Organic Blueberry Specialist

Best Organic Blueberry Fertilizer (4-6-4): Acid-Friendly Slow-Release Nutrition for Bigger Berries, Higher Yields & Healthier Bushes Buy on Old Cobblers Farm

Updated April 2026 By the Old Cobblers Farm Team

Old Cobblers Farm™ Wicked Organics Organic Blueberry Fertilizer

by Wicked Organics — Littleton, NH

4-6-4
N-P-K Ratio
"The organic blueberry formula built on NCO Pro-Holly. 4-6-4 from composted manure and natural minerals feeds blueberry's fine root system gently through microbial activity — supporting flower set, berry sizing, and new cane growth without salt damage."
4-6-4
Organic NPK
Pro-Holly
Acid-Lover Base
2x
Spring + Fall
4 Sizes
5, 10, 15, 20 lbs
🫐

Acid-Lover Base for Blueberries

NCO Pro-Holly is formulated for acid-loving species. Blueberries need pH 4.5–5.5 — this formula works within that acidic environment instead of fighting it.

🌸

6% Phosphorus for Flower Set

Higher phosphorus supports the flower bud development that determines next year's berry crop. More flower buds = more berries per bush.

🌿

Gentle on Fine Roots

Blueberry roots are extremely fine and fibrous — sensitive to salt burn from synthetic fertilizers. Slow-release organic nutrients feed without damaging the delicate root system.

📅

Spring + Fall Program

Spring application fuels bloom, fruit set, and berry sizing. Fall application supports root growth and builds the flower bud reserves for next year's crop.

🐔

Full-Spectrum Composted Manure

Beyond NPK, composted manure delivers calcium, trace minerals, and beneficial microbes that support the mycorrhizal fungi blueberries depend on for nutrient uptake.

⚠️

Add Sulfur Separately for pH

This formula provides nutrition but doesn't acidify soil. Test soil pH annually and apply elemental sulfur separately if pH drifts above 5.5.

✅

All Blueberry Types

Highbush, half-high, lowbush, rabbiteye, northern and southern highbush — every blueberry variety thrives on gentle organic feeding in acidic soil.

🇺🇸

Trusted by 20,000+ Growers

Developed in Littleton, New Hampshire. Sold nationwide on Amazon, Walmart, eBay, and theoldcobblersfarm.com.

NPK Ratio4-6-4
Derived FromComposted chicken manure, Natural mineral phosphate sources, Natural potassium sources (NCO Pro-Holly base)
Item FormGranular
Release SpeedSlow-release (biologically driven)
Application Rate2–3 lbs / 100 sq ft | 1 lb / 2 ft crown diameter (spring + fall)
MethodBroadcast at drip line
FrequencySpring + Fall (2x per season)
Sizes5 lb | 10 lb | 15 lb | 20 lb
SupportsAll blueberry varieties — highbush, half-high, lowbush, rabbiteye, northern highbush, southern highbush
SetupsBlueberry rows, backyard bushes, containers, raised beds (acidic mix), U-pick operations
What We Love
✓ NCO Pro-Holly base designed for acid-loving blueberries
✓ Gentle on fine fibrous root systems — no salt burn
✓ 6% phosphorus supports flower bud and berry development
✓ Full-spectrum nutrition from composted manure
✓ Spring + fall program aligned to blueberry growth cycle
Worth Noting
— Does not acidify soil — add elemental sulfur separately if needed
— Lower NPK than synthetic blueberry formulas — need more product
Buy on Old Cobblers Farm →
Available in 5 lb | 10 lb | 15 lb | 20 lb
Feature Old Cobblers Farm™ Wicked Organics Organic Blueberry Fertilizer Berry-Tone Natural & Organic Fertilizer Acid Mix Fertilizer Holly-Tone (widely used for blueberries) Acid Lovers Fertilizer Happy Frog Acid Loving Plants Fertilizer Holly Care Organic Fertilizer Berry Mix Organic Fertilizer Berry-Tone Holly-Tone Acid Mix Happy Frog Acid Loving Plants Natural Wonder Fruit Tree Acid Lovers Berry Food Azalea, Camellia & Rhododendron Berry Mix Holly Care
NPK 4-6-4 4-3-2004 4-3-2006 4-3-2004 3-4-2003 4-5-2003 4-6-2004 4-2-2004 4-3-2004 4-3-2004 4-3-2006 4-5-2003 5-5-2002 3-4-2003 5-4-2004 5-4-2003 4-2-2004 4-6-2004
Phosphorus 6.0% 3.0% 3.0% 3.0% 4.0% 5.0% 6.0% 2.0% 3.0% 3.0% 3.0% 5.0% 5.0% 4.0% 4.0% 4.0% 2.0% 6.0%
Potassium 4.0% 4.0% 6.0% 4.0% 3.0% 3.0% 4.0% 4.0% 4.0% 4.0% 6.0% 3.0% 2.0% 3.0% 4.0% 3.0% 4.0% 4.0%
Form Granular
Sizes 5 lb | 10 lb | 15 lb | 20 lb 4, 27 lb 4, 8, 18, 27, 36, 50 lb 1, 5, 15, 25, 50 lb 4 lb 1, 4, 12, 25 lb 1, 4 lb 4 lb 4, 8 lb 5, 25, 50 lb 10, 25, 50 lb
Release Speed Slow-release (biologically driven)
The Competition

