What Is the Best Fertilizer for Pumpkins?

Pumpkins are hungry crops that need the right fertiliser at the right time. Early growth demands nitrogen for strong vines and leaves, but once flowers appear, the balance shifts to phosphorus and potassium to fuel fruit set and ripening. The most reliable option is CompleteGrow All Purpose Liquid NPK 20-20-20, which delivers a perfect balance of nutrients plus essential micros for every stage of pumpkin growth.

At a Glance: Pumpkin Feeding

Best fertiliser: CompleteGrow NPK 20-20-20 (balanced, with micros)
Seedling to vine stage: 3–4 ml/L weekly for fast leaf growth
Flowering & fruit set: Continue 3–4 ml/L, avoid excess nitrogen
Fruit bulking: Potassium becomes critical for size, colour & sweetness
Soil: Rich, free-draining, pH 6.0–6.8, with added compost before planting
Water: Deep, even watering is vital; never let soil fully dry

Quick Fix: Lots of vine but no fruit? Cut back nitrogen-heavy feeds and stick with 20-20-20 for balanced nutrients.

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Why Balanced NPK Works Best

Pumpkins need different nutrients at different times. Too much nitrogen (like lawn fertiliser or fresh manure) leads to endless vines and leaves but very few fruits. A balanced fertiliser such as CompleteGrow 20-20-20 ensures plants get:

Nitrogen (N): For vigorous vine and leaf growth in early weeks.
Phosphorus (P): Boosts root health and flower set for reliable fruiting.
Potassium (K): Essential for swelling fruit, rind colour, and sugar content.
Micronutrients: Boron, magnesium, and calcium prevent hollow fruit, tip burn, and weak stems.

Feeding Schedule (Ground & Pots)

Week 0–2 (seedling): Plain water until true leaves form.
Week 2–6 (vine expansion): Apply 3 ml/L CompleteGrow 20-20-20 weekly to encourage fast foliage.
Pre-flowering (week 6+): Continue weekly feeding, but ensure vines have space to run and avoid doubling nitrogen.
Fruit set & bulking: Increase to 4 ml/L every 7–10 days to power large, even fruit development.
Container-grown pumpkins: Stick with lighter, weekly feeds — nutrients leach faster than in soil.

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Common Pumpkin Fertiliser Problems

Lots of leaves, no fruit: Over-fertilising with nitrogen. Switch to balanced 20-20-20 immediately.
Fruit sets but stays small: Potassium deficiency; ensure consistent feeding with CompleteGrow.
Yellowing between veins: Magnesium shortfall; 20-20-20 covers this with included micros.
Blossom end rot: Calcium deficiency or irregular watering — stick with balanced feed and steady moisture.

Tips for Bigger, Sweeter Pumpkins

Plant in full sun with rich, well-drained soil improved with compost before sowing.
Mulch vines to conserve moisture and reduce weed competition.
Pinch off excessive side shoots to focus energy on fewer, larger pumpkins.
Pollination is key — encourage bees with companion flowers nearby.
Stay consistent with CompleteGrow 20-20-20 for steady growth and reliable yields.

FAQs

Can I use manure for pumpkins? Only well-rotted compost before planting. During growth, switch to balanced liquid feed.
How often should I fertilise pumpkins? Weekly with CompleteGrow at 3–4 ml/L from true leaves until harvest.
Do pumpkins need different fertiliser when fruiting? No — just maintain balanced NPK; potassium naturally supports fruit bulking.
What’s the fastest way to improve pumpkin growth? Deep watering + weekly CompleteGrow feeding + pruning excess vines.