Companion Plants
How to make fish emulsion for plants turns your kitchen sink into a nutrient goldmine—it’s simpler than you think, using just a few ingredients and a little patience to transform scraps into a powerful liquid fertilizer that outperforms store-bought options. I've been using homemade fish emulsion for three seasons now, and my tomatoes and peppers have never looked healthier or produced more.
The beauty of this process is that you control the quality and avoid the synthetic additives found in commercial fertilizers. All you need are a few pounds of fresh fish scraps (heads, bones, and all), water, and a container to brew in.
The smell is strong—think ocean breeze meets compost pile—but the results are worth it: deep green leaves, bushier growth, and flowers that seem to bloom overnight. Plus, it's free or nearly free compared to buying pre-made emulsions.
You'll end up with a dark, rich liquid that smells like the sea and feeds your plants with nitrogen, phosphorus, and potassium—plus micronutrients they crave. Dilute it properly, and you'll see stronger stems, more abundant blooms, and vegetables that taste like they've been grown with extra love.
The best part? This isn't just for gardeners with big plots; even container plants thrive with a little fish emulsion love.
Fair warning: the brewing process takes about 2-3 weeks, but you can speed it up with a little heat or agitation. And yes, it does attract flies—so keep it covered or in a shaded spot.
Once you've made your first batch, you'll never go back to buying fertilizers again. Here's how to get started without the guesswork.
📚 In This Guide
- What you need
- Instructions
- Tips and common mistakes
- Wrapping up and next steps
What you need
- ● Fresh fish scraps: 1–2 lbs (preferably bony, oily fish like salmon, sardines, or mackerel for maximum nutrients). Avoid farmed fish with antibiotics if possible.
- ● Water: 1 gallon (distilled or dechlorinated tap water works best).
- ● Non-metallic container: A 1–2 gallon glass jar, food-grade plastic bucket, or ceramic crock (no aluminum or reactive metals!).
- ● Breathable cover: A cheesecloth, coffee filter, or lid with small holes to allow gases to escape while keeping pests out.
- ● Wooden or plastic spoon/stirrer: Avoid metal to prevent chemical reactions.
- ● Glove: A pair of nitrile or rubber gloves to handle fish scraps (trust us, it gets smelly!).
- ○ Strainer or cheesecloth: For filtering out solids after fermentation (optional but helpful).
- ● Small funnel: To transfer liquid without spills.
- ○ pH strips (optional): To test acidity (ideal range: 6.0–7.0 for plants).
- ○ Food-grade calcium carbonate (optional): 1 tsp per gallon to neutralize odor if needed.
Step-by-Step instructions for crafting fish emulsion fertilizer
Here's how to create a rich, organic fertilizer using simple kitchen scraps and a little patience.
Gather and Prepare Fresh Fish Scraps
Start with 2-3 pounds of fresh fish scraps—heads, bones, and trimmings work best. Rinse thoroughly to remove any salt or preservatives, then chop into ½-inch pieces for faster decomposition. I like to use a clean knife or kitchen shears for this step, as it speeds up the process significantly.
Place the scraps in a 5-gallon bucket or large container with a tight-fitting lid. The goal is to minimize odor and prevent pests. If you're using particularly strong-smelling scraps, like anchovies or sardines, consider adding a splash of water to help contain the smell during the initial breakdown phase.
Add Water and Stir Daily
Fill the container with enough water to completely submerge the fish scraps, leaving about 2 inches of space at the top. Stir the mixture daily to keep it aerobic—this prevents foul odors and speeds up decomposition. You'll notice the water turn cloudy and develop a strong, fishy smell within the first 24-48 hours.
After about 3-5 days, the scraps will begin to break down into a thick, brownish liquid. This is your fish emulsion forming. If you see mold or a slimy film on top, stir it in—it’s part of the natural process. The mixture should smell pungent but not rotten; a sour or putrid odor means it’s time to discard and start fresh.
Strain and Dilute for Use
Once the scraps have fully decomposed—usually after about 7-10 days—strain the liquid through a fine mesh sieve or cheesecloth into a clean container. The leftover solids can be composted or buried in your garden as a nutrient boost. The strained liquid is your concentrated fish emulsion, but it’s too strong to use directly on plants—always dilute it first.
For most plants, mix 1 tablespoon of emulsion per gallon of water. For heavy feeders like tomatoes or peppers, you can double this to 2 tablespoons per gallon. Apply the diluted solution to the soil around plants, avoiding direct leaf contact to prevent burning. I prefer using it as a foliar spray for fruit trees, but always test a small area first to check for sensitivity.
Store and Use Your Fertilizer
Store the concentrated emulsion in a sealed container in a cool, dark place. It will keep for up to 6 months, though the potency fades over time. Label it clearly—fish emulsion has a distinctive smell, and you’ll want to avoid accidental spills or confusion with other garden liquids.
