Best Fall Bulb Fertilizer (5-10-10): High P & K to Build Root Reserves Before Winter Dormancy Buy on Old Cobblers Farm
Fall-planted bulbs have one job before winter: grow roots and store energy. They don't need nitrogen pushing top growth that will freeze. This 5-10-10 delivers double the P and K relative to nitrogen — loading the bulb with the reserves it needs for a spectacular spring show.
Old Cobblers Farm™ Wicked Growth Fall Bulb Fertilizer
by Conventional Fertilizer — Littleton, NH
Built for Bulb Biology
Bulbs planted in fall need root development, not leaf growth. 5% nitrogen stays low enough to avoid triggering foliage before winter, while 10% P and 10% K build the underground infrastructure.
10% Phosphorus for Root Establishment
Phosphorus drives the rapid root growth bulbs need during the fall rooting window. Strong roots mean better water and nutrient uptake when spring arrives.
10% Potassium for Energy Storage
Potassium helps bulbs store carbohydrates and regulate water balance heading into dormancy. Well-charged bulbs produce larger flowers with stronger stems.
Per-Bulb or Per-Bed Rates
1–2 tablespoons per individual bulb planting hole, or 1–2 lbs per 100 sq ft broadcast over entire bulb beds. Flexible for any planting method.
320 Bulbs Per Bag
At 1 tbsp per bulb, one 5 lb bag fertilizes up to 320 individual bulb plantings. For beds, covers 250–500 sq ft.
Fall + Spring Schedule
Apply at fall planting to fuel root growth, then top-dress again at spring emergence to support stem elongation and bloom development.
All Bulb Types
Tulips, daffodils, crocuses, hyacinths, alliums, lilies, muscari, snowdrops, fritillaria — every fall-planted bulb benefits from this P & K-forward formula.
Trusted by 20,000+ Growers
Developed in Littleton, New Hampshire. Sold nationwide on Amazon, Walmart, eBay, and theoldcobblersfarm.com.
| NPK Ratio | 5-10-10 |
| Item Form | Granular |
| Coverage | 250–500 sq ft bulb beds | 160–320 bulbs per 5 lb bag |
| Category | Conventional Fertilizer |
| Type | Starters & Boosters |
| Sizes | 5 lb | 10 lb | 15 lb | 20 lb |
| NPK | 5-10-10 |
| Nitrogen | 5% |
| Phosphorus | 10% available phosphate |
| Potassium | 10% soluble potash |
| Form | Granular |
| Rate | 1–2 tbsp / bulb or 1–2 lbs / 100 sq ft |
| Method | Incorporate or broadcast |
| Frequency | 1x fall + 1x spring |
| Sizes | 5, 10, 15, 20 lb bags |
| Best For | Tulips, daffodils, crocuses, hyacinths, alliums, lilies, all fall bulbs |
| Feature | Old Cobblers Farm™ Wicked Growth Fall Bulb Fertilizer Old Cobblers Farm | Bulb-Tone Organic Espoma | Bloom Booster Flower Food Miracle-Gro | All Purpose 5-10-5 Expert Gardener | Great Gardens Gro Green | Gro-Fine All Purpose Knox Fertilizer | Nutra Green Monterey | Balanced Fertilizer Shur-Crop | 10-10-10 All Purpose GroundWork | Bulb Food Spikes Jobe's Organics | Flower & Vegetable Scotts |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPK | 5-10-10 | 4-6-6 | 10-52-10 | 5-10-5 | 5-10-5 | 5-10-5 | 5-10-5 | 18-18-18 | 10-10-10 | 3-5-4 | 10-10-10 |
| Form | Granular | — | — | — | — | — | — | — | — | — | — |
| Coverage | 250–500 sq ft bulb beds | 160–320 bulbs per 5 lb bag | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed |
| Price / Size | 5 lb | 10 lb | 15 lb | 20 lb | $9.99 | $10.49 | $17.96 | $31.29 | $33.47 | $26.43 | $44.99 | $19.99 | $12.99 | $11.00 |
| Our Take | The purpose-built fall bulb formula. Low nitrogen prevents prematur... | — | — | — | — | — | — | — | — | — | — |
Bulb-Tone Organic
Bloom Booster Flower Food
All Purpose 5-10-5
Great Gardens
Gro-Fine All Purpose
Nutra Green
Balanced Fertilizer
10-10-10 All Purpose
Bulb Food Spikes
Flower & Vegetable
Built for Bulb Biology
Bulbs planted in fall need root development, not leaf growth. 5% nitrogen stays low enough to avoid triggering foliage before winter, while 10% P and 10% K build the underground infrastructure.
10% Phosphorus for Root Establishment
Phosphorus drives the rapid root growth bulbs need during the fall rooting window. Strong roots mean better water and nutrient uptake when spring arrives.
10% Potassium for Energy Storage
Potassium helps bulbs store carbohydrates and regulate water balance heading into dormancy. Well-charged bulbs produce larger flowers with stronger stems.
Per-Bulb or Per-Bed Rates
1–2 tablespoons per individual bulb planting hole, or 1–2 lbs per 100 sq ft broadcast over entire bulb beds. Flexible for any planting method.
