Comparison: Best Fish Kelp Fertilizer (Updated | Dec 1st)
If you’re looking to give your garden a natural boost, fish kelp fertilizer is a powerhouse choice—but with so many options out there, how do you pick the best one? We’ve dug into the top contenders, comparing nutrient content, sustainability, ease of use, and real results in the soil.
Editor’s Choice
Best for a specific purpose
- Best for versatile organic boost: Omri Listed Fish & Kelp Fertilizer for Plants by GS Plant Foods (36oz) – Organic Fertilizer for Vegetables
- Best for soil microbe enhancer: GS Plant Foods Liquid Fish & Kelp Fertilizer (1 Gallon) – Organic Material Review Institute Listed Natural Plant Food for Home Gardens
- Best for fast-acting growth: Down To Earth All Natural Fertilizers Organic Liquid Fish & Kelp Concentrate – Plant Food for Vegetable Gardens and Flower Beds – Makes up to 32 Gallons 2-4-1
- Best for super-concentrated value: Organic Sea Kelp Fertilizer for Plants – Water-Soluble – Makes 50 Gallons – Kelp Meal Concentrate Plant Food – for Indoor Gardens
- Best for enzyme-rich cleankelp: Bloom City Organic Liquid Seaweed and Kelp Fertilizer Supplement
- Best for pure kelp nutrition: GS Plant Foods Liquid Kelp Fertilizer – Suitable for Organic Growing
- Best for bulk cleankelp blend: Bloom City Organic Liquid Seaweed and Kelp Fertilizer Supplement (128 oz) Concentrated Makes 750 Gallons
- Best for dual power formula: Indian River Organics Fish Plus Kelp Seaweed 128 oz. Concentrate
- Best for organic dual blend: Indian River Organics Fish & Kelp Blend Fertilizer – OMRI Listed Organic Fertilizer (36 oz) 1 Quart- Liquid Organic Fish and Kelp for Turf
- Best for soil structure booster: Kelp Bliss (5lbs) – Kelp Meal Organic Fertilizer for Plants
Product Comparison: Best Fish Kelp Fertilizer
Versatile Organic Boost
Omri Listed Fish & Kelp Fertilizer for Plants by GS Plant Foods (36oz) – Organic Fertilizer for Vegetables, Trees, Lawns, Shrubs, Flowers, Seeds & Plants – Hydrolyzed Fish and Seaweed Blend
GS Plant Foods
- OMRI ORGANIC LISTED FISH AND SEAWEED BLEND: GS Plant Foods all-natural liquid fish is a high quality organic product that gives excellent plant growth, rebuilds soil, and offers higher production yields. Kelp is often applied to any type of plants, trees, lawns, flowers, vegetables and seeds without concern for harmful runoff.
- OPTIMAL PLANT GROWTH & HEALTH AT HOME OR COMMERCIALLY: Used in low concentrations, liquid seaweed fertilizer acts as an efficacious growth promoter. GS Plant Foods fish seaweed fertilizer is used extensively on a commercial basis, as well as at home for gardeners as an organic soil conditioner. This fish fertilizer for vegetables will lead to healthier crop yields and general plant well being.
- EASY TO APPLY FOR NATURAL GREAT RESULTS: Apply liquid fish & kelp fertilizer to improve specific growth stages. For House Plants; use 1 tablespoon per gallon of water. Feed every two weeks and do not over water. For Outdoor Plants; Use 2 fl. Oz per gallon of water. Feed vegetables, flowers, trees and shrubs every 2-3 weeks. Apply until soil is saturated or as a foliar feed until leaves are wet, top and bottom. For Lawns; use 2 to 4 oz concentrate per gallon of water to cover 1,000 sq. ft.
- TRUSTED & RELIABLE: At GS Plant Foods, we understand that you are placing your trust in us to provide you with the highest quality products available. We have 100% confidence in the quality of our products and continuously strive to deliver the best customer experience. Our products are organic, easy to use, cost efficient, sustainable, and yield consistent & amazing results in your garden, no matter what you’re growing or what medium in which your plants are growing.
Soil Microbe Enhancer
GS Plant Foods Liquid Fish & Kelp Fertilizer (1 Gallon) – Organic Material Review Institute Listed Natural Plant Food for Home Gardens, Lawns, and Vegetables
GS Plant Foods
- 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.
Fast-Acting Growth
Down To Earth All Natural Fertilizers Organic Liquid Fish & Kelp Concentrate – Plant Food for Vegetable Gardens and Flower Beds – Makes up to 32 Gallons 2-4-1, 32 oz
Down To Earth All Natural Fertilizers
- Fast‑acting liquid formula: Perfect for foliar feed or soil drench applications, supporting quick absorption and growth stimulation.
