Fish may not be the first thing that comes to mind when you think of plant food — but it’s one of the most powerful natural fertilizers available.
For centuries, gardeners have used fish scraps and emulsions to grow lush vegetables, vibrant flowers, and strong roots. Fish fertilizer is packed with essential nutrients and feeds both your plants and the microbes in your soil.
But what if you don’t want to deal with the mess or odor?
Good news: you don’t need a full fish or smelly concoctions. There’s an easy, low-odor way to make fish fertilizer — using kitchen leftovers or store-bought scraps — and in this article, you’ll learn exactly how.
Why Fish Fertilizer Works So Well
Fish and fish waste contain a wide array of nutrients vital for plant growth:
- Nitrogen – encourages leafy green growth
- Phosphorus – promotes root development and flowering
- Potassium – supports overall plant health
- Calcium and magnesium – strengthen cell walls
- Micronutrients – such as iron, sulfur, and zinc
- Amino acids – support microbial and root health
This combination makes fish fertilizer especially useful for vegetables, herbs, fruit trees, and flowering plants.
It feeds plants quickly, enhances soil fertility, and encourages beneficial microbial activity that lasts for weeks.
Who Should Use Fish Fertilizer?
Fish fertilizer is ideal for:
- Organic gardeners looking for chemical-free nutrition
- Those growing heavy-feeding crops like tomatoes or squash
- Gardeners who want fast results with minimal effort
- Anyone seeking to recycle kitchen scraps responsibly
It’s also safe for pets, pollinators, and kids — when made and used properly.
3 Easy Ways to Make Fish Fertilizer at Home
🐟 Method 1: Fish Scrap Soak (Low-Odor Liquid Fertilizer)
This is the easiest and cleanest DIY method.
You’ll need:
- Leftover fish parts (head, bones, skin, fins — raw or cooked, but unsalted)
- 1 tbsp brown sugar or molasses
- 2–3 liters of clean water
- A bucket with a loose lid or breathable cover
Instructions:
- Place fish scraps in the bucket
- Add sugar or molasses (feeds the microbes and controls odor)
- Add water to cover completely
- Stir, then loosely cover
- Let ferment outdoors in shade for 7–14 days
- Stir once daily to prevent anaerobic smell
How to use:
- Dilute 1 part fish fertilizer with 10 parts water
- Water at plant base every 2–3 weeks
Tip: This method avoids strong odor if kept outdoors and stirred regularly.
🧴 Method 2: Fish Emulsion with Blender (Faster Breakdown)
This is a quick version for immediate use.
You’ll need:
- 1 cup fish scraps or canned fish in water (unsalted)
- 1 banana peel (optional for potassium)
- 1 tbsp used coffee grounds (adds nitrogen)
- 2 cups water
- A blender
Instructions:
- Blend all ingredients until smooth
- Use immediately as soil drench (not on leaves)
- Store leftovers in refrigerator for up to 2 days
How to use:
- Apply ½ cup to soil around each plant
- Use every 2–3 weeks during growing season
Perfect for container gardens or raised beds.
🪴 Method 3: Bury Fish Scraps Under Plants (Old-School Method)
This is the most traditional method, with no processing required.
Instructions:
- Dig a hole 6–8 inches deep near your plant
- Place a small piece of raw fish or bones
- Cover with soil
- Plant on top or nearby
Use for:
- Tomatoes, squash, corn, melons, peppers
- Newly planted fruit trees or shrubs
Note: Bury deep enough to avoid pest attraction. Avoid salty, fried, or seasoned fish.
Best Plants for Fish Fertilizer
This fertilizer supports both leafy and fruiting plants. Ideal for:
- Tomatoes, cucumbers, peppers, eggplants
- Leafy greens: kale, lettuce, spinach
- Squash, zucchini, pumpkins
- Beans, corn, and peas
- Roses, hibiscus, flowering annuals
- Fruit trees: citrus, figs, apples
- Herbs: basil, parsley, mint
Avoid using it directly on succulents or root crops (like carrots or radishes) unless heavily diluted.
How Often Should You Use It?
- Liquid fish soak: every 2–3 weeks
- Fish emulsion: every 2 weeks during peak growth
- Burying scraps: once per plant at transplanting or early season
Too much can cause excess nitrogen — leading to large leaves but fewer flowers.
Always observe plant response and adjust frequency if needed.
Tips to Avoid Odor and Pests
- Use brown sugar or molasses in fermentation to reduce smell
- Keep covered but breathable to allow gases to escape
- Always bury scraps deep enough to prevent animals from digging
- Avoid leaving any fish residue exposed to air
Clean tools and containers thoroughly after use.
FAQs
Will fish fertilizer attract flies or animals?
Only if misused. Bury scraps deep or ferment in a sealed container. Liquid forms are generally safe if diluted and poured directly into soil.
Can I use fish fertilizer on indoor plants?
Yes — but only the blended and diluted versions. Avoid raw scraps indoors.
Is fish fertilizer safe for all plants?
It’s excellent for flowering and fruiting plants. Use less often for succulents or light feeders.
What if I don’t eat fish — can I still use it?
Yes — ask a fishmonger for scraps or use canned fish in water (unsalted). Some gardeners also use fish-based pet food in small amounts.
How long does fish fertilizer last?
Fermented fish soak lasts about 2–3 weeks unrefrigerated. Use blended forms within 48 hours, or freeze for later.
Final Thoughts
Fish fertilizer is one of the oldest and most powerful natural plant boosters — and now, it’s easier than ever to make at home.
With a little preparation, you can recycle scraps, avoid waste, and feed your plants something they truly love.
Stronger stems. Bigger blooms. More fruit. Richer soil.