How to make liquid fertilizer at home? – 9 easy recipes

Gardening isn’t just about planting seeds—it’s about nurturing life. While a seed starting mix gives your seedlings a strong launch, they quickly need more nutrients. That’s where liquid fertilizer shines. It’s fast-absorbing, eco-friendly, and costs pennies.

Best of all, you can make liquid fertilizer at home using kitchen scraps and weeds! I’ve used these for years in my garden, and they’re game-changers.

Why I Skip Store-Bought?

Homemade fertilizer reduces waste, saves money, and avoids synthetic chemicals. Plus, I control what goes into my plants.

Whether you’re nurturing a seed starting mix or feeding mature crops, how to make liquid fertilizer at home is a skill every gardener should master.

The Science of DIY Liquid Fertilizers

Liquid fertilizers work through rapid nutrient mineralization. Water-soluble elements (K, Ca, Mg) leach into solution, while fermentation breaks down complex compounds into plant-available forms.

Essential Components:

1. NPK Ratios:
   • N (Nitrogen) for leafy growth
   • P (Phosphorus) for roots/blooms
   • K (Potassium) for disease resistance
2. Secondary Nutrients: Calcium, Magnesium, Sulfur
3. Microbes: Lactobacillus from fermentation aids nutrient uptake

How to Make Liquid Fertilizer

All homemade liquid organic fertilizer follows a simple process:

1. Soak ingredients in water.
2. Ferment for 1–4 weeks (stirring weekly).
3. Strain and dilute before use.

Recommended: Use rainwater or dechlorinated tap water—chlorine kills beneficial microbes!

Now, let’s dive into my favorite recipes + 3 bonus recipes.

9 Easy Homemade Liquid Fertilizers (+ Recipes)

1. Banana Peel Fertilizer

Why it works: Packed with potassium (K), phosphorus (P), and calcium—ideal for fruiting and flowering.

Recipe:

It may ferment slightly – that’s not a problem, it just smells.

1. Chop 3–4 banana peels + 1 tbsp eggshells (optional).
2. Soak in 1 quart of water for 2–3 days. Strain.
3. Add 1 tsp blackstrap molasses to feed microbes. (optional)

Dilution: 1:3 with water (e.g., 1 cup fertilizer + 3 cups water).

If you don’t dilute it:

• Excess potassium may accumulate, which can hinder the absorption of other nutrients (especially calcium and magnesium).
• In potted plants, this can lead to yellowing of the leaves or growth deformities with prolonged use.

Watering: Only around the roots, not on the leaves.
Frequency: Оnce every 10–14 days.
Best for: Flowering/fruiting plants like tomatoes, peppers, roses.

Tip: After straining the banana water, you can lightly bury the remaining peels in the soil (away from the stem) – they will decompose and provide slow-release nutrients.

2. Nettle Fertilizer

Why it works: Rich in nitrogen (N), iron, potassium (K), microelements, and magnesium. Great for young plants – stimulates leaf growth and strong stem development. The stinging nettle fertilizer is one of my favourites as well!

Recipe:

1. Fill a bucket ¾ full with fresh nettles (wear gloves!).
2. Cover with rainwater. Weight down with a stone.
3. Ferment 7-10 days (stir every 3 days; it will smell strong).
4. Strain when foamy.

Dilution: 1:10 (foliar) or 1:20 (soil) with water.
Bonus: Spray undiluted to deter aphids!

Watering: Only around the roots, not on the leaves.
Frequency: Оnce every 10–14 days.
Best for: Leafy greens (lettuce, kale), brassicas, seedlings.

Don’t boil – it’s fermented! Fermentation extracts the nutrients best; boiling destroys them.

3. Potato Water Fertilizer

Why it works: Rich in potassium, phosphorus, and micronutrients. Starchy water also leaches potassium and vitamin B6.

Recipe:

1. Option 1: Save water from boiling potatoes (without salt). Cool completely. Use immediately!
2. Option 2: Collect potato peels and soak them in 1 liter of water for 24-48 hours. Use it immediately after soaking.

• Boiling – this is safer, as it breaks down the starch and prevents rotting. It is good if you plan to store it for a few days.
• Without boiling – it’s riskier since it may sour or grow mold.

Dilution: None needed. Use straight.