Berry-Tone Natural & Organic Fertilizer

by Espoma
4-3-2004
N-P-K
Price$8–$10 / 4 lb; $17–$18 / 18 lb
Espoma Berry-Tone is the most recognized berry-specific organic fertilizer. Fertrell Berry Mix (4-2-4) is explicitly formulated for berries, including boron and zinc. The blueberry segment overlaps heavily with the evergreen/acid-loving category.

Acid Mix Fertilizer

by Down To Earth
4-3-2006
N-P-K
Price$13–$17 / 5 lb
Espoma Berry-Tone is the most recognized berry-specific organic fertilizer. Fertrell Berry Mix (4-2-4) is explicitly formulated for berries, including boron and zinc. The blueberry segment overlaps heavily with the evergreen/acid-loving category.

Holly-Tone (widely used for blueberries)

by Espoma
4-3-2004
N-P-K
Price$16–$18 / 8 lb
Espoma Berry-Tone is the most recognized berry-specific organic fertilizer. Fertrell Berry Mix (4-2-4) is explicitly formulated for berries, including boron and zinc. The blueberry segment overlaps heavily with the evergreen/acid-loving category.

Acid Lovers Fertilizer

by Dr. Earth
3-4-2003
N-P-K
Price$16–$17 / 4 lb
Espoma Berry-Tone is the most recognized berry-specific organic fertilizer. Fertrell Berry Mix (4-2-4) is explicitly formulated for berries, including boron and zinc. The blueberry segment overlaps heavily with the evergreen/acid-loving category.

Happy Frog Acid Loving Plants Fertilizer

by FoxFarm
4-5-2003
N-P-K
Price$15–$17 / 4 lb
Espoma Berry-Tone is the most recognized berry-specific organic fertilizer. Fertrell Berry Mix (4-2-4) is explicitly formulated for berries, including boron and zinc. The blueberry segment overlaps heavily with the evergreen/acid-loving category.

Holly Care Organic Fertilizer

by Fertrell
4-6-2004
N-P-K
Price$14.95 / 10 lb
Espoma Berry-Tone is the most recognized berry-specific organic fertilizer. Fertrell Berry Mix (4-2-4) is explicitly formulated for berries, including boron and zinc. The blueberry segment overlaps heavily with the evergreen/acid-loving category.

