Best Tomato Fertilizer (10-5-13): Polymer-Coated Slow Release with Calcium to Prevent Blossom End Rot Buy on Old Cobblers Farm
Blossom end rot isn't a disease — it's a calcium deficiency. Most tomato fertilizers ignore it entirely. This 10-5-13 includes calcium from gypsum, magnesium from langbeinite, and polymer-coated slow-release nitrogen — the complete package for tomatoes that actually fruit without problems.
Old Cobblers Farm™ Wicked Growth Tomato Fertilizer 10-5-13
by Conventional Fertilizer — Littleton, NH
Stops Blossom End Rot at the Source
Calcium sulphate (gypsum) delivers plant-available calcium directly to the root zone. Consistent calcium uptake prevents the black, sunken fruit bottoms that ruin harvests.
Polymer-Coated Slow Release
Purkote-coated urea releases nitrogen gradually over weeks. No surge-and-crash feeding cycle — steady nutrition from transplant through final harvest.
13% Potassium for Flavor & Firmness
Potassium drives sugar accumulation (Brix), enhances red color development, improves flesh firmness, and extends shelf life. The difference between a mediocre tomato and a great one.
Sulfur & Magnesium Built In
Langbeinite provides magnesium for chlorophyll production and sulfur for protein synthesis and flavor compound development. No separate amendments needed.
Per-Plant Dosing
1.5 tablespoons per plant for side-dressing — simple and precise. One 5 lb bag feeds approximately 53 tomato plants per application.
6-Ingredient Professional Blend
Six precision ingredients deliver three primary nutrients plus three secondary nutrients in a single slow-release granule. No other tomato fertilizer packs this much into one product.
All Tomato Types & Setups
Beefsteak, cherry, roma, heirloom, grape — determinate or indeterminate. Works in beds, raised beds, containers, grow bags, and high tunnels.
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 | 170–250 sq ft (broadcast) | ~53 tomato 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 | 1.5 tbsp / plant or 2–3 lbs / 100 sq ft |
| Method | Side-dress or broadcast |
| Frequency | 2–3x per season |
| Sizes | 5, 10, 15, 20 lb bags |
| Best For | All tomato varieties — beefsteak, cherry, roma, heirloom |
| Feature | Old Cobblers Farm™ Wicked Growth Tomato Fertilizer 10-5-13 Old Cobblers Farm | Tomato-Tone Organic Espoma | Home Grown Tomato/Veg Dr. Earth | Water Soluble Tomato Miracle-Gro | Tomato & Vegetable Alaska | Vegetable & Tomato Food Jobe's Organics | Tomato & Vegetable Food Vigoro | Organics Vegetable/Tomato Expert Gardener | Smart-Release Flower/Veg Osmocote | Tomato & Vegetable Nutrients MasterBlend | Tomato & Vegetable Food True Organic |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPK | 10-5-13 | 3-4-6 | 4-6-3 | 18-18-21 | 3-6-6 | 2-5-3 | 12-10-5 | 3-4-4 | 14-14-14 | 4-18-38 | 4-5-6 |
| Form | Slow-release granular (polymer coated) | — | — | — | — | — | — | — | — | — | — |
| Coverage | 170–250 sq ft (broadcast) | ~53 tomato 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 | $14.99 | $11.99 | $7.99 | $9.99 | $13.50 | $5.97 | $5.97 | $22.97 | $24.99 | $23.88 |
| Our Take | The most complete tomato fertilizer available. Slow-release nitroge... | — | — | — | — | — | — | — | — | — | — |
Tomato-Tone Organic
Home Grown Tomato/Veg
Water Soluble Tomato
Tomato & Vegetable
Vegetable & Tomato Food
Tomato & Vegetable Food
Organics Vegetable/Tomato
Smart-Release Flower/Veg
Tomato & Vegetable Nutrients
Tomato & Vegetable Food
Stops Blossom End Rot at the Source
Calcium sulphate (gypsum) delivers plant-available calcium directly to the root zone. Consistent calcium uptake prevents the black, sunken fruit bottoms that ruin harvests.
Polymer-Coated Slow Release
Purkote-coated urea releases nitrogen gradually over weeks. No surge-and-crash feeding cycle — steady nutrition from transplant through final harvest.
13% Potassium for Flavor & Firmness
Potassium drives sugar accumulation (Brix), enhances red color development, improves flesh firmness, and extends shelf life. The difference between a mediocre tomato and a great one.
Sulfur & Magnesium Built In
Langbeinite provides magnesium for chlorophyll production and sulfur for protein synthesis and flavor compound development. No separate amendments needed.