Watering: Only around the roots.
Frequency: Оnce every 10 days.
Best for: Root vegetables (carrots, beets), herbs.

4. Rice Water Fertilizer

Why it works: Fermented rice water contains NPK, lactic acid, and beneficial bacteria. Lactobacillus prevents damping-off disease!

Recipe:

Option 1: Fresh (raw)

1. Rinse 1 cup of rice in 2 cups of water until cloudy.
2. Shake for 30 seconds to 1 minute.
3. Strain and use directly for watering.

Dilution: Use undiluted.

Option 2: Fermented (stronger)

1. Rinse 1 cup of rice in 2 cups of water, sit for 1–2 days at room temperature.
2. When it starts to smell slightly (fermentation), it’s ready.
3. Strain.

Dilution: 1:3 with water.

My recommendation:
• Always use unsalted and unsweetened water.
• Do not use water in which rice was cooked with spices, oil, or salt.
• Do not use if there is mold or a rotten smell – discard it.

Watering: Only around the roots, also you can spray leaves for pests.
Frequency: Оnce every week for watering and once every 10-14 days for spraying.
Best for: Seedlings, flowering/fruiting plants like tomatoes, peppers, cucumbers, herbs, orchids, houseplants.

5. Fish Emulsion (Fish Water)

Why it works: High in nitrogen (N) and trace minerals. Smelly but powerful!

Recipe:

1. Blend fish scraps (heads, guts) with equal parts water and 1/4 cup vinegar (optional)
2. Ferment 4–6 weeks in a sealed jar (burp weekly!).
3. Strain.

Vinegar preserves proteins (better than rancid emulsions).

Dilution: 1:1 with water.

My recommendation:
• Don’t use for orchids or plants that prefer poor, clean soil.
• Do not use if the water contains algae treatments, antibiotics, or other chemicals.
• After watering with fish tank water, avoid additional fertilizing for at least 1–2 weeks.

Frequency: Оnce every 2 weeks.
Best for: Heavy feeders like corn, squash, and cucumbers, herbs, flowering indoor plants, and evergreen houseplants.

6. Eggshell & Vinegar Calcium Tonic

Why it works: Eggshells add calcium; vinegar makes it soluble. Vinegar (acetic acid) breaks down calcium carbonate and converts it into calcium acetate, which plants can absorb immediately.

Recipe:

1. Put the crushed eggshells into a jar (fill about 1/3 of it).
2. Pour in vinegar until the shells are fully covered.
3. Foam will start to form – this is normal (a reaction between calcium carbonate and vinegar).
4. Leave the jar open (or covered with gauze) for 3–5 days, stirring gently once a day.
5. When the shells stop “fizzing” and are almost fully dissolved, the liquid is ready.
6. Strain and store in a sealed bottle in a cool place.

Dilution: 1 tablespoon per gallon of water.

My recommendation:
• Do not use frequently – excess calcium can disrupt soil pH.
• Do not water acid-loving plants (azaleas, orchids, rhododendrons).
• Always dilute – this concentrated mixture is strong!

Frequency: Оnce per month if needed.
Best for: Preventing blossom-end rot in tomatoes/peppers, cucumbers. Flowering plants – strengthen stems and buds.

7. Seaweed

Why it works: Rich in microelements (iron, zinc, copper). Contain growth hormones. Increase plant resistance to stress, diseases, and drought. Stimulate root formation.

Recipe:

1. Rinse 2 cups of fresh seaweed (remove sand).
2. Soak in 1 gallon of water for 3-4 days.
3. Strain.

Dilution: 1:3 with water

My recommendation:
• Don’t overuse – small amounts are enough, as this is a stimulant, not a primary fertilizer.
• If collecting seaweed from the beach – rinse thoroughly to remove salt!
• Don’t combine directly with strong nitrogen fertilizers – it may block their effect.

Frequency: Оnce per 2 weeks.
Best for: All plants (especially stressed transplants)

Contains cytokinins – reduces transplant shock in seed starting mix!

8. Wood ash

Why it works: Rich in potassium, calcium, magnesium, phosphorus, and no nitrogen.

Recipe:

Option 1: Dry ash (in the garden):

1. 1–2 handfuls per m² or 1 teaspoon per pot.
2. Sprinkled around the plants and lightly mixed into the soil.

