NPK Fertilisers

NPK fertilisers are essential plant nutrients that provide the three most important elements needed for healthy plant growth: Nitrogen (N), Phosphorus (P), and Potassium (K). Each element plays a vital role – Nitrogen promotes leaf and stem growth, Phosphorus helps develop strong roots and flowers, while Potassium improves overall plant health and disease resistance. Think of NPK as your plants’ complete nutrition package, much like a balanced diet is essential for human health. Whether you’re growing vegetables, maintaining a lush lawn, or nurturing flowering plants, using the right NPK ratio ensures your plants get the perfect balance of nutrients they need to thrive.

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Scotts Lawn Builder Extreme Green Slow Release Fertiliser - 2.5kg
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Scotts Lawn Builder Extreme Green Slow Release Fertiliser

2 reviews $34.90

Understanding NPK Ratios and Applications

Every NPK fertilisers displays three numbers (like 10-5-5) representing the percentage of Nitrogen (N), Phosphorus (P), and Potassium (K). Understanding these ratios helps you choose the right fertilizer for specific plants and growth stages.

Learn more about NPK fertiliser in our complete guide.

Key Nutrient Function on NPK Fertilisers:

  • Nitrogen (N): Promotes leafy growth, enhances green color, and builds protein structures
  • Phosphorus (P): Develops strong root systems, supports flowering and fruiting
  • Potassium (K): Strengthens plant resistance, improves water usage, and enhances fruit quality

Recommended NPK Ratios for Different Plants:

Vegetables:
  • Leafy Greens (Lettuce, Spinach): High nitrogen (20-10-10) Other suitable are: (12-4-8 or 15-5-15)
  • Tomatoes: Balanced while growing (9-1.5-7), higher potassium when fruiting (6-8-12)
  • Root Vegetables: Lower nitrogen, higher phosphorus (5-10-10)
Lawns:
  • New Lawns:  (10-10-10) or in higher phosphorous such as (16-8-8 or 20-10-10)
  • Established Lawns:  (3-1-2 or 4-1-2)
Flowering Plants:
  • During Growth: Balanced feed (10-30-20)
  • Pre-flowering:  (10-10-5)
  • Blooming Period: (6-5-6)
 Fruit Trees:
  • Spring Growth: Balanced NPK (10-10-10)
  • Fruit Development: Higher potassium (6-6-12)
  • Post-harvest: Lower nitrogen (3-5-10)
Native Plants:
  • Generally prefer low phosphorus (10-3-6)
  • Use native-specific formulas for best results