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Old Cobblers Farm™ Wicked Growth 10-5-13 Fertilizer – High Potassium Blend

Versatile 10-5-13 fertilizer with 13% sulfur and 3% calcium for gardens, berries & vegetables. Application rates & tips from Old Cobblers Farm.

Old Cobblers Farm™ Wicked Growth 10-5-13 Fertilizer – High Nitrogen-Phosphate

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OUR STORY

This 10-5-13 formula is the general-purpose version of Old Cobblers Farm's Strawberry and Tomato Fertilizers—all three share the same Green Mountain Fertilizer formulation. The six-ingredient composition (ammonium sulfate, Purkote, MAP, MOP, potassium magnesium sulfate, gypsum) provides a complete nutritional package with secondary nutrients that most generic fertilizers lack.

The dual nitrogen sources ensure 6-8 weeks of sustained feeding per application. The low-phosphorus design makes this compliant with phosphorus restrictions in many states while still providing enough P for maintenance. The rich secondary nutrient profile—13% sulfur, 3% calcium, 3% magnesium—addresses deficiencies increasingly common in Northeast soils that basic NPK fertilizers miss entirely.

NPK

10-5-13

Type

Non-Organic

Derived From

Ammonium Sulfate, Purkote (Polymer Coated Urea), Monoammonium Phosphate, Potassium Chloride (Muriate of Potash), Potassium Magnesium Sulfate, Calcium Sulfate (Gypsum). Also provides 13% Sulfur, 3% Calcium, 3% Magnesium.

Best For

Brand

Wicked Growth

NPK Breakdown

N

Provides 10% nitrogen (from ammonium sulfate and polymer-coated urea) for steady growth without the excessive vegetative push that reduces fruit quality in fruiting crops

P

Delivers 5% phosphorus (from monoammonium phosphate) for root establishment and flower initiation—kept intentionally low to avoid phosphorus buildup in established soils

K

Supplies 13% potassium (from muriate of potash and potassium magnesium sulfate) to improve fruit quality, firmness, flavor, color development, and disease resistance

What Is It ?

The 10-5-13 fertilizer is a versatile, high-potassium granular blend that delivers balanced nutrition with emphasis on fruit quality and plant vigor across a wide range of garden and farm crops. Unlike conventional 10-10-10 or 15-15-15 fertilizers, this formula is intentionally designed with higher potassium and lower phosphorus—reflecting modern agronomic understanding that most established soils have adequate phosphorus but need potassium replenishment. The 10% nitrogen comes from dual sources: fast-acting ammonium sulfate and slow-release polymer-coated urea (Purkote), providing both immediate and sustained feeding. The 5% phosphorus provides enough for root maintenance without phosphorus overload. The 13% potassium drives fruit quality, disease resistance, and stress tolerance. Bonus nutrients include 13% sulfur, 3% calcium, and 3% magnesium. This is the same formulation as Old Cobblers Farm™ Strawberry Fertilizer and Tomato Fertilizer, available as a general-purpose product for gardeners who want one fertilizer that works across their entire garden. Manufactured by Green Mountain Fertilizer in Milton, Vermont.

When To Apply ?

For garden beds, broadcast 0.75-1.5 lbs per 100 sq ft and incorporate into the top 4-6 inches before planting. For established crops, side-dress every 3-4 weeks by creating a shallow trench 4-6 inches from stems. For lawns, apply 3-5 lbs per 1,000 sq ft with a calibrated spreader. For commercial acreage, apply 200-400 lbs per acre. Apply using the same rates and methods as Old Cobblers Farm™ Tomato Fertilizer and Strawberry Fertilizer.

How to Apply ?

1. Soil Test

Test soil to determine baseline nutrient levels. This blend is ideal when potassium is needed more than phosphorus.

2. Pre-Plant Broadcast

Broadcast 0.75–1.5 lbs per 100 sq ft before planting and incorporate into the top 4–6 inches of soil.

3. Side-Dress

Side-dress heavy-feeding crops (tomatoes, peppers, squash) every 3–4 weeks during the growing season at half the initial rate.

4. Container Rate

For containers, mix 1 tablespoon per gallon of soil at planting. Containers leach nutrients faster and may need more frequent feeding.

5. Water In

Water thoroughly after each application to dissolve granules and deliver nutrients to the root zone.

6. Adjust

Adjust rates based on crop response and follow-up soil tests. Yellowing leaves or poor fruit set may indicate need for rate adjustments.

7 Side-Dress

Side-dress heavy-feeding crops (tomatoes, peppers, squash) every 3–4 weeks during the growing season at half the initial rate.

