Fish Emulsion for Cannabis: What It Is and How to Use It
Fish emulsion is a liquid organic fertilizer made from heat- and acid-processed fish waste, and growers use it mainly as a nitrogen source for cannabis. Extension guides list typical analyses of about 4-1-1 to 5-2-2. It is mixed into water before feeding, and its strong smell is the drawback most often mentioned.
What Is Fish Emulsion?
Colorado State Extension describes fish emulsions as soluble liquid fertilizers made of fish waste that has been heat and acid processed, and says they are infamous for their smell (Colorado State). Iowa State lists fish emulsion as a nitrogen source with about 5% sulfur (Iowa State). Both are general garden guides rather than cannabis studies. Fish emulsion is one of many outdoor fertilizer options.
What Is the NPK of Fish Emulsion?
Iowa State lists fish emulsion at 4-1-1 and Colorado State at 5-2-2, with release over 1 to 4 months. Fish meal is a different product. Iowa State lists it at 5-3-3 and Colorado State at 10-6-2 (Iowa State, Colorado State). Nitrogen is the main nutrient in all of them, which matters if your plants show signs of nitrogen deficiency.
Sources: Iowa State University Extension and Colorado State University Extension (typical analyses, general garden guidance). Analyses vary by product.
Data for this chart:
| Product | N | P | K | Source |
|---|---|---|---|---|
| Fish emulsion | 4 | 1 | 1 | Iowa State |
| Fish emulsion | 5 | 2 | 2 | Colorado State |
| Hydrolyzed liquid fish | 4 | 2 | 2 | Colorado State |
| Fish meal | 5 | 3 | 3 | Iowa State |
Is Fish Emulsion the Same as Fish Hydrolysate?
No. Colorado State says enzymatically digested hydrolyzed liquid fish uses enzymes instead of heat and acid. This keeps more proteins, enzymes, vitamins and micronutrients than emulsions do. It lists a typical analysis of 4-2-2 and notes these products cost more than emulsions (Colorado State).
How Do Growers Use Fish Emulsion on Cannabis?
Colorado State, in a general garden guide, suggests mixing about 6 tablespoons of fish emulsion per gallon of water, and 5 tablespoons per gallon for hydrolyzed fish (Colorado State). Iowa State lists 2, 1 or 1 oz per 1,000 sq ft for low, medium or adequate fertility soil and advises a conservative first application, since more can be added but too much is hard to undo (Iowa State). Feeding it in soil fits into a soil feeding schedule. Mix rates differ by brand. Check the product label and local rules.
Sources
The sources below give general garden or container guidance rather than studying cannabis. Their findings are reported as results for those settings.
- Colorado State University Extension: Organic Fertilizers
- Iowa State University Extension: Selecting and Using Organic Fertilizers
General growing information only: Kind Seed Co gathered these fish emulsion notes from the extension guides above.
FAQ
Does fish emulsion smell bad?
Yes, that is its best-known drawback. Colorado State Extension calls fish emulsions infamous for their foul smell and lists the smell of some products as the main con. Enzymatically digested fish products are made a different way, but the guide does not say whether they smell less.
What is the difference between fish emulsion and fish meal?
Fish emulsion is a liquid made from heat- and acid-processed fish waste, while fish meal is ground, heat-dried fish waste that is tilled into soil. Iowa State lists emulsion at 4-1-1 and meal at 5-3-3. Colorado State lists fish meal higher, at 10-6-2.
How often can you use fish emulsion?
The extension guides give amounts, not a schedule. Colorado State lists release over 1 to 4 months and a mix rate of about 6 tablespoons per gallon. Iowa State advises starting conservatively, watching how plants respond and adding more only if needed.
Is fish emulsion organic?
It is an organic fertilizer, meaning it comes from natural sources. Colorado State notes that this is not the same as approval for the USDA National Organic Program, and that groups such as OMRI review brand-name products. Check a product's listing if certified organic status matters to you.
