Guaranteed Analysis
Nutrient Breakdown
N · Nitrogen16%
Provides 16% nitrogen (from urea and polymer-coated urea for extended release) to fuel vigorous growth. The Purkote slow-release component feeds for 6-8 weeks per application, reducing the total number of applications needed per season.
P · Phosphorus10%
Delivers 10% phosphorus (from monoammonium phosphate) to promote deep root development and support establishment of new plantings and perennial crowns
K · Potassium13%
Supplies 13% potassium (from muriate of potash and potassium magnesium sulfate) to strengthen cell walls, improve disease resistance, and enhance winter hardiness
Derived from: Urea, Purkote (Polymer Coated Urea), Monoammonium Phosphate, Potassium Chloride (Muriate of Potash), Potassium Magnesium Sulfate, Silicon Dioxide. Also provides 2% Sulfur, 7% Calcium, 1% Magnesium.
Overview
What It Is
This 16-10-13 formula is the same blend as Old Cobblers Farm's Asparagus Fertilizer—both are produced by Green Mountain Fertilizer using identical ingredients and ratios. The six-ingredient composition (urea, Purkote polymer-coated urea, monoammonium phosphate, muriate of potash, potassium magnesium sulfate, silicon dioxide) provides higher total nutrient content than standard balanced fertilizers.
The dual nitrogen delivery system combines urea for immediate availability with Purkote for sustained release, matching how plants actually use nitrogen—in steady doses over time rather than one massive spike. The 7% calcium from the mineral components is exceptionally valuable as a secondary nutrient, particularly for crops prone to calcium-related quality issues like blossom-end rot.
Crop Fit
Best For
AsparagusCornPerennialsLawnsFood PlotsPasturesHeavy-Feeding CropsOrnamentals
This formula excels for nitrogen-demanding crops: asparagus needs high N for fern production, corn requires heavy nitrogen, and actively growing lawns benefit from the higher nitrogen ratio. Food plots for deer and wildlife respond well to the balanced-with-higher-N approach. Perennial flower beds and ornamental plantings use this for establishment and spring recovery. The 7% calcium makes it particularly valuable for any crop prone to calcium-related quality issues.
Application Rates
How Much to Use
| Garden & beds | 0.5-1 lb per 100 sq ft at pre-planting; 0.25-0.5 lbs per 100 sq ft for established beds in spring and post-harvest |
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| Lawn | 3-5 lbs per 1,000 sq ft for established lawns needing balanced nutrition with higher nitrogen |
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| Trees & shrubs | 0.5-1 lb per inch of trunk diameter for ornamental and shade trees |
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| Containers | 1-2 teaspoons per plant, sprinkled 4-6 inches around the base |
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| Frequency | 2-3 times per growing season: early spring before active growth, mid-season to support continued production, and optionally late summer at half rate if soil tests indicate depletion |
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Step by Step
How to Apply
1Soil Test
Test soil before the season to determine nutrient needs. This balanced formula works well for general-purpose feeding.
2Garden Broadcast
Broadcast 0.5–1.5 lbs per 100 sq ft before planting or in early spring for established beds.
3Lawn Rate
For lawns, apply 3–5 lbs per 1,000 sq ft with a calibrated broadcast or drop spreader for even coverage.
4Side-Dress
Side-dress nitrogen-hungry crops (corn, leafy greens, brassicas) every 4–6 weeks during the growing season.
5Water In
Water thoroughly after each application to prevent burn and activate nutrient release.
6Monitor
Monitor crop response and adjust rates accordingly. Excessive leaf growth with poor fruiting may indicate too much nitrogen.
Apply using standard broadcast methods. For garden beds, incorporate 0.5-1.5 lbs per 100 sq ft into soil before planting. For established perennials, broadcast over the bed surface in early spring and water in. For lawns, use a calibrated spreader at 3-5 lbs per 1,000 sq ft. The polymer-coated urea means each application feeds for 6-8 weeks, so most crops need only 2-3 applications per season. For commercial production, apply 100-200 lbs per acre. This is the same formulation as Old Cobblers Farm™ Asparagus Fertilizer—apply using the same rates and methods.
Handling & Timing
Safety & Season
Safety & Storage
Wear protective gloves and eye protection during handling. Avoid breathing dust—use a NIOSH-approved dust respirator if applying in windy conditions. Wash hands thoroughly after handling. Store in a cool, dry, well-ventilated area protected from weather. Slightly reactive with oxidizing agents, metals, alkalis, and moisture—keep sealed when not in use. Prevent entry to sewers and surface waters. Keep out of reach of children and pets.
Seasonal Notes
Spring: Primary application window. Apply as growth begins for perennials, lawns, and garden beds. Incorporate before planting annuals. Summer: Continue applications every 4-6 weeks for actively growing crops. The slow-release component reduces mid-season application frequency. Fall: Light application for cool-season grasses and fall gardens. Winter: No application. Plan soil testing.
