How to Fertilize Squash
Feed these hungry plants for bountiful summer and winter harvests
Quick Reference
Summer vs. Winter Squash
Summer Squash
Zucchini, yellow squash, pattypan
- • Harvested immature, continuous picking
- • Steady fertilizing for constant production
- • Feed every 2 weeks during harvest
- • Balanced nutrition throughout
Winter Squash
Butternut, acorn, spaghetti, pumpkins
- • Harvested mature, longer growing season
- • Extra potassium helps storage
- • Reduce nitrogen as fruit matures
- • Let vines die back naturally
Fertilizing by Growth Stage
At Planting
Mix generous compost into planting area - squash love rich soil. Add balanced slow-release fertilizer. Create a slight mound for better drainage.
Vine Development
Feed every 2-3 weeks with balanced fertilizer (10-10-10). Plants need nitrogen to establish extensive vine systems before fruiting.
Flowering & FruitingKey Stage
Switch to low-nitrogen fertilizer (5-10-10). Continue feeding every 2-3 weeks. Phosphorus and potassium support fruit development.
Late Season (Winter Squash)
For winter squash, stop fertilizing 3-4 weeks before harvest. Let plants focus energy on maturing existing fruit rather than new growth.
Best Fertilizers for Squash
Organic Options
- • Compost - Essential for squash success
- • Aged manure - Rich, balanced feeding
- • Fish emulsion - Quick nitrogen boost
- • Bone meal - Phosphorus for fruit
- • Wood ash - Potassium for winter squash
Synthetic Options
- • 10-10-10 - Balanced, for early growth
- • 5-10-10 - For flowering/fruiting
- • Tomato fertilizer - Works well
- • Slow-release granular - Convenient
- • 0-10-10 - Winter squash maturation
Common Squash Fertilizing Mistakes
- • Too much nitrogen - Massive vines with few squash
- • Fertilizing at base of stem - Can cause rot; apply in a ring around plant
- • Ignoring the soil - Squash need rich, amended soil to start
- • Late fertilizing (winter squash) - Stop feeding to let fruit mature
Signs Your Squash Need Fertilizer
Yellow Older Leaves
Nitrogen deficiency - apply fish emulsion or balanced fertilizer.
Poor Fruit Set
May need phosphorus boost. Also check pollination - hand pollinate if needed.
Stunted Growth
Overall nutrient deficiency - apply balanced fertilizer and check soil pH.
Blossom End Rot
Calcium issue, often from inconsistent watering rather than fertilizer deficiency.
Frequently Asked Questions
How often should I fertilize squash?
Fertilize squash every 2-3 weeks during the growing season. They're heavy feeders that benefit from consistent nutrition throughout their long production period.
What's the best fertilizer for squash?
Use a balanced fertilizer (10-10-10) early on, then switch to lower nitrogen (5-10-10) when flowering begins. Too much nitrogen causes all vine and no fruit.
Do summer and winter squash have different fertilizer needs?
They have similar needs, but winter squash benefits from extra potassium late in the season to help fruit mature and store well. Summer squash needs steady feeding for continuous harvest.
Why are my squash plants all leaves and no fruit?
Too much nitrogen encourages leafy growth over fruit production. Switch to a low-nitrogen, high-phosphorus fertilizer and make sure flowers are being pollinated.