Do not mix with nitrogen fertilizers (urea, manure-based fertilizers) – they neutralize each other.

Option 2: Liquid (ash tea):

1. Mix 1 cup of ash in 5 liters of water.
2. Stir and let sit for 24 hours.

My recommendation:
• Do not use ash from painted or varnished materials.

Watering: Only around the roots with 1 liter per plant.
Frequency: 1–2 times a month.
Best for: Sunflowers, geranium, tomatoes, peppers, beans, onions, garlic.

9. Compost tea

Why it works: High in balanced macro- and micronutrients. Acts as a probiotic for the soil. Stimulates growth and helps protect against diseases.

Recipe:

1. Add 1 cup of compost or manure to 3 liters of water.
2. Stir and cover with cheesecloth.
3. Let it sit for 24–48 hours (no longer).
4. Strain.

Dilution: 1:3 with water

My recommendation:
• Use within 2 days after straining – otherwise, it loses its effectiveness.
• Do not combine with mineral fertilizers on the same day.
• Do not use if it has a bad, rotten smell – this means the tea has fermented improperly.

Frequency: Once every 10–14 days.
Best for: General feeding, mature plants. Especially beneficial for rooting, seedlings, and depleted soils.

Don’t boil – heat kills the beneficial microorganisms.

How to Use Liquid Fertilizer

• Containers: Water every 2 weeks.
• Garden Beds: Apply monthly.
• Always water soil—not leaves (except nettle spray for pests).

When to Fertilize Seedlings

You can start fertilizing your plants when they show these signs:

Seedlings:

Apply 2 weeks after sprouting (dilute to half strength).

Strong roots & mature leaves:

• Roots are well-developed
• At least 4–6 true leaves (not just the first baby leaves!)

Settled into their “home”:

• 1 week after transplanting into individual pots
• OR given ample space in a larger container

Recovered from stress:

• Waited 5–7 days after transplanting or pruning
• Actively growing (no wilted or yellowing leaves)

What Fertilizer to Use (Stage-by-Stage Guide)

It’s important not to overload the same nutrients (especially nitrogen).

If you fertilize with multiple high-nitrogen sources at once, you can easily:

• Over-fertilize the plant (causing it to “burn” or produce excessive foliage at the expense of flowering)
• Damage the roots due to salt buildup

So fertilize as needed by the plant:

1. Early Growth Stage (Leaf & Stem Development):

Use HIGH-NITROGEN fertilizer

Examples:

• Nettle tea 
• Diluted fish emulsion 
  Why? Nitrogen fuels lush, green growth!

2. Flowering & Fruiting Stage (4-6 weeks later):

Switch to BALANCED or HIGH-POTASSIUM/PHOSPHORUS fertilizer

Examples:

• Banana peel tea (potassium booster)
• Comfrey tea (phosphorus powerhouse)

When it’s OK to Switch Fertilizers

1. When the plant’s growth stage changes – e.g., from vegetative growth to flowering, fruiting.

2. If you’re alternating between types (organic/mineral), as long as you don’t mix them at the same time.

3. If you’re observing the plant’s response, such as yellowing leaves (up nitrogen), weak growth, or lack of flowering (boost phosphorus & potassium).

6 Key Tips for Success

1. Water first. Moisten the soil before fertilizing to prevent root shock, OR BURN THEM.

2. Don’t pour over the leaves – some liquid fertilizers can leave residue.

3. Always dilute. Homemade fertilizers should look like weak tea.

4. Stop if stressed. Skip feeding if plants look wilted, heat-stressed, or diseased.

5. Test pH. Most homemade fertilizers are slightly acidic (pH 6–7). Adjust with wood ash if needed.

6. Store strained fertilizer in sealed jars in a cool, dark place for 3–6 months. Add 1 tbsp of molasses monthly to feed microbes.

Troubleshooting

• Yellow leaves? – Too much water or nitrogen imbalance.
• Flowers dropping? – Boost potassium (try banana tea ASAP!).
• Crispy leaf edges? – Over-fertilizing – Flush the soil with water.

Final Thoughts

Learning how to make a liquid fertilizer transforms your garden into a self-sustaining ecosystem. Start with banana peels or rice water—you’ll see thicker stems and brighter blooms in weeks.

Remember: gardening is about experimenting. Try these recipes, note what works, and share your results!

Frequently Asked Questions