Comparison: Best Seaweed Fish Emulsion Fertilizer (Updated | Dec 1st)
If you’re looking to give your garden a natural boost, you’ve probably heard about seaweed fish emulsion fertilizers. But with so many options out there, how do you know which one’s truly the best? We’ve dug into the bottles, analyzed the ingredients, and tested real results to bring you an honest comparison of the top contenders.
- Best for compact garden boost: Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1
- Best for larger value pack: Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1 (36 Ounce)
- Best for eco-friendly liquid: 1 Gallon Organic Fish Emulsion Fertilizer for Plants – Ideal Liquid Fish Fertilizer for Plants
- Best for omri certified strength: Alaska Fish Fertilizer OMRI Listed 5-1-1
- Best for vitamin-rich formula: CENTRAL GARDEN BRANDS 100099247 Fish Emul Fertilizer
- Best for wintergreen deodorized blend: Alaska Fish Emulsion Fertilizer 5-1-1 Concentrate 1 Gallon (Packaging may vary)
- Best for odorless growth boost: Neptune’s Harvest Fish Fertilizer 2-4-1
- Best for deep green formula: Fertilome (10612) Fish Emulsion Fertilizer 5-1-1 (32 oz)
- Best for versatile garden fertilizer: Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1 (Gallon)
- Best for kelp-infused nutrition: GS Plant Foods Liquid Fish & Kelp Fertilizer (1 Gallon) – Organic Material Review Institute Listed Natural Plant Food for Home Gardens
Product Comparison: Best Seaweed Fish Emulsion Fertilizer
Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1, 18 Ounce
- Grow a beautiful vegetable garden
- Flowers and foliage will be stronger and more colorful
- Blooms will be more plentiful, fragrant and longer lasting
- Easy to mix and apply by hand, sprayer, or drip line
Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1 (36 Ounce)
- Grow a beautiful vegetable garden
- Flowers and foliage will be stronger and more colorful
- Blooms will be more plentiful, fragrant and longer lasting
- Easy to mix and apply by hand, sprayer, or drip line
1 Gallon Organic Fish Emulsion Fertilizer for Plants – Ideal Liquid Fish Fertilizer for Plants, Flowers, Fruits & Vegetables, 2-3-1 NPK – Sustainably Sourced and Hydrolyzed for Steady Growth
- ORGANIC FISH EMULSION FERTILIZER – Our liquid fish fertilizer is made from sustainably sourced fish emulsion and we use up all the parts that would otherwise go to waste. Using an environmentally conscious method, ingredients are refined fresh and 100% cold pressed to help retain all of the nutrients, vitamins, and amino acids needed to grow healthy plants.
- GROW PLANTS NATURALLY – This wonderfully organic alternative to synthetic fertilizer contains a 2-3-1 NPK ratio perfect for light and frequent applications. Promotes steady, healthy plant development throughout the growing season.
- ENRICHES SOIL – Helps build a strong foundation for your organic garden to thrive on! Use as an effective soil drench to improve fertility, structure, and encourage the growth of beneficial microorganisms like fungi in your garden’s soil.
- PRODUCE MORE – Get the most out of your fertilizer and your garden! This organic garden fertilizer helps to increase crop yields and flower blooms. Gentle enough to use as a foliar spray makes this the perfect fish fertilizer for plants, flowers, and vegetables.
- SMELL THE DIFFERENCE – This fertilizer smells like fish because it’s made from fish! Crafted with high-quality concentrated and undiluted hydrolyzed fish emulsion each bottle gives off a pungent fishy aroma. When compared, we see it like this – if it doesn’t smell, then it’s not real fish!
Alaska Fish Fertilizer OMRI Listed 5-1-1, 115 oz
- Fish-based fertilizer for use in vegetable, fruit, and flower gardens
- Excellent for use on flowers, trees, and other plants
- OMRI listed
- For organic gardening
- Great for all indoor and outdoor plants
- NPK 5-1-1 fish emulsion fertilizer
- Fish has been used as a natural source of plant nutrients for centuries
- Easy to use, just mix with water
CENTRAL GARDEN BRANDS 100099247 Fish Emul Fertilizer, 1 Quart
- Promotes healthy plant growth with 11 vitamins
- Can be used on all indoor and outdoor plants
- 100-percent organic
- Stimulates microorganisms
- Does not burn
Alaska Fish Emulsion Fertilizer 5-1-1 Concentrate 1 Gallon (Packaging may vary)
- Will Not Burn
- Great for all plants
- Deodorized with Natural Wintergreen
- 5-1-1 fertilizer is an excellent source of organic plant nutrients
- Fish Fertilizer
Neptune’s Harvest Fish Fertilizer 2-4-1, Gallon
- An organic fertilizer made from fresh North Atlantic fish
- Made by a unique cold process that protects the vitamins, amino acids, enzymes and growth hormones
- Contains all the micro and macro nutrients naturally found in fish
- The nitrogen and other nutrients are chelated, so they are readily available for plants consumption
- The fish proteins and oils are retained and the fertilizer has no unpleasant odor
Fertilome (10612) Fish Emulsion Fertilizer 5-1-1 (32 oz)
- Develops deep green foliage, vigorous root systems and a solid plant structure
- Derived from fish soluble, can be used from indoor and outdoor. Can be used on plants and trees.
- Mixes with water and can be used by any convenient method of application. Shake well before use.
- 5-1-1 Fertilizer contains 5% Nitrogen, 1% Phosphate and 1% Soluble Potash.
