Comparison: Best Seaweed Emulsion Fertilizer (Updated | Dec 1st)
If your garden’s been craving a natural boost, you’re not alone—and seaweed emulsion fertilizer might just be the secret weapon you’ve been missing. Packed with nutrients, growth hormones, and ocean-powered goodness, it’s no wonder gardeners everywhere are making the switch. But with so many options on the market, how do you know which one delivers real results?
- Best for compact garden boost: Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1
- Best for family-size growth: Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1 (36 Ounce)
- Best for seven-species surge: Bloom City Organic Liquid Seaweed and Kelp Fertilizer Supplement
- Best for mini seaweed power: Organic Liquid Seaweed and Kelp Fertilizer Supplement by Bloom City
- Best for bulk garden fuel: Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1 (Gallon)
- Best for pure fish nutrition: 1 Gallon Organic Fish Emulsion Fertilizer for Plants – Ideal Liquid Fish Fertilizer for Plants
- Best for omri certified boost: GS Plant Foods Liquid Fish & Kelp Fertilizer (1 Gallon) – Organic Material Review Institute Listed Natural Plant Food for Home Gardens
- Best for wintergreen safe feed: Alaska Fish Emulsion Fertilizer 5-1-1 Concentrate 1 Gallon (Packaging may vary)
- Best for versatile green builder: Fertilome (10612) Fish Emulsion Fertilizer 5-1-1 (32 oz)
Product Comparison: Best Seaweed 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
Bloom City Organic Liquid Seaweed and Kelp Fertilizer Supplement, Quart (32 oz) Concentrated Makes 180 Gallons
- FULLY ORGANIC SEAWEED AND KELP: A seven species blend of Ascophyllum Nodosum, Palmaria Palmata, Ecklonia Maxima, Laminaria Saccharina, Chlorella Vulgaris, Arthrospira Platensis, and Chondrus Crispus.
- EXTRACTED TO PROTECT NATURAL ENZYMES: Clean Kelp’s unique processing techniques give the cleanest possible kelp extract. Get all the benefits of natural kelp enzymes and hormones without the non-nutritious fibrous pulp that gives other kelps their thick, brackish appearance. You can see the difference.
- SIMPLE AND SAFE TO USE FOR ALL PLANTS: Add to every watering, it’s that easy. No risk of over application, plants love kelp. Clean Kelp aids in every stage of growth for root and stem health.
- FOR BOTH PLANTS AND LAWNS: Add Clean Kelp to all of your houseplants, vegetable garden, and your lawn for healthy green plants.
- FORMULATED AND MADE IN THE USA: Designed by botanists and plant chemists. Bloom City chooses only the highest quality ingredient sources and manufacturing methods to create the world’s best craft growing nutrient systems
Organic Liquid Seaweed and Kelp Fertilizer Supplement by Bloom City, (8 oz) Concentrated Makes 45 Gallons
- FULLY ORGANIC SEAWEED AND KELP: A seven species blend of Ascophyllum Nodosum, Palmaria Palmata, Ecklonia Maxima, Laminaria Saccharina, Chlorella Vulgaris, Arthrospira Platensis, and Chondrus Crispus.
- EXTRACTED TO PROTECT NATURAL ENZYMES: Clean Kelp’s unique processing techniques give the cleanest possible kelp extract. Get all the benefits of natural kelp enzymes and hormones without the non-nutritious fibrous pulp that gives other kelps their thick, brackish appearance. You can see the difference.
- SIMPLE AND SAFE TO USE FOR ALL PLANTS: Add to every watering, it’s that easy. No risk of over application, plants love kelp. Clean Kelp aids in every stage of growth for root and stem health.
- FOR BOTH PLANTS AND LAWNS: Add Clean Kelp to all of your houseplants, vegetable garden, and your lawn for healthy green plants.
- FORMULATED AND MADE IN THE USA: Designed by botanists and plant chemists. Bloom City chooses only the highest quality ingredient sources and manufacturing methods to create the world’s best craft growing nutrient systems
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
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!
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.
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
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.
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 should I look for when choosing a seaweed‑based fertilizer?
Check the NPK ratio to match your plant’s nutrient needs, and verify that the product lists the specific seaweed species used, as different blends provide varied hormone profiles. Look for organic certifications such as OMRI, which assure the formula meets organic standards. Also consider the concentration—concentrates like 5‑1‑1 need more dilution than ready‑to‑use 2‑3‑1 blends.
How do the Neptune’s Harvest 2‑3‑1 formulas compare to the Bloom City kelp supplements?
Neptune’s Harvest combines fish emulsion with seaweed for a balanced 2‑3‑1 NPK ratio, while Bloom City offers a pure seaweed extract with a broader spectrum of micronutrients but no nitrogen boost. The fish‑seaweed mix promotes vigorous foliage and blooms, whereas the kelp‑only product excels at enhancing root development and stress tolerance. Choose based on whether you need extra nitrogen or prefer a fully seaweed‑based boost.
Which product size gives the best value for a small home garden?
For a modest garden, the 18‑ounce Neptune’s Harvest bottle provides enough feed for several applications without excess waste, while the 8‑ounce Bloom City kelp is more economical if you only need occasional top‑ups. If you plan regular feeding, the 1‑gallon options (Neptune’s Harvest or GS Plant Foods) lower the cost per ounce and reduce packaging waste. Calculate the total ounces you’ll use per season to pick the most cost‑effective size.
Is the odor of fish emulsion a problem for indoor use?
Fish‑based fertilizers naturally have a fishy smell, which can be noticeable when mixing but usually dissipates after dilution. Products like Alaska Fish Emulsion are deodorized with natural wintergreen to lessen the scent, making them more suitable for indoor gardening. If odor is a major concern, a pure seaweed supplement such as Bloom City’s kelp fertilizer eliminates the issue entirely.
How should I apply these liquid fertilizers for optimal results?
Mix the recommended amount of concentrate with water and apply as a soil drench for root uptake, or use a fine mist sprayer for foliar feeding during the growing season. Neptune’s Harvest and GS Plant Foods work well with both drip irrigation and hand‑watering, while Bloom City’s kelp is designed for easy addition to every watering. Consistent, light applications every 2‑4 weeks generally outperform a single heavy feeding.
Do organic certifications matter when buying seaweed fertilizers?
Yes, certifications like OMRI confirm the product meets strict organic standards, ensuring no synthetic chemicals or prohibited additives are present. This is important for growers who maintain organic certification for their crops or who want to protect soil microbiology. Certified products also tend to have transparent ingredient sourcing, which can be a quality indicator.
How do the nutrient ratios differ among the listed products?
Neptune’s Harvest and the 1‑gallon organic fish emulsion both use a 2‑3‑1 ratio, providing a balanced blend of nitrogen, phosphorus, and potassium. Alaska Fish Emulsion offers a higher nitrogen 5‑1‑1 ratio for rapid leaf growth, while Bloom City’s kelp supplement does not list an NPK ratio because it focuses on micronutrients and growth hormones. Choose a ratio that aligns with your plant’s growth stage—higher nitrogen for vegetative growth, lower for flowering.
Are there any safety or plant compatibility concerns with these fertilizers?
All listed products are safe for vegetables, fruits, flowers, lawns, and houseplants when used according to label directions. However, over‑application of high‑nitrogen fish emulsions can cause leaf burn, especially on sensitive seedlings. It’s best to start with a weaker dilution and observe plant response before increasing the concentration.