Application method:Watering can or sprayer
- Target plants:Onions and other alliums
- Suitable growing areas:Garden beds, raised beds, and containers
- Made in:USA
Our verdict“Choose this liquid option if you want flexible application across onion beds and containers, but skip it if you require disclosed nutrient levels and dilution guidance.”
Old Cobblers Farm Wicked Growth Garlic and Onion Fertilizer, Bulb Crop Plant Food for Onions, Shallots and Leeks
Wicked Growth Garlic and Onion Fertilizer earns this spot for growers who want a disclosed formula and specific application rates. Its 5-10-10 NPK, 3% sulfur, calcium, boron, and zinc give onion growers more information for matching fertilizer to a soil test than the TPS Nutrients 32 fl oz liquid, whose supplied details omit nutrient analysis and dilution directions. The granular product also covers several alliums, from onions to shallots and leeks, and can be applied before planting or as a side-dress. That precision comes with extra work: the listed rates need careful measuring, granules must stay off foliage and bulb shoulders, and the product calls for soil testing to reduce over-application risk. For growers who want a smaller bag and a clearly stated formula, this is more manageable than the 20 lb Wicked Growth version in the roundup.
Pros:- Discloses a 5-10-10 NPK ratio and 3% sulfur for more informed soil-test-based feeding.
- Includes calcium, boron, and zinc alongside its primary nutrients.
- Can be used pre-plant and as a side-dress during the season.
- Targets multiple alliums, including onions, garlic, shallots, leeks, and chives.
Cons:- Requires careful rate calculation and soil testing to limit over-application risk.
- Granules must be kept off foliage and bulb shoulders, adding handling steps.
- The granular format is less convenient than TPS Nutrients Liquid Onion Fertilizer for growers who prefer application with a watering can or sprayer.
Best for: Allium growers who use soil tests, want a clearly disclosed NPK and sulfur content, and need one fertilizer for onions, shallots, leeks, or garlic.
Not ideal for: Beginners who want a simple liquid application or gardeners unwilling to measure rates carefully and keep granules away from foliage and bulb shoulders.
- Form:Granular
- Weight:5 lbs
- NPK ratio:5-10-10
- Sulfur content:3%
- Calcium:2%
- Micronutrients:Boron and zinc
- Pre-plant application rate:1/2 to 1 cup per 10 sq ft
- Side-dress application rate:1/2 cup per 10 linear ft
Our verdict“Choose Wicked Growth if you want a clearly labeled granular formula for several alliums and can follow measured application rates carefully.”
How We Picked
I compared these seven options by crop fit, fertilizer format, package size, and likely ease of use. Onion-specific liquids earned attention for convenient measured feeding, while bone meal and larger granular blends were judged on their fit for bed preparation and wider coverage. I also looked at whether a product’s stated crop range could serve other alliums, which matters to gardeners growing shallots or leeks alongside onions.
The ranking favors options with a clear role and a practical fit for a common buyer, not products that simply come in the largest package. TPS Nutrients Liquid Onion Fertilizer, 8 fl oz takes the lead as a focused, small-scale option; the Jobe’s granular product ranks as a distinct soil-amendment alternative, and Old Cobblers Farm’s 20 lb bag moves up for larger plantings. The remaining liquids and broader bulb-crop products are useful alternatives, but their best fit depends more heavily on package needs and preferred application style.
| onion fertilizer | Brand | Form |
|---|---|---|
| TPS Nutrients Liquid Onion Fer | TPS Nutrients | Liquid |
| Gardenera Liquid Power Onion F | Gardenera | — |
| Jobe’s Organics Granular Bone | Jobe’s Organics | Granules |
| Prevegenics Onion Fertilizer | — | — |
| Old Cobblers Farm Wicked Growt | Old Cobblers Farm | Granules |
| TPS Nutrients Liquid Onion Fer | TPS Nutrients | Liquid |
| Old Cobblers Farm Wicked Growt | — | Granular |
Factors to Consider When Choosing Best Onion Fertilizers
Before choosing a bag or bottle, match the product to your soil, planting area, and feeding routine. These broader checks can help prevent overbuying or using a fertilizer that does not suit the stage of growth.
Match the fertilizer to your soil, not just the crop name
An onion label does not replace a basic soil assessment. A soil test can show whether your bed needs additional nutrients or whether it already has enough, helping you avoid applying a product by habit. Bone meal, such as the Jobe’s option here, is a granular amendment with a different role from a liquid feed, so do not assume the two are interchangeable. Check the product label for its nutrient analysis and directions, then compare that information with your soil results. If the soil is already nutrient-rich, a smaller or more targeted application may be preferable to adding a broad fertilizer mix. This step matters more than choosing a product solely because it says “onion” on the package.
Choose a format that fits your routine
Liquids can be straightforward to measure and apply during the growing season, but they may require more frequent attention depending on their label directions. Granules are often easier to work into a bed before planting or spread across a larger area, though they still need correct placement and watering as directed. A busy gardener may favor a format that matches existing watering or bed-preparation habits rather than adding a new task. Avoid guessing at dilution rates or application frequency; follow the product’s instructions because concentrated liquids and dry amendments are handled differently. If you grow in containers, check that the product directions suit container use before applying it.
