Comparison: Best Fish Oil Fertilizer For Plants (Updated | Dec 1st)

The most effective fish fertilizers contain a blend of fish emulsion, salmon oil, and natural omega‑3 fatty acids, which supply both macro‑nutrients and amino acids. Look for products that also list additional vitamins, enzymes, and trace minerals, as these support soil microbiology and plant health. Certifications such as OMRI indicate the formula meets organic standards.

Neptune’s Harvest and Bloom City formulations typically use a 2‑4‑1 ratio, emphasizing phosphorus for root and flower development, while some general‑purpose fish emulsions have a more balanced profile without a specific N‑P‑K label. The GS Plant Foods liquid combines fish hydrolysate with kelp, offering a broader spectrum of micronutrients rather than a strict N‑P‑K ratio. Choose a ratio that matches the growth stage of your plants—higher phosphorus for blooming, higher nitrogen for leafy growth.

Traditional fish emulsions can have a strong marine smell, but cold‑processed formulas like Neptune’s Harvest retain nutrients while reducing odor. Bloom City’s salmon‑based fertilizer is noted for a noticeable fish scent, whereas the GS Plant Foods liquid fish & kelp blend is formulated to be low‑odor. If scent is a priority for indoor gardening, opt for low‑odor, cold‑processed options.

Concentrated liquids such as the GS Plant Foods 1‑gallon bottle require dilution (typically 2 oz per gallon of water) and can be applied as a foliar spray or soil drench every 2–4 weeks. Smaller 8‑oz bottles like the Fish Emulsion Fertilizer are ready‑to‑use for quick top‑dressing, while larger quart‑size emulsions (e.g., Central Garden Brands) are suited for bulk soil incorporation. Always follow the manufacturer’s recommended ounces per gallon to avoid over‑fertilizing.

Products listed with OMRI certification, such as Alaska Fish Fertilizer and Just Scentsational Bare Ground Solutions, are verified for use in certified organic gardens, which can be important for growers seeking compliance. Certified options often undergo stricter sourcing and processing standards, potentially offering higher purity and fewer synthetic additives. While they may carry a premium price, the assurance of organic integrity can add value for environmentally conscious gardeners.

Bloom City’s 115‑oz Alaska Fish Fertilizer and the GS Plant Foods 1‑gallon liquid provide a high volume of product at a lower cost per ounce, making them economical for extensive beds or lawns. Neptune’s Harvest 36‑oz bottle also offers a good balance of price and potency, especially for growers who prefer the 2‑4‑1 ratio. Compare the listed price per ounce and factor in the recommended application rate to determine true value.

Sustainably sourced ingredients, such as Bloom City’s use of Alaskan salmon and GS Plant Foods’ responsibly harvested North Atlantic seaweed, reduce environmental impact. Look for statements about traceable sourcing, low‑by‑catch practices, and manufacturing in the USA, which often indicates tighter quality control. Choosing products with clear sustainability claims supports marine ecosystems while providing effective plant nutrition.

Most fish emulsions, including Central Garden Brands and Bloom City, are formulated for both indoor and outdoor use, but indoor growers should prioritize low‑odor, diluted applications to avoid strong smells. Outdoor applications can tolerate higher concentrations and are ideal for soil amendment before planting. Always check the label for any plant‑type restrictions, such as suitability for vegetables versus ornamental flowers.