Use your fish emulsion every 2-4 weeks during the growing season for best results. It’s packed with nitrogen, phosphorus, and potassium, plus trace minerals that promote lush foliage and strong root development. For the most balanced approach, alternate it with a compost tea or seaweed extract to provide a wider range of nutrients.
Tips & tricks for perfect fish emulsion fertilizer
Real talk: turning fish scraps into liquid gold takes patience, but these little tricks will keep your process smooth and your garden thriving.
The Chop Factor: When you're prepping those 2-3 pounds of fresh fish scraps in Step 1, aim for ½-inch pieces—no smaller, no larger. Smaller pieces break down faster, but they can also create a slimy mess that's harder to strain later. Larger chunks take forever to decompose. Use kitchen shears for speed, but a sharp knife gives you better control over consistent sizing.
Oxygen is Your Best Friend: In Step 2, that daily stirring isn't just about mixing—it's about keeping your emulsion aerobic. The 24-48 hour cloudy phase is when good bacteria do their magic, breaking down the fish into nutrients. If you notice a thick scum forming on top after 3-5 days, don't skim it off! That's natural yeast and bacteria doing their job. Just stir it in and keep going.
Smell Test Matters: Trust your nose more than the clock. That pungent fish smell after 3-5 days is normal, but if it turns sour or putrid, you've gone too far. The 7-10 day decomposition window is flexible—some fish break down faster, others slower. When the scraps are completely mushy and the liquid is dark brown, that's your cue to strain. The solids should fall apart easily when pressed between your fingers.
Dilution Precision: When you're ready to use your emulsion in Step 3, measure carefully. That 1 tablespoon per gallon for most plants is the sweet spot—too much can burn roots. For heavy feeders like tomatoes, the 2 tablespoons per gallon gives them the nitrogen boost they crave. I keep a separate spray bottle labeled "fish emulsion" for foliar applications, filled with the diluted solution. It's amazing how quickly fruit trees respond when you spray the undersides of leaves every 2-4 weeks.
Pro Tips for Make Fish Emulsion For Plants
- Real talk: turning fish scraps into liquid gold takes patience, but these little tricks will keep your process smooth and your garden thriving.
- The Chop Factor: When you're prepping those 2-3 pounds of fresh fish scraps in Step 1, aim for ½-inch pieces—no smaller, no larger.
- Oxygen is Your Best Friend: In Step 2, that daily stirring isn't just about mixing—it's about keeping your emulsion aerobic.
Frequently asked questions
Got questions about making fish emulsion for your plants? You’re not alone!
Here are answers to the most common queries to help you get the most out of this nutrient-rich fertilizer.
Can I use any type of fish to make fish emulsion?
Not all fish work equally well. Opt for bony fish (like sardines, anchovies, or herring) for the best results—the bones contain calcium and phosphorus, which are great for plants. Avoid oily fish (like salmon or tuna) as they can spoil faster. When in doubt, stick to small, fresh, or frozen fish from the seafood section!
How long does homemade fish emulsion last?
Homemade fish emulsion typically lasts 1–2 months when stored properly in an airtight container in the fridge. For longer shelf life, freeze it in ice cube trays—just thaw before use. If it smells rotten or overly sour, toss it out to avoid harming your plants.
When is the best time to apply fish emulsion to plants?
Apply fish emulsion during the active growing season (spring and summer) when plants need a nutrient boost. For best absorption, use it in the evening or early morning to avoid burning leaves in direct sunlight. Dilute it first (1:10 ratio) and water the soil—not the foliage—to prevent salt buildup.
Is homemade fish emulsion cheaper than store-bought?
Yes! Homemade fish emulsion is far more cost-effective than commercial versions. A few dollars’ worth of fish can yield gallons of fertilizer, saving you money while giving you full control over ingredients. Plus, it’s chemical-free and packed with natural nutrients your plants will love.
What should I do if my fish emulsion smells bad or attracts pests?
If your emulsion smells strong or attracts flies, it’s likely fermenting too long. To fix it, add a splash of vinegar or lemon juice (1 tbsp per quart) to balance the pH and reduce odors. For pests, store it in a sealed container with a tight lid, and keep it in the fridge. If the smell is overpowering or moldy, discard it and start fresh.
Wrapping up and next steps
Making your own fish emulsion for plants is a rewarding way to give your garden a nutrient boost without breaking the bank! With just a few simple ingredients and a little patience, you’ve unlocked a powerful, organic fertilizer that’ll help your plants thrive.
Now that you’re equipped with the know-how, it’s time to get growing—start small, experiment with your plants, and watch them flourish!
🌱 Next step: Try it on a small batch of plants and observe the results. Adjust ratios or ingredients based on what works best for your garden! Happy gardening! 🌿