Best Strawberry Fertilizer (10-5-13): High Potassium for Sweeter, Larger Berries with Slow-Release Feeding Buy on Old Cobblers Farm
Strawberry sweetness is driven by potassium. Berry size is driven by potassium. Shelf life is driven by potassium. This 10-5-13 delivers 13% K with slow-release nitrogen and built-in calcium, magnesium, and sulfur — purpose-built for strawberry biology.
Old Cobblers Farm™ Wicked Growth Strawberry Fertilizer 10-5-13
by Conventional Fertilizer — Littleton, NH
13% Potassium for Sweeter Berries
Potassium is the #1 nutrient that determines strawberry sweetness (Brix), berry size, flesh firmness, and how long berries hold after picking. More K = better fruit.
Slow-Release Won't Overpush Runners
Excess quick-release nitrogen triggers aggressive runner production at the expense of fruit. Polymer-coated slow release feeds the crown steadily without the runner explosion.
Calcium Prevents Tip Burn
Gypsum-sourced calcium prevents leaf tip burn and fruit deformity caused by calcium deficiency — common in fast-growing strawberry beds with inconsistent watering.
Per-Plant Precision
1 tablespoon per plant for side-dressing around the crown. One 5 lb bag feeds approximately 160 strawberry plants per application.
500 sq ft at Broadcast Rate
At 1 lb per 100 sq ft, one 5 lb bag covers 500 sq ft of strawberry bed — the best coverage-per-bag ratio for any specialty fruiting formula.
3-Phase Strawberry Program
Feed early spring at growth resumption, again after the main harvest for crown recovery, and at fall renovation for next year's bud set. Three feeds, one product.
All Strawberry Types
June-bearing, everbearing, day-neutral, and alpine strawberries. Works in matted rows, raised beds, containers, hanging baskets, and tower planters.
Trusted by 20,000+ Growers
Developed in Littleton, New Hampshire. Sold nationwide on Amazon, Walmart, eBay, and theoldcobblersfarm.com.
| NPK Ratio | 10-5-13 |
| Item Form | Slow-release granular (polymer coated) |
| Coverage | 500 sq ft (broadcast) | ~160 plants per 5 lb bag |
| Category | Conventional Fertilizer |
| Type | Flower & Garden |
| Sizes | 5 lb | 10 lb | 15 lb | 20 lb |
| NPK | 10-5-13 |
| Nitrogen | 10% (polymer coated) |
| Phosphorus | 5% available phosphate |
| Potassium | 13% soluble potash |
| Secondary | Calcium, Magnesium, Sulfur |
| Form | Slow-release granular |
| Rate | 1 tbsp / plant or 1 lb / 100 sq ft |
| Method | Side-dress or broadcast |
| Frequency | 2–3x per season |
| Sizes | 5, 10, 15, 20 lb bags |
| Best For | All strawberry varieties — June-bearing, everbearing, day-neutral, alpine |
| Feature | Old Cobblers Farm™ Wicked Growth Strawberry Fertilizer 10-5-13 Old Cobblers Farm | Berry-Tone Organic Espoma | Strawberry Part A Jack's Nutrients | Natural Wonder Fruit Tree Dr. Earth | Cottonseed Meal Down To Earth | Fruit & Bloom Booster Farmer's Secret | Fruit & Citrus Spikes Jobe's Organics | Organic All Purpose Vigoro | Organic Berry Fertilizer Ludicrous Nutrients | Potassium Nitrate Duda Energy | Fruit Tree Mix Down To Earth |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPK | 10-5-13 | 4-3-4 | 8-10-16 | 5-5-2 | 6-2-1 | Liquid | 3-5-5 | 5-5-5 | Liquid | 13-0-44 | 6-2-4 |
| Form | Slow-release granular (polymer coated) | — | — | — | — | — | — | — | — | — | — |
| Coverage | 500 sq ft (broadcast) | ~160 plants 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 | $11.99 | $31.79 | $12.47 | $54.98 | $14.99 | $24.35 | $10.97 | $24.99 | $22.65 | $19.99 |
| Our Take | The strawberry specialist with 13% potassium for maximum Brix (suga... | — | — | — | — | — | — | — | — | — | — |
Berry-Tone Organic
Strawberry Part A
Natural Wonder Fruit Tree
Cottonseed Meal
Fruit & Bloom Booster
Fruit & Citrus Spikes
Organic All Purpose
Organic Berry Fertilizer
Potassium Nitrate
Fruit Tree Mix
13% Potassium for Sweeter Berries
Potassium is the #1 nutrient that determines strawberry sweetness (Brix), berry size, flesh firmness, and how long berries hold after picking. More K = better fruit.
Slow-Release Won't Overpush Runners
Excess quick-release nitrogen triggers aggressive runner production at the expense of fruit. Polymer-coated slow release feeds the crown steadily without the runner explosion.
Calcium Prevents Tip Burn
Gypsum-sourced calcium prevents leaf tip burn and fruit deformity caused by calcium deficiency — common in fast-growing strawberry beds with inconsistent watering.
Per-Plant Precision
1 tablespoon per plant for side-dressing around the crown. One 5 lb bag feeds approximately 160 strawberry plants per application.