In Context
How It Compares
The 16-10-13 provides 60% more nitrogen per pound than standard 10-10-10, making it more cost-effective for nitrogen-hungry crops. Compared to straight urea (46-0-0), this blend adds essential phosphorus, potassium, and secondary nutrients in a single application. The polymer-coated urea component provides longer feeding than fast-release-only competitors. The 7% calcium exceeds what most general-purpose fertilizers offer. This is the same formulation as Old Cobblers Farm™ Asparagus Fertilizer.
Answers
Frequently Asked Questions
What is 16-10-13 fertilizer used for?
16-10-13 fertilizer is a high-nitrogen, balanced formula designed for plants that need vigorous growth combined with strong root systems and stress resistance. The elevated nitrogen (16%) drives lush foliage and rapid canopy development, phosphorus (10%) supports deep root growth and crown structure, and potassium (13%) enhances disease resistance and environmental tolerance. It is especially effective for asparagus, turfgrass, and heavy-feeding crops that demand sustained nitrogen throughout the growing season. Old Cobblers Farm™ Wicked Growth 16-10-13 Fertilizer with added sulfur and magnesium is a premium option for targeted plant nutrition.
Is 16-10-13 good for asparagus?
Yes, 16-10-13 is an excellent fertilizer for asparagus. The high nitrogen content encourages strong fern growth after the harvest season, which is critical for building carbohydrate reserves in the crown for next year's spear production. Phosphorus supports the deep root systems asparagus needs as a perennial crop, and potassium improves stress tolerance and overall plant resilience. When formulated with added sulfur and magnesium, 16-10-13 optimizes nutrient uptake and chlorophyll production. Old Cobblers Farm™ Wicked Growth Asparagus Fertilizer 16-10-13 is specifically designed for both new and established asparagus beds.
How much 16-10-13 fertilizer should I apply?
Application rates for 16-10-13 fertilizer depend on the crop. For asparagus, apply in early spring before spears emerge and again in late summer after the harvest season. For lawns, apply 5–8 pounds per 1,000 square feet during active growth. For general garden use, broadcast 2–3 pounds per 100 square feet and incorporate into the top few inches of soil. Always water thoroughly after application. The elevated nitrogen content means less product is needed to achieve the same nitrogen input compared to lower-analysis fertilizers. Old Cobblers Farm™ Wicked Growth 16-10-13 is fast-acting and effective when watered in.
What does sulfur and magnesium do in fertilizer?
Sulfur and magnesium are essential secondary nutrients that enhance plant growth and nutrient uptake. Sulfur is critical for amino acid synthesis, enzyme function, and chlorophyll formation — without adequate sulfur, plants cannot efficiently use nitrogen. Magnesium is the central atom in the chlorophyll molecule and directly drives photosynthesis. Together, they help plants produce more energy, maintain greener foliage, and utilize primary nutrients (N-P-K) more effectively. Old Cobblers Farm™ Wicked Growth 16-10-13 Fertilizer includes both sulfur and magnesium to maximize nutrient efficiency and promote healthy, vibrant plant growth.
Can I use 16-10-13 on my lawn?
Yes, 16-10-13 is well-suited for lawns, particularly cool-season turfgrass that responds well to higher nitrogen applications. The 16% nitrogen promotes thick, green growth and canopy density, phosphorus builds strong root systems for better drought tolerance, and potassium strengthens the turf against disease, heat, and traffic. Apply 5–8 pounds per 1,000 square feet during spring or fall for best results. Old Cobblers Farm™ Wicked Growth 16-10-13 Fertilizer delivers premium, high-performance nutrition for lawns that demand more than a basic fertilizer can provide.
When should I fertilize asparagus?
Fertilize asparagus twice per year — first in early spring before spears begin to emerge, and again in late summer or early fall after the harvest season ends and ferns are actively growing. The spring application fuels spear production, while the fall application supports fern growth and carbohydrate storage in the crown for next year's harvest. Avoid fertilizing during the active harvest period. For newly planted crowns, apply at planting and again mid-summer. Old Cobblers Farm™ Wicked Growth Asparagus Fertilizer 16-10-13 with sulfur and magnesium is optimized for both application windows.
What NPK ratio is best for asparagus?
Asparagus performs best with a higher-nitrogen fertilizer that also provides strong phosphorus and potassium. A ratio like 16-10-13 is ideal because the elevated nitrogen supports vigorous fern growth, which is how asparagus builds energy reserves for the following spring's spear production. Phosphorus maintains healthy crowns and root systems, while potassium enhances disease resistance and winter hardiness. Added sulfur and magnesium further optimize nutrient uptake and promote green, healthy fern development. Old Cobblers Farm™ Wicked Growth Asparagus Fertilizer 16-10-13 is specifically formulated with the optimal NPK ratio for asparagus.