- Stimulates overall plant vigor: High phosphorus aids flowering and fruiting, while nitrogen supports lush foliage and root development.
- Organic & soil‑friendly: Helps promote beneficial microbial activity and sustainable soil health due to its fish and kelp base
- Versatile application rates: For general garden use: ¼–½ cup per gallon of water; for containers: 2–4 Tbsp per gallon; for houseplants: 2 Tbsp per gallon, repeated every 2–4 weeks depending on growth stage
- Watch out for odor: While extremely effective, many users report a strong fish-like odor characteristic of fish emulsions—though it typically subsides quickly and doesn’t linger long indoors
Super-Concentrated Value
Organic Sea Kelp Fertilizer for Plants – Water-Soluble – Makes 50 Gallons – Kelp Meal Concentrate Plant Food – for Indoor Gardens, Hydroponics, Vegetables, Houseplants – Smart Grower – 2oz Bag
Smart Grower
- Organic Bio-Active Seaweed Harvested From Maine, USA – Smart Grower Sea-Kelp (Ascophyllum Nodosum) is boosted with rich source of naturally-derived organic polymers (fucoidan, alginate, and tannins) for maximum plant growth with NPK: 0-0-18 Soluble potash for enhanced nutrient uptake in plants
- 6X Stronger Super-Concentrated Powder – 2 oz pouch makes up to 50 gallons of highly water soluble powder mixable liquid kelp fertilizer for large and small indoor gardens, vegetable beds, and hydroponics and houseplants this is the best value on the market
- Healthier Bigger Plants Fast – Our Cold-Water Harvested in Maine Sea-Kelp plant food will boost your garden health and plant root strength because this organic kelp fertilizer supports natural plant stress resistance and maximum nutrient efficiency in all plant growing systems.
- Fast Results Proven and Trusted Organic Fertilizer – Thousands of farmers and gardeners use Smart Grower Sea-Kelp Meal Fertilizer to boost plant health for houseplants, vegetables, flowers, and hydroponic systems including seedlings and mature crops to get larger yields and bigger plants
- Easy-to-Use, and Compatible with Nutrients – Smart Grower Sea-Kelp fertilizer is fast-dissolving and easy to mix with water, simply apply every 1 to 2 weeks for stronger plants and bigger yields for all types of plants, gardens, and growing mediums
- Cruelty-Free, Organic, Small Batch, Non-GMO, Responsibly Harvested Sea-Kelp Plant Food All Smart Grower products are made in small batches to help restore the poisoned ecosystem of this planet for the optimal health of people, plants, and our planet
Enzyme-Rich CleanKelp
Bloom City Organic Liquid Seaweed and Kelp Fertilizer Supplement, Quart (32 oz) Concentrated Makes 180 Gallons
Bloom City
- 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
Pure Kelp Nutrition
GS Plant Foods Liquid Kelp Fertilizer – Suitable for Organic Growing, OMRI Listed Seaweed Concentrate for Lawns, Gardens & Soil – 1 Gallon (Makes Up To 800+ Gallons)
GS Plant Foods
- Organic Materials Review Institute Listed for Organic Use- Certified for use in organic gardening and farming, this natural seaweed extract fertilizer made from Ascophyllum Nodosum provides a balanced source of trace minerals and organic compounds that nourish plants and soil.
- Supports Soil Health & Nutrient Availability- Helps maintain favorable soil conditions and assists in nutrient uptake from the soil, contributing to healthy, productive plants.
- Suitable for All Types of Plants- Safe and effective for vegetables, fruits, ornamentals, lawns, trees, and shrubs—used by home gardeners and commercial growers as part of a regular fertility program.
- Simple, Flexible Application- Mix 2 ounces of concentrate per gallon of water and apply to soil or foliage with a sprayer, watering can, or hose-end sprayer. One gallon of solution treats up to 1,000 sq. ft.
- Trusted Quality from GS Plant Foods- We take pride in producing sustainable, high-quality organic fertilizers that are easy to use and compatible with any growing system. Consistent performance backed by a satisfaction commitment.
