A natural based fertilizer with a synergistic blend of plant biostimulant, humic acid, and mycorrhizae ideal for rapid plant establishment.

Bolster 4-4-4 plus Iron

BOLSTER GRANULAR 4-4-4 plus Iron provides a blend of organic nutrients, beneficial microbiology, bio-stimulants, iron and V.A. Mycorrhizae that improves all plantings. Carefully selected arbuscular mycorrhizal species can promote greater access of plant roots to soil nutrients and water. 3% chelated iron promotes greening and rapid root development and seaweed extract, humic acid, and compost-based microorganisms act as biostimulants that enhance root growth and improve overall plant health. 

Professional Grade 

Suståne products are derived from biologically stable humus-rich compost and contain both water soluble nitrogen (WSN) and slow release nitrogen (SRN), beneficial microbiology, and all 17 elements essential for plant photosynthesis. With a near-neutral pH, a low salt index and low ammonium nitrogen percentage, Suståne will not cause seedling stress or plant fertilizer “burn”. Suståne products increase soil cation exchange capacity (CEC) by supplying humates and stable organic matter. Suståne’s organic and blended natural fertilizers provide all soil types with additional buffering capacity, allowing for more consistent and productive growth.

Benefits of BOLSTER 4-4-4 plus Iron
  • Provides quick green up followed by six to eight weeks of even color and growth.

  • Strengthens plants tolerance against hot, dry conditions.

  • Improves buffering against changes in soil pH.

  • Increases the soil’s ability to suppress plant pathogens and soil contaminants.

  • Increases soil porosity and stability for greater root development and water holding capacity.

  • Contains beneficial V.A. Mycorrhizae - see below.

  • Contains Ascophyllum nodosum seaweed.

  • BOLSTER G is extremely safe and will not cause plant burn or discolor

  • Reduces transplant shock.

Vesicular Arbuscular Mycorrhizal Fungi

“V.A. Mycorrhizae” refers to the species of fungi that forms beneficial associations with most plant species. It is a “Facilitator” that brings nutrients to plant roots, exudes “Glomalin” to improve soil structure and actually fill up available entry sites along roots to inhibit pathogens from attacking. Mycorrhizal fungi are a critical component of healthy soils. It affects available soil nutrition, plant carbon transfer, and increases water and P utilization and the physical structure of the soil and the types of other organisms present in the soil. BOLSTER contains 3.52 propagules per gram of Suståne's proprietary blend of four different species of V.A. Mycorrhizae.

Applications and Rates*

General Guidelines for Garden, Nursery, and Landscape Applications

Plant Establishment 

  • Pre-plant: Broadcast and incorporate into top 4 in. (10 cm) of soil. 50 lb. per 1,000 ft2 or 2,200 lb. per acre or 25 kg per 100 m2.
  • Post-plant (45-60 days): Broadcast and water in 25 lb. per 1,000 ft2 or 1,100 lb. per acre or 12 kg per 100 m2.

For Containers

  • Low Rate: Recommended for salt sensitive species or when applied to heavy, silty clay loam soils or heavy potting substrates (total porosity less than 65%).
  • Medium Rate: Recommended for use on medium feeding species or when applied to medium, clay loam soils and most potting substrates (total porosity 65% to 80%).
  • High Rate:  Recommended for use on heavy feeding species or when applied to light, sandy soil or light, porous substrates (total porosity greater than 80%).

Container Mix Rates by Volume
  lb. per cubic yard  kg per cubic meter
Low Med High Low Med High
11 20 30 6.5 11.8 17.8
Container Topdressing Mix Rates in Grams
 Rate  Container Size      
5" STD 6" STD 1 GAL 2 GAL 3 GAL
Low   6 12 14 30 56
 Med 14 26 38 78 134
High 20 36 56 118 208
Item # 
BOLSTER Granular® 4-4-4 + 3Fe
Package Size Units / Pallets
(1.4 .mm - 0.6 mm) 
50-30-1375 (international)
25 lb. bags
50 lb. bags
22.7 kg bags 
80 bags / pallet
40 bags / pallet
44 bags / ISPM pallet 


Total Nitrogen (N) 4%
0.4% Ammoniacal Nitrogen
0.4% Other Water Soluble Nitrogen
3.2% Water Soluble Nitrogen*
Available Phosphate (P2O5) 4%
Soluble Potash (K2O) 4%
Calcium (Ca) 4%
Magnesium (Mg) 0.5%
Sulfur (S) 1%
Iron (Fe) 3%

Derived from aerobically composted turkey litter, feather meal, sulfate of potash and ferrous sulfate.
*3.2% slowly available nitrogen from aerobically composted turkey litter and feather meal.

Also contains non-plant food ingredients:

Humic Acid
(derived from leonardite and aerobically composted turkey litter)     
Seaweed Extract (Ascophyllum nodosum) 1%
Vesicular Arbuscular Mycorrhizae 1.75%
Guaranteed minimum 3.52 propagules per gram:
   Rhizophagus irregularis
   Rhizophagus clarus
   Septoglomus deserticola
   Claroideoglomus etunicatum

2.47 spores/g
0.35 spores/g
0.35 spores/g
0.35 spores/g

92.25% Total Fertilizer Ingredients