- For plants mix 1-2 tbsp per 1 gal of water. For trees mix 4 tbsp per gal of water.
Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1 (Gallon)
- Grow a beautiful vegetable garden
- Flowers and foliage will be stronger and more colorful
- Blooms will be more plentiful, fragrant and longer lasting
- Easy to mix and apply by hand, sprayer, or drip line
GS Plant Foods Liquid Fish & Kelp Fertilizer (1 Gallon) – Organic Material Review Institute Listed Natural Plant Food for Home Gardens, Lawns, and Vegetables
- ORGANIC MATERIALS REVIEW INSTITUTE LISTED FOR TRUSTED GARDEN CARE Certified by OMRI for use in organic growing, GS Plant Foods Liquid Fish & Kelp Fertilizer delivers reliable, natural nutrition for vegetables, lawns, flowers, and shrubs.
- SEA-AND-SOIL BASED NUTRITION Made from North Atlantic seaweed (Ascophyllum nodosum) and fresh fish hydrolysate, this liquid concentrate provides essential nutrients and trace minerals that help support healthy soil and plant development.
- IMPROVES SOIL MICROBIOLOGY & NUTRIENT UPTAKE Supports a thriving soil ecosystem that promotes strong root systems and efficient nutrient absorption — the foundation for resilient, productive plants.
- EASY-TO-USE CONCENTRATE FOR ALL PLANTS Mix 2 oz per gallon of water and apply as a foliar spray or soil drench every 2–4 weeks. Safe for use on vegetables, fruits, ornamentals, turf, and houseplants.
- MADE IN THE USA – SUSTAINABLY PRODUCED Proudly produced by GS Plant Foods as a licensed fertilizer manufacturer. No synthetic chemicals, additives, or fillers — just natural ingredients formulated for healthy home gardens and hobby farms.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
Buying Guide
FAQs
What N‑PK ratio should I look for in a seaweed‑fish emulsion fertilizer?
Most gardeners prefer a 2‑3‑1 or 2‑4‑1 ratio for balanced vegetative and flowering growth, while a 5‑1‑1 ratio supplies extra nitrogen for rapid leaf development. Choose a ratio that matches your plant’s stage: lower nitrogen for blooming flowers and higher nitrogen for leafy vegetables. The products listed include 2‑3‑1 (Neptune’s Harvest), 2‑4‑1 (Neptune’s Harvest 2‑4‑1) and 5‑1‑1 (Alaska, Fertilome).
How important is organic certification when buying fish emulsion?
Organic certification, such as OMRI listing, assures the fertilizer meets strict standards for natural ingredients and no synthetic chemicals, which is crucial for certified organic gardens. Several options—Alaska Fish Fertilizer, GS Plant Foods, and Central Garden Brands—carry OMRI or OMRI‑equivalent status. If you’re growing food for personal consumption, choosing a certified product can also simplify compliance with local organic regulations.
Which product gives the best value per ounce?
Value depends on both price and concentration; larger containers like the 1‑gallon Neptune’s Harvest (2‑3‑1) or the 1‑gallon Alaska Fish Emulsion (5‑1‑1) typically offer the lowest cost per ounce. The 1‑gallon Organic Fish Emulsion (B09FZTPQJL) also provides a high nutrient density but may be priced higher due to its cold‑pressed processing. Compare the total ounces and the N‑PK strength to determine which gives the most nutrients for your budget.
Will the fertilizer have a strong fish odor, and does that matter?
Real fish emulsion naturally smells fishy; the Organic Fish Emulsion (B09FZTPQJL) advertises a pungent aroma as a sign of authenticity. Some brands, like Alaska Fish Emulsion, add wintergreen deodorizer to mask the smell, which can be preferable for indoor or patio use. Odor does not affect nutrient content, but a milder scent may be more comfortable for home gardeners.
Can I use these fertilizers on both indoor and outdoor plants?
Yes, most of the listed products are formulated for universal use, including indoor houseplants, outdoor vegetables, and ornamental flowers. Central Garden Brands and Alaska Fish Fertilizer specifically highlight suitability for indoor and outdoor applications. Just follow dilution instructions to avoid over‑fertilizing enclosed spaces.
What are the key differences between Neptune’s Harvest 18‑oz and 36‑oz bottles?
Both bottles share the same 2‑3‑1 N‑PK ratio and feature the same easy‑mix application methods, but the 36‑oz size offers a better price per ounce for gardeners who need larger volumes. The smaller 18‑oz can be a convenient trial size for new users or for limited‑space gardens. Functionally they are identical; the choice hinges on how much product you anticipate using.
How do seaweed ingredients enhance the performance of fish emulsion fertilizers?
Seaweed, such as Ascophyllum nodosum, supplies trace minerals, hormones, and natural growth stimulants that improve root development and stress tolerance. Products that combine fish emulsion with seaweed—Neptune’s Harvest, GS Plant Foods, and some Alaska blends—often promote more vigorous foliage and richer blooms compared with fish‑only formulas. The seaweed component also helps improve soil microbiology, supporting long‑term soil health.
What application methods are recommended for these liquid fertilizers?
All the listed fertilizers can be mixed with water and applied via hand watering, sprayer, or drip irrigation, making them versatile for different garden setups. For foliar feeding, dilute to the lower end of the recommended concentration (typically 1‑2 Tbsp per gallon) and spray on leaves during cooler parts of the day. Soil drenching with a slightly stronger mix encourages deep root uptake and is ideal for established vegetable beds.