Bulk CleanKelp Blend
Bloom City Organic Liquid Seaweed and Kelp Fertilizer Supplement (128 oz) Concentrated Makes 750 Gallons
Bloom City
- 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
Dual Power Formula
Indian River Organics Fish Plus Kelp Seaweed 128 oz. Concentrate
Indian River Organics
- ORGANIC FISH AND SEAWEED FERTILIZER: Now our all-natural high quality fish fertilizer is combined with North Atlantic kelp to produce a plant nutrient source that is beyond compare. Your plants get all the benefits of a natural liquid fish fertilizer PLUS all the additional benefits of seaweed in one easy to use liquid product. Plants receiving both fish and seaweed fertilizer out-perform in every category, they are much healthier and more resistant to heat, drought, and cold.
- FISH IS PACKED WITH AMINO ACIDS AND MICRO NUTRIENTS: Our liquid fish fertilizer is an industry leader and produces amazing results in fruits, vegetables, plants, and lawns. It provides much more than just N-P-K (Nitrogen, Phosphorus and Potassium) found in synthetic fertilizers. Our organic liquid fish fertilizer provides a comprehensive mix of amino acids & micro nutrients and minerals all in a usable form perfectly suited for maximum efficiency of uptake for your plants.
- SEAWEED IS AN AMAZING PLANT SUPPLEMENT: We add North Atlantic kelp that is pure and free of contaminants. It is manufactured using our proprietary digestion and refinement process that breaks down complex polysaccharides into smaller, lower molecular weight particles and novel compounds. These new compounds are not present in the original ascophyllum nodosum biomass and are now in a bio- available form and some have been modified making them water soluble allowing for immediate plant benefit.
- EASY TO APPLY FOR GREAT RESULTS: For Lawn: Mix 2 oz in 1 gallon of water, spray to cover 500 square feet. Fruits & Vegetables: Mix 4 oz in 1 gallon of water, spray to drench, including underside of leaves. Flowers & Plants: Mix 3 oz in 1 gallon of water, spray to drench, including underside of leaves. Citrus & Other Trees: Mix 4 oz in 1 gallon of water, spray to drench, including underside of leaves. Seedlings: Mix 4 oz in 1 gallon of water.
- TRUSTED & RELIABLE: At Indian River Organics, we understand that you are placing your trust in us to provide you with the highest quality products available. We have 100% confidence in the quality of our products and continuously strive to deliver the best customer experience possible. Our products are organic, easy to use, cost efficient, sustainable, and yield consistent & amazing results in your garden, no matter what you’re growing.
Organic Dual Blend
Indian River Organics Fish & Kelp Blend Fertilizer – OMRI Listed Organic Fertilizer (36 oz) 1 Quart- Liquid Organic Fish and Kelp for Turf, Flowers, Shrubs, Plants, Fruits & Vegetables
Indian River Organics
- ORGANIC FISH AND SEAWEED FERTILIZER: Now our all-natural high quality fish fertilizer is combined with North Atlantic kelp to produce a plant nutrient source that is beyond compare. Your plants get all the benefits of a natural liquid fish fertilizer PLUS all the additional benefits of seaweed in one easy to use liquid product. Plants receiving both fish and seaweed fertilizer out-perform in every category, they are much healthier and more resistant to heat, drought, and cold.
- FISH IS PACKED WITH AMINO ACIDS AND MICRO NUTRIENTS: Our liquid fish fertilizer is an industry leader and produces amazing results in fruits, vegetables, plants, and lawns. It provides much more than just N-P-K (Nitrogen, Phosphorus and Potassium) found in synthetic fertilizers. Our organic liquid fish fertilizer provides a comprehensive mix of amino acids & micro nutrients and minerals all in a usable form perfectly suited for maximum efficiency of uptake for your plants.
- SEAWEED IS AN AMAZING PLANT SUPPLEMENT: We add North Atlantic kelp that is pure and free of contaminants. It is manufactured using our proprietary digestion and refinement process that breaks down complex polysaccharides into smaller, lower molecular weight particles and novel compounds. These new compounds are not present in the original ascophyllum nodosum biomass and are now in a bio- available form and some have been modified making them water soluble allowing for immediate plant benefit.
- EASY TO APPLY FOR GREAT RESULTS: For Lawn: Mix 2 oz in 1 gallon of water, spray to cover 500 square feet. Fruits & Vegetables: Mix 4 oz in 1 gallon of water, spray to drench, including underside of leaves. Flowers & Plants: Mix 3 oz in 1 gallon of water, spray to drench, including underside of leaves. Citrus & Other Trees: Mix 4 oz in 1 gallon of water, spray to drench, including underside of leaves. Seedlings: Mix 4 oz in 1 gallon of water.
- TRUSTED & RELIABLE: At Indian River Organics, we understand that you are placing your trust in us to provide you with the highest quality products available. We have 100% confidence in the quality of our products and continuously strive to deliver the best customer experience possible. Our products are organic, easy to use, cost efficient, sustainable, and yield consistent & amazing results in your garden, no matter what you’re growing.
