Comparison: Best Using Fish Fertilizer On Seedlings (Updated | Dec 1st)
If you’re growing seedlings, you might be wondering: can fish fertilizer give your tiny greens the boost they need? We’ve tested popular fish-based fertilizers on delicate seedlings to see which ones deliver strong growth without burning tender roots. From fast results to organic benefits, we’ll break down the top contenders so you can choose wisely. Let’s dive into what really works.
- Best for vitamin boost: CENTRAL GARDEN BRANDS 100099247 Fish Emul Fertilizer
- Best for omri certified blend: Alaska Fish Fertilizer OMRI Listed 5-1-1
- Best for deep green formula: Fertilome (10612) Fish Emulsion Fertilizer 5-1-1 (32 oz)
- Best for seaweed color enhancer: Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1 (36 Ounce)
- Best for wintergreen deodorized: Alaska Fish Emulsion Fertilizer 5-1-1 Concentrate 1 Gallon (Packaging may vary)
- Best for compact color boost: Neptune’s Harvest Fish & Seaweed Fertilizer 2-3-1
- Best for sustainable fish power: 1 Gallon Organic Fish Emulsion Fertilizer for Plants – Ideal Liquid Fish Fertilizer for Plants
- Best for kelp-infused soil: GS Plant Foods Liquid Fish & Kelp Fertilizer (1 Gallon) – Organic Material Review Institute Listed Natural Plant Food for Home Gardens
- Best for seedling root vitalizer: FoxFarm Bush Doctor Wholly Mackerel Fish Fertilizer
- Best for odorless protein rich: Neptune’s Harvest Fish Fertilizer 2-4-1
Product Comparison: Best Using Fish Fertilizer On Seedlings
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 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
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 (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
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 & 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
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.
FoxFarm Bush Doctor Wholly Mackerel Fish Fertilizer, Fx14113 – Liquid Plant Nutrient for Seedlings, Transplants, and Vegetative Growth – NPK 3-1-0 (Pint)
- SEEDLING & TRANSPLANT VITALIZER: This fish plant food promotes root strength, making it perfect for nurturing young seedlings & transplanted plants. Its fast-acting formula ensures plants receive rapid nutrition, helping them establish robust foliage
- EFFECTIVE ROOT DRENCH APPLICATION: This fish fertilizer for plants is for root drench applications, allowing nutrient absorption through the roots. It ensures deeper nutrient penetration, enhancing plant resilience, during early growth stages
- ESSENTIAL GROWTH INGREDIENTS: Made with fish protein hydrolysate, molasses, and kelp, this fish emulsion fertilizer provides a mix of nutrients. Fish protein provides essential amino acids, molasses gives soil microbes, and kelp supports plane health
- EASY MIX FOR THRIVING PLANTS: Using fish plant fertilizer is a breeze, simply mix 1 tablespoon per gallon of fresh water and drench the soil thoroughly. For optimal results, apply every other week throughout the vegetative cycle until early fruiting
- TRUSTED FOXFARM QUALITY: From a brand known for sustainable and effective gardening solutions, Our fish hydrolysate fertilizer is a high-quality option for feeding your plants. Trust FoxFarm for products that support lively gardens and vibrant plants
Neptune’s Harvest Fish Fertilizer 2-4-1, 36 Ounce
- Neptune’s Harvest is an organic fertilizer made from fresh north Atlantic fish
- It is made by a unique cold process that protects the vitamins, amino acids, enzymes and growth hormones
- It also contains all the micro and macro nutrients naturally found in fish
- Unlike fish emulsions, Neptune’s Harvest retains the fish proteins and oils and has no unpleasant odor
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 factors should I look for when choosing a fish fertilizer for seedlings?
Focus on the NPK ratio, organic certification, and concentration level. A lower nitrogen ratio (2‑3‑1 or 2‑4‑1) encourages balanced growth without burning tender seedlings, while OMRI‑listed products ensure compliance with organic standards. Also consider the size of the container; a gallon‑size concentrate is more economical for larger batches, whereas quart‑size bottles are handy for small indoor setups.
How does the NPK ratio influence seedling development, and which ratio is most suitable?
Seedlings benefit from a modest nitrogen level to avoid excessive leaf growth that can weaken stems; ratios like 2‑3‑1 (Neptune’s Harvest 2‑3‑1) or 2‑4‑1 (Neptune’s Harvest 2‑4‑1) provide just enough nitrogen while supplying ample phosphorus and potassium for root and flower development. The classic 5‑1‑1 formulas (Central Garden Brands, Alaska 5‑1‑1, Fertilome) deliver higher nitrogen, which is better for established plants but can be too strong for very young seedlings.
Which product gives the best value for a larger garden or multiple seedling trays?
The 1‑gallon Alaska Fish Emulsion 5‑1‑1 (B002RH0B26) and the 1‑gallon GS Plant Foods Liquid Fish & Kelp (B00BBLMXVQ) both provide high volumes at a lower per‑gallon cost, making them cost‑effective for extensive use. The Alaska concentrate also includes a natural wintergreen deodorizer, which can be a bonus for indoor growers who want less odor.
How do odor and formulation differences affect indoor seedling use?
Products like FoxFarm Wholly Mackerel and the Alaska Fish Emulsion are deodorized, reducing the typical fishy smell that can be unpleasant in indoor environments. In contrast, the 1‑gallon Organic Fish Emulsion (B09FZTPQJL) openly advertises its strong fish odor, which may be acceptable in a garage or greenhouse but less ideal for a home office.
Is it important to choose an OMRI‑listed fish fertilizer for organic gardening?
Yes, OMRI‑listed fertilizers such as Alaska Fish Fertilizer 5‑1‑1 and GS Plant Foods Liquid Fish & Kelp are certified for use in certified organic production, giving you confidence that the product meets strict organic standards. While non‑listed products still work, they may not be allowed in official organic certification programs.
What are the pros and cons of liquid versus concentrate fish fertilizers for seedlings?
Liquid ready‑to‑use formulas like Neptune’s Harvest 2‑3‑1 (18 oz) simplify mixing and reduce the risk of over‑concentration, which is helpful for beginners. Concentrates such as the 1‑gallon Alaska 5‑1‑1 let you stretch the product further and adjust strength for different growth stages, but they require careful dilution to avoid seedling burn.
Which fertilizer best supports beneficial soil microorganisms for healthy seedlings?
GS Plant Foods Liquid Fish & Kelp combines fish hydrolysate with seaweed, delivering both macro nutrients and trace minerals that feed soil microbes. Neptune’s Harvest also claims to stimulate microorganisms, but the added kelp in the GS formula gives an extra boost to microbial diversity and nutrient uptake.
What is the recommended application method and frequency for feeding seedlings with fish fertilizer?
Mix 1 tablespoon of a 5‑1‑1 concentrate per gallon of water for a gentle root drench, applying every 2 weeks during the seedling stage. For lighter 2‑3‑1 liquids, use 1 teaspoon per gallon as a foliar spray or soil drench, repeating every 10‑14 days to maintain steady growth without overwhelming young roots.