Comparison: Best Making Fish Fertilizer (Updated | Dec 1st)

Check the NPK ratio to match your plant’s nutrient needs, and verify if the product is OMRI listed for organic gardening. Look for additional ingredients like kelp or seaweed that can boost micronutrients. Also consider the concentration; higher‑strength formulas may require more dilution but give you more applications per container.

Most products use a 5‑1‑1 ratio, which provides a strong nitrogen boost for leafy growth, while others like Neptune’s Harvest offer 2‑4‑1 or 2‑3‑1 ratios for more balanced feeding of fruits and flowers. Choose a lower‑nitrogen formula if you’re focusing on blooms or fruiting, and a higher‑nitrogen blend for rapid foliage development.

Traditional fish emulsions, such as the Central Garden Brands and Alaska Fish Emulsion, have a characteristic fishy smell that many gardeners find strong. Neptune’s Harvest and GS Plant Foods use cold‑process methods that retain oils but reduce odor, while the 1‑gallon organic fish emulsion explicitly notes a pungent aroma as a sign of authenticity. If scent is a concern, opt for deodorized or low‑odor options.

The 1‑gallon containers, like the Central Garden Brands and GS Plant Foods liquid fish & kelp fertilizer, provide the lowest cost per ounce and are ideal for extensive beds or multiple applications. Neptune’s Harvest 36‑ounce bottles also give good bulk pricing, but they lack the kelp component that adds extra micronutrients. Consider how many gallons you’ll need and compare price‑per‑gallon to decide.

OMRI listing is important if you practice certified organic gardening; Alaska Fish Fertilizer and GS Plant Foods both carry this certification. Additionally, the GS Plant Foods product is reviewed by the Organic Materials Review Institute, which adds a layer of trust for organic growers. Certifications ensure the fertilizer meets strict organic standards and won’t jeopardize organic certification.

All listed products are water‑soluble and can be applied as a soil drench, foliar spray, or through drip irrigation after proper dilution. Some, like Fertilome, provide specific mixing ratios for trees versus garden plants, while others, such as the API Leaf Zone, are formulated for aquarium plants and may not be suitable for soil use. Follow the label instructions for each brand to avoid over‑application and potential plant burn.

Indoor growers often prefer low‑odor, gentle formulas; the Alaska Fish Emulsion (deodorized with natural wintergreen) and the 1‑gallon organic fish emulsion are good choices because they provide balanced nutrients without strong smells. Central Garden Brands also states it “does not burn,” making it safe for sensitive indoor foliage. Always dilute to the recommended strength to prevent root stress.

Yes, GS Plant Foods combines fish hydrolysate with kelp, which adds trace minerals and promotes beneficial microbial activity. Neptune’s Harvest includes seaweed and retains natural fish proteins and oils that improve soil structure and nutrient uptake. These added components can enhance long‑term soil fertility beyond the basic NPK values.