Soil Structure Booster
Kelp Bliss (5lbs) – Kelp Meal Organic Fertilizer for Plants, Garden Soil, Flowers, Vegetables, & Lawns – Organic Kelp Fertilizer & Soil Amendment – 100% Natural Plant Food Rich in Vitamins & Nutrients
plantonix
- 100% Natural Kelp Meal Fertilizer – Kelp Bliss is a 100% natural garden fertilizer and soil amendment for plants that’s been sustainably harvested from sea kelp fresh from the ocean. Kelp meal fertilizer provides essential minerals, vitamins, and trace elements that improve nutrient uptake and encourage soil fertility in indoor plants and outdoor plants.
- Highly Renewable Plant Fertilizer – Kelp fertilizer is a natural source of essential nutrients like potassium, nitrogen, and phosphorus, providing a balanced boost of nutrition for indoor and outdoor gardens. Unlike other garden fertilizers, kelp meal fertilizer is made with no synthetic ingredients or additives. Plus, kelp meal is highly renewable, making it a great alternative to bone meal for plants.
- Improves Nutrient Absorption – Kelp meal is a perfect fertilizer for vegetables gardens, flower beds, lawns, orchids, indoor house plants, and as a soil amendment. Using kelp for plants helps maintain soil pH, keeping it within an optimal range for most plants. This makes it easier for plants to absorb vital nutrients, leading to improved nutrient uptake and efficiency.
- Excellent Water Retention – The organic matter in kelp meal improves the soil’s water-holding capacity, building drought tolerance and helping plants stay hydrated during dry periods. Using kelp meal for plants helps reduce watering frequency, so you can conserve more water and contribute to more sustainable gardening practices.
- Improves Soil Structure & Fertility – Using kelp fertilizer for plants adds valuable organic material to the soil, improving soil fertility and supporting beneficial microbes. Over time, these soil microbes enhance nutrient availability and improve soil conditions for better overall plant mass and crop yields.
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 fish‑kelp fertilizer?
Check if the product is OMRI‑listed, which guarantees it meets organic standards. Look at the concentration and recommended dilution rates to see how much product you’ll need for your garden size. Also consider the form—liquid concentrates are quick to apply, while powdered kelp offers a larger volume per purchase.
How do liquid fish‑kelp blends compare to pure kelp powders?
Liquid blends, like GS Plant Foods’ 1‑gallon concentrate, combine fish hydrolysate and seaweed for a balanced source of nitrogen, amino acids, and trace minerals, delivering fast foliar feeding. Pure kelp powders, such as Smart Grower’s 50‑gallon mix, provide high soluble potash (0‑0‑18) and are ideal for large‑scale or hydroponic setups where you want a low‑odor, long‑lasting supply.
Is there a noticeable odor difference between products?
Fish‑based fertilizers often have a mild fishy smell, especially with higher concentrations; Down To Earth notes this odor fades quickly after application. Pure kelp products and kelp‑only concentrates, like Bloom City’s Clean Kelp, are virtually odorless, making them better for indoor or indoor‑garden use.
Which product gives the best value for large gardens?
Smart Grower’s 6‑oz pouch makes up to 50 gallons of liquid kelp, offering a low cost per gallon for extensive beds. Indian River Organics’ 128‑oz fish‑plus‑kelp concentrate also covers large areas, but you’ll need to account for the higher price of the fish component. Compare the total dilution amount needed per square foot to determine the most economical choice.
Can I use the same fertilizer for both vegetables and lawns?
Yes, many of the listed products are multi‑purpose. GS Plant Foods’ liquid fish & kelp works on vegetables, lawns, and ornamental plants when mixed at 2 oz per gallon. Bloom City’s Clean Kelp is also safe for lawns and garden beds, allowing a single product to cover diverse planting zones.
How often should I apply fish‑kelp fertilizer for optimal growth?
Most manufacturers recommend feeding every 2–4 weeks, adjusting for plant stage: weekly for fast‑growing seedlings, and every 3 weeks for mature perennials. Liquid concentrates are typically applied as a foliar spray or soil drench, while powdered kelp is mixed into watering solutions and applied less frequently.
What are the key benefits of adding fish hydrolysate to kelp fertilizer?
Fish hydrolysate supplies readily available nitrogen and a spectrum of amino acids that boost foliage development and root health. Combined with kelp’s hormones and trace minerals, the blend improves soil microbial activity, leading to better nutrient uptake and increased stress tolerance for plants.