Buy for the planting area you actually have
Package size should reflect the number of plants and how often you expect to feed them. A small bottle like TPS Nutrients’ 8 fl oz size can be a practical starting point for a modest garden, while a 32 fl oz bottle or 20 lb bag may make more sense for repeated use across larger beds. Bigger packages can reduce the need to restock, but they also take more storage space and can leave unused product if your planting plans change. Compare the label’s coverage and application rate rather than judging by volume or weight alone. Keep any remaining fertilizer stored as the label directs, away from moisture and children or pets.
Check whether you want an onion-only or allium-wide product
Some products in this lineup focus on onions, while Old Cobblers Farm also offers a blend described for garlic and onions and a bulb-crop product intended for onions, shallots, and leeks. A wider crop range can be useful when one garden bed contains several alliums, but it is not automatically a better fit for a single-crop grower. Check that every crop you plan to feed appears on the label and that the application directions suit each one. Do not assume all alliums have identical fertilizer needs or timing. If you grow only onions, a broader label may add little value unless its format or package size suits your routine.
Pay for convenience or coverage—not claims alone
A larger package or specialized label does not by itself show that a fertilizer will produce better bulbs. Pay more attention to the nutrient analysis, application directions, package coverage, and whether the format fits your garden. A compact liquid may be easier for a first-time grower to measure, while a bulk granular option can be more practical for a long row or several beds. Be cautious about applying extra fertilizer in hopes of speeding growth; excess nutrients can create problems and may not improve the harvest. When comparing products, favor clear directions and a suitable dose over broad performance promises.
Frequently Asked Questions
Should I choose the 8 fl oz or 32 fl oz TPS Nutrients bottle?
I would choose the 8 fl oz bottle for a small onion patch, a first purchase, or a gardener who wants to limit leftover concentrate. The 32 fl oz size is a better fit if you plan to feed a larger area or use the product repeatedly according to its label. Compare the stated dilution and coverage, since bottle size alone does not tell you how many applications you will get. Store either size as directed after opening. If you are unsure how much you will use, starting smaller can reduce waste.
Can I use bone meal instead of a liquid onion fertilizer?
Not automatically: bone meal and liquid fertilizers differ in nutrient composition, release pattern, and application method. Jobe’s Organics Bone Meal may suit gardeners preparing or amending soil, while a liquid product is intended for measured feeding according to its own directions. Check the nutrient analysis on both labels and use a soil test to identify what your bed needs. Combining products without checking their nutrient contributions can lead to unnecessary applications. Choose the format that matches the soil condition and timing, rather than treating one as a direct substitute for the other.
Is a garlic-and-onion fertilizer suitable for shallots or leeks too?
Do not infer crop approval from a product name alone. Old Cobblers Farm lists a bulb-crop plant food for onions, shallots, and leeks, while its garlic-and-onion blend has a different stated crop range. Read the specific package directions to confirm the crops covered and their application instructions. If the label does not list a crop, contact the manufacturer before using it there. This is especially useful when one bed contains several alliums with different planting dates.
Should I use onion fertilizer before planting or during the growing season?
The right timing depends on the product’s label, its format, and your soil’s nutrient needs. Granular amendments are often worked into soil as part of bed preparation, whereas liquid products may be applied during growth when their directions call for it. Do not apply both approaches on the same schedule without checking their nutrient contributions. A soil test can help determine whether pre-plant feeding is needed at all. Follow the label’s rate and timing rather than increasing applications to try to force faster growth.
Which option makes sense for a large onion bed?
For a broad planting, I would compare the coverage and application rate of Old Cobblers Farm’s 20 lb fertilizer with the 32 fl oz TPS Nutrients liquid before choosing. The granular bag may be easier to distribute across a bed, while the larger liquid bottle may suit a grower who prefers measured feeding. The better fit depends on your application routine, storage space, and the product’s directions—not simply its package size. Check whether the product is intended for your planting method and soil conditions. If you grow onions alongside other alliums, the stated crop range may also affect the choice.
Conclusion
Best overall: I would start with TPS Nutrients Liquid Onion Fertilizer, 8 fl oz, for a focused onion-specific liquid in a manageable size. Best value for larger plantings: Old Cobblers Farm Wicked Growth Garlic and Onion Fertilizer, 20 lb, is the bulk-format pick, provided you can use and store the full bag. Best for beginners: the smaller TPS bottle offers a more controlled starting point than a large package, as long as you follow its dilution directions. Best for soil amendment: Jobe’s Organics Granular Bone Meal is the distinct choice for gardeners who prefer a dry product and have confirmed their soil needs it. For growers feeding shallots or leeks too, I would check Old Cobblers Farm’s bulb-crop plant food label; choose Gardenera or Prevegenics if their bottle size and directions better match your routine. Match the final pick to your soil, planting scale, and application preference.
Columbus Day / Indigenous Peoples' Day Picks
long weekend sales
As an affiliate, we earn on qualifying purchases.
