🧮 Fertilizer Calculator - Urban Gardening

Fertilizer Calculator – Urban Garden Supplies

Calculate exactly how much fertilizer your garden needs

🧮 Fertilizer Amount Calculator

💡 How it works: Enter your garden details and fertilizer type to get precise measurements for healthy plant growth without waste.

Select Plant Type:

Garden Area Size:

Unit:

Fertilizer Type:

Application Frequency:

📚 Understanding NPK Numbers

NPK stands for Nitrogen (N), Phosphorus (P), and Potassium (K) – the three essential nutrients plants need.

Nitrogen – Leaf Growth

Promotes lush, green foliage and overall plant growth. Essential for leafy vegetables and lawns.

Best for: Lettuce, spinach, kale, lawns, herbs

Phosphorus – Root & Flower Development

Supports strong root systems, flower formation, and fruit production. Critical for blooming and fruiting.

Best for: Tomatoes, peppers, flowering plants, root vegetables

Potassium – Overall Health & Disease Resistance

Strengthens plant immunity, improves drought tolerance, and enhances fruit quality and flavor.

Best for: Fruiting vegetables, stressed plants, disease-prone areas

📖 Reading NPK Numbers: A bag labeled “10-10-10” contains 10% nitrogen, 10% phosphorus, and 10% potassium. The remaining 70% is filler material that helps distribute nutrients evenly.

Recommended NPK Ratios by Plant Type

Plant Type	Recommended NPK	Why
Leafy Greens	20-10-10 or 3-1-2	High nitrogen for leaf production
Tomatoes/Peppers	5-10-10 or 1-2-2	Lower nitrogen, higher P & K for fruiting
Root Vegetables	5-10-10 or 2-3-3	Phosphorus for root development
Flowering Plants	15-30-15 or 1-2-1	High phosphorus for blooms
Herbs	5-5-5 or organic compost	Low feeding needs, balanced growth
Lawns	20-5-10 or 4-1-2	High nitrogen for dense green growth

💡 Fertilizing Tips & Best Practices

⏰ Timing Matters

Best time: Apply in morning or evening when temperatures are cooler. Never fertilize during midday heat.

Season: Feed most heavily during active growing season (spring-summer).

💧 Water Before & After

Water plants 24 hours before fertilizing to prevent root burn. Water again immediately after applying granular fertilizer to activate nutrients.

📏 Less is More

Over-fertilizing causes more problems than under-fertilizing. Start with half the recommended amount and increase if needed.

🌱 Young vs Mature

Seedlings: Use 1/4 strength liquid fertilizer
Young plants: 1/2 strength
Mature: Full strength

🍂 Fall Feeding

Stop nitrogen fertilizer 6-8 weeks before first frost. Late feeding promotes tender growth that’s damaged by cold.

🧪 Soil Test First

Test soil every 2-3 years. You may already have adequate nutrients! Testing prevents waste and over-application.

⚠️ Signs of Over-Fertilization:

Brown, crispy leaf tips and edges
White crust on soil surface (salt buildup)
Wilting despite adequate water
Yellowing lower leaves
Stunted growth or leggy plants