By Prem Nand, Clinical Dietitian - Nutritionist, NZRD

If you want healthier soil, stronger plants, and bigger harvests, making your own homemade natural fertilizer is one of the most effective things you can do. The best part? You can create a nutrient-rich fertilizer using simple ingredients you already have at home: eggshells, banana skins, horse manure tea, and comfrey.
In this guide, you’ll learn how to combine these ingredients to make an organic fertilizer that feeds your plants with calcium, nitrogen, potassium, phosphorus, magnesium, trace minerals, and beneficial microbes.

🥚 Why Eggshells Are Great for Fertilizer Crushed and baked eggshells provide calcium carbonate, which helps prevent blossom-end rot, supports strong cell walls, and builds overall plant resilience. When turned into a calcium extract, eggshells release calcium more quickly and are easier for plants to absorb.


🍌 Why Banana Skins Belong in Your Garden Fertilizer Banana skins are naturally rich in potassium and magnesium. These minerals support:
• Flower production
• Fruit development
• Strong stems
• Overall plant health
When blended into a puree, banana skins break down even faster, delivering nutrients more efficiently.


🐎 The Power of Aged Horse Manure Tea Aged horse manure that has been sitting in water for months becomes a microbial powerhouse. It provides:
• Gentle nitrogen
• Beneficial bacteria
• Humic substances
• Microbial activity that improves soil health
This creates a strong base for your homemade natural fertilizer.


🌱 Comfrey: The Ultimate Nutrient Accumulator Comfrey leaves contain:
• Nitrogen
• Potassium
• Calcium
• Iron
• Manganese
• Growth-promoting plant hormones
Adding comfrey supercharges your fertilizer with fast-acting and slow-release nutrients.


🧪 How to Make Your Homemade Natural Fertilizer (Step-by-Step)
Ingredients You’ll Need • 135 g baked and crushed eggshells
• 2–3 litres aged horse manure tea
• 2 litres banana-skin water
• 1 jug of banana skins soaked for several days
• 2–3 handfuls comfrey leaves
• Rainwater (or tap water left overnight)
• 10 L bucket with lid


🔥 Step 1: Prepare the Eggshell Calcium Extract To release calcium quickly:
1. Place the crushed eggshells in a jar.
2. Cover with white vinegar.
3. Allow it to fizz for 24 hours.
4. Strain and keep the liquid.
5. Add leftover solids to your compost later.
If you don’t want to use vinegar, you can simply add the crushed shells directly to the bucket. They will release calcium slowly over time.


🌀 Step 2: Prepare the Banana Skin Liquid Blend the banana skins with their soaking water. Puree until smooth. This speeds up nutrient availability and makes the potassium easier for plants to absorb.


🪣 Step 3: Combine Everything in a 10-Litre Bucket Fill the bucket with 5 litres of water. Add:
• Horse manure tea
• The blended banana liquid
• Comfrey leaves
• The calcium extract (or crushed shells)
Top up with water to make a full 10 litres. Stir well. Cover loosely with a lid or breathable cloth.


⏳ Step 4: Let Your Fertilizer Brew Allow the mixture to sit for 7–14 days.
Stir every 1–2 days. The mixture should smell earthy, not rotten.
During this time:
• Microbes multiply
• Nutrients release from the banana skins and comfrey
• Calcium disperses
• Organic acids form
• The brew becomes a balanced liquid fertilizer


🌼 Step 5: Strain and Use Your Fertilizer After brewing, strain the liquid into a clean container. Keep the solids and add them to your compost or directly under mulch for slow-release feeding.


💧 How to Use Your Homemade Natural Fertilizer This fertilizer is strong, so dilute before using.

Dilution Rate:
• 1 cup (250 ml) fertilizer per 2 litres of water, or
• 1 litre fertilizer per 8–10 litres of water

Water the base of plants every 2–4 weeks.
Perfect for:
• Tomatoes
• Peppers
• Cucumbers
• Pumpkins
• Corn
• Fruit trees
• Heavy-feeding flowers


This recipe provides a complete spectrum of nutrients:
✔️ Nitrogen
(from manure + comfrey)
✔️ Potassium
(from banana skins + comfrey)
✔️ Calcium
(from eggshell extract)
✔️ Magnesium + Phosphorus
(from banana skins + manure)
✔️ Trace minerals
(from comfrey + eggshells)
✔️ Beneficial microbes
(from manure tea)
✔️ Plant hormones
(from comfrey)
The result is a fertilizer that boosts plant growth, flowering, fruiting, and soil health—all without chemicals.

Adding Selenium Sources for NZ Soil

Because NZ soils are notoriously low in selenium, here are much better options:

⭐ Seaweed / Kelp Meal (best natural option)

Naturally contains selenium + iodine + boron + micronutrients.

⭐ Organic Selenium Granules

“Selcote Ultra” is often used in NZ farming.

⭐ Selenium-enriched compost

Almost all quality compost blends include trace selenium.

⭐ Sheep manure (from farms that use selenium drenches)

Sheep drench/mineral blocks contain selenium → appears in manure.

🌿 Final Thoughts 

Making your own homemade natural fertilizer is an easy, cost-effective way to build living soil, support sustainable gardening, and give your plants a nutrient-dense boost. With simple kitchen scraps and natural ingredients, you can create a powerful organic fertilizer that rivals expensive store-bought products.