How To Store

Wear protective gloves and eye protection during handling. Avoid breathing dust—use a NIOSH-approved respirator in dusty conditions. Wash hands thoroughly after handling. Store in a cool, dry, well-ventilated area protected from weather and moisture. Slightly reactive with oxidizing agents, metals, alkalis. Prevent entry to sewers and surface waters. Keep out of reach of children and pets.

FAQs

1. What is 10-5-13 fertilizer used for?

10-5-13 fertilizer is a high-potassium blend designed for plants that need strong fruiting, flowering, and stress resistance. The elevated nitrogen (10%) supports vigorous foliage and shoot growth, while moderate phosphorus (5%) promotes root development and early-stage strength. The high potassium (13%) improves fruit quality, disease resistance, and tolerance to drought and temperature extremes. This ratio is ideal for fruiting vegetables, berry crops, and landscape plants that benefit from extra potassium. Old Cobblers Farm™ Wicked Growth 10-5-13 Fertilizer delivers precision nutrition for gardens, turf, flowers, shrubs, and fruiting plants.

2. Is 10-5-13 good for strawberries?

Yes, 10-5-13 is an excellent fertilizer for strawberries. The nitrogen supports lush foliage and runner production, phosphorus encourages strong root development and flower formation, and the elevated potassium enhances berry size, sweetness, flavor, and overall plant resilience. Potassium also helps strawberry plants tolerate heat stress during fruiting and improves the storage quality of harvested berries. Apply at planting, side-dress during bloom, and reapply every 4–6 weeks. Old Cobblers Farm™ Wicked Growth Strawberry Fertilizer 10-5-13 with micronutrients is specifically tailored for juicy, flavorful strawberry harvests.

3. What crops benefit from high-potassium fertilizer?

Crops that benefit most from high-potassium fertilizers like 10-5-13 include fruiting vegetables (tomatoes, peppers, squash, cucumbers), berry crops (strawberries, blueberries, raspberries), root vegetables (potatoes, carrots, beets), fruit trees, and turfgrass under stress. Potassium is critical for water regulation within plant cells, disease resistance, fruit development, and overall plant strength. Crops in the fruiting stage have particularly high potassium demands. Old Cobblers Farm™ Wicked Growth 10-5-13 Fertilizer provides elevated potassium alongside balanced nitrogen and phosphorus for complete, crop-ready nutrition.

4. How often should I apply 10-5-13 fertilizer?

Apply 10-5-13 fertilizer every 4–6 weeks during the active growing season for most crops and plants. For vegetables, start at transplanting or when seedlings are established, and reapply through the fruiting period. For turf, apply in spring and fall for optimal results. For perennial plants and shrubs, two to three applications per season — spring, early summer, and late summer — provide steady nutrition. Always water thoroughly after application to activate the nutrients. Old Cobblers Farm™ Wicked Growth 10-5-13 Fertilizer is economical and effective for multi-season use across a wide range of plants.

5. What does high potassium do for plants?

High potassium strengthens plants in several important ways. It regulates the opening and closing of stomata (leaf pores), which controls water loss and improves drought tolerance. Potassium activates enzymes involved in photosynthesis and protein synthesis, enhances nutrient transport within the plant, and strengthens cell walls for better disease and pest resistance. In fruiting crops, potassium directly improves fruit size, color, sweetness, and firmness. It also helps plants tolerate cold and heat stress. Old Cobblers Farm™ Wicked Growth 10-5-13 Fertilizer provides elevated potassium at 13% to deliver these critical benefits.

6. Can I use 10-5-13 fertilizer on my lawn?

Yes, 10-5-13 works well on lawns, especially during periods of stress. The nitrogen promotes green growth and density, while the high potassium level strengthens the turf against drought, disease, heat, and heavy traffic. It is particularly effective as a late-summer or early-fall application when lawns need to build resilience heading into winter. The moderate phosphorus supports root development without excess. Old Cobblers Farm™ Wicked Growth 10-5-13 Fertilizer is versatile enough for lawns, gardens, flowers, shrubs, and fruiting plants.

7 What is the difference between 10-10-10 and 10-5-13 fertilizer?

The key difference is the nutrient emphasis. 10-10-10 is a balanced, all-purpose formula providing equal parts of all three macronutrients, making it a good general choice for most plants. 10-5-13 shifts the balance toward higher potassium and lower phosphorus, which is better suited for fruiting crops, stress resistance, and plants that need stronger cell structure. Use 10-10-10 when you want complete, even nutrition across all plant types, and use 10-5-13 when fruit quality, disease resistance, or drought tolerance is a priority. Old Cobblers Farm™ offers both formulas to match your specific growing needs.