Comparison: Best Fish Emulsion And Seaweed Fertilizer (Updated | Dec 1st)

Most fish emulsions have a 2-3-1 or 5-1-1 ratio, which provides a balanced supply of nitrogen for leaf growth, phosphorus for root development, and potassium for overall health. Choose 2-3-1 if you want a lighter, more frequent feeding schedule, or 5-1-1 if you need a stronger nitrogen boost for vigorous vegetative growth. Both ratios are suitable for vegetables, flowers, and fruiting plants, but the higher nitrogen version may be better for fast‑growing crops.

The 36‑ounce bottle offers roughly double the volume of the 18‑ounce size, which usually translates to a lower cost per ounce and fewer refills. If you garden regularly or have a large planting area, the larger container is more economical and reduces packaging waste. For occasional use or small indoor gardens, the 18‑ounce bottle is more convenient and easier to store.

Yes, an OMRI (Organic Materials Review Institute) listing guarantees the product meets organic certification standards, making it safe for certified organic gardens. Products like Alaska Fish Fertilizer and GS Plant Foods Liquid Fish & Kelp carry this designation, reassuring you that no prohibited synthetic chemicals are present. If you grow vegetables for market or prefer strict organic practices, prioritize OMRI‑listed options.

Alaska Fish Emulsion (5‑1‑1) is deodorized with natural wintergreen, reducing the typical fishy smell, which makes it suitable for indoor plants or close‑quarter gardening. In contrast, the 1‑gallon organic fish emulsion emphasizes a strong fish scent as a sign of authenticity. For indoor or greenhouse environments where odor matters, choose the wintergreen‑deodorized formula.

Seaweed, such as the Ascophyllum nodosum used in GS Plant Foods and Neptune’s Harvest blends, supplies trace minerals, hormones, and carbohydrates that stimulate root growth and improve stress tolerance. Adding seaweed to a fish emulsion enhances nutrient uptake and supports beneficial soil microbes, leading to stronger, more resilient plants. Products that combine fish and seaweed often yield more vibrant foliage and increased bloom production.

For a garden of 200–300 sq ft, a 1‑gallon (128 oz) container of fish emulsion provides enough concentrate for regular applications throughout the season without frequent repurchasing. The 1‑gallon Neptune’s Harvest or Alaska Fish Emulsion options are ideal, offering sufficient volume for soil drenches and foliar sprays. Smaller 8‑oz or 18‑oz bottles are better suited for container gardening or trial runs.

All listed products can be mixed with water and applied via hand watering, sprayer, or drip line, but some, like the Central Garden Brands 1‑quart fish emulsion, emphasize a gentle, non‑burning formula suitable for foliar feeding. The GS Plant Foods concentrate recommends a 2 oz per gallon dilution for both soil drench and foliar use every 2–4 weeks. Check the label for specific mixing ratios; products with higher nitrogen (5‑1‑1) may require more dilution to avoid leaf scorch.