Berry Mix Organic Fertilizer

by Fertrell
4-2-2004
N-P-K
Price$13–$15 / 5 lb
Espoma Berry-Tone is the most recognized berry-specific organic fertilizer. Fertrell Berry Mix (4-2-4) is explicitly formulated for berries, including boron and zinc. The blueberry segment overlaps heavily with the evergreen/acid-loving category.

Berry-Tone

by Espoma
4-3-2004
N-P-K
Sizes4, 27 lb
Price~$10-13 (4 lb)
IngredientsFeather meal, poultry manure, bone meal, alfalfa meal, greensand, sulfate of potash, sulfur; Bio-tone
OrganicOIM Registered

Holly-Tone

by Espoma
4-3-2004
N-P-K
Sizes4, 8, 18, 27, 36, 50 lb
Price~$8-12 (4 lb)
IngredientsSame as Berry-Tone formulation
OrganicOIM Registered

Acid Mix

by Down To Earth
4-3-2006
N-P-K
Sizes1, 5, 15, 25, 50 lb
Price~$15-18 (5 lb)
IngredientsCottonseed meal, fish bone meal, langbeinite, rock phosphate, kelp, humates
OrganicOMRI, CDFA

Happy Frog Acid Loving Plants

by FoxFarm
4-5-2003
N-P-K
Sizes4 lb
Price~$15-18 (4 lb)
IngredientsCottonseed meal, feather meal, bat guano, kelp, alfalfa, humic acid; mycorrhizal fungi
OrganicOMRI, CDFA

Natural Wonder Fruit Tree

by Dr. Earth
5-5-2002
N-P-K
Sizes1, 4, 12, 25 lb
Price~$15-18 (4 lb)
IngredientsFish bone meal, alfalfa meal, feather meal, potassium sulfate, kelp; TruBiotic + mycorrhizae
OrganicOMRI, CDFA, CCOF, NOP

Acid Lovers

by Dr. Earth
3-4-2003
N-P-K
Sizes1, 4 lb
Price~$20-25 (4 lb)
IngredientsCottonseed meal, fish bone meal, alfalfa meal, feather meal, potassium sulfate, kelp; TruBiotic
OrganicOMRI, CDFA, NOP

Berry Food

by True Organic
5-4-2004
N-P-K
Sizes4 lb
Price~$10-13 (4 lb)
IngredientsPoultry manure, seabird guano, fish bone meal, soybean meal, sulfate of potash, crab/shrimp shell
OrganicOMRI, CDFA, ISO 22000

Azalea, Camellia & Rhododendron

by Jobe's Organics
5-4-2003
N-P-K
Sizes4, 8 lb
Price~$10-13 (4 lb)
IngredientsBone meal, feather meal; Biozome
OrganicOMRI Listed

Berry Mix

by Fertrell
4-2-2004
N-P-K
Sizes5, 25, 50 lb
Price~$15-20 (5 lb)
IngredientsCalcium carbonate, peanut meal, feather meal, bone charcoal, blood meal, sulfate of potash, sulfur; boron, zinc
OrganicCertifiable organic

Holly Care

by Fertrell
4-6-2004
N-P-K
Sizes10, 25, 50 lb
Price~$20-25 (10 lb)
IngredientsFeather meal, calcium carbonate, blood meal, bone charcoal, zeolite, peanut meal, kelp, sulfur
OrganicCertifiable organic

🫐

Acid-Lover Base for Blueberries

NCO Pro-Holly is formulated for acid-loving species. Blueberries need pH 4.5–5.5 — this formula works within that acidic environment instead of fighting it.

🌸

6% Phosphorus for Flower Set

Higher phosphorus supports the flower bud development that determines next year's berry crop. More flower buds = more berries per bush.

🌿

Gentle on Fine Roots

Blueberry roots are extremely fine and fibrous — sensitive to salt burn from synthetic fertilizers. Slow-release organic nutrients feed without damaging the delicate root system.

📅

Spring + Fall Program

Spring application fuels bloom, fruit set, and berry sizing. Fall application supports root growth and builds the flower bud reserves for next year's crop.

Common Questions