Horticultural Perlites


Sil-Ponix is our brand of horticultural perlite commonly referred to as Krum. It is used as a nutrient carrier solution in a water-solvent-based growing medium. Ease of water and nutrient management, even moisture status around the roots, excellent air-water balancing, and consistently high yields have time and again established horticultural perlite as a key ingredient in any top performing growing medium.


Horticultural perlite has been successfully used in everything from potted plants to stadium turf. It is widely accepted as the superior choice in meeting the needs of commercial growers and home gardeners. Coarser particles absorb less water and promote better airflow. Finer particles absorb more water than coarser particles. At Silbrico, we develop Sil-Ponix in three different sizes so that the amount of moisture retained can be tailored for the particular use Sil-Ponix products and their main uses:

  • Medium: seedling growth
  • Coarse: Soil mix
  • Super Coarse: Hydroponics

Learn more about these in the Grades section below.


The surface of each granule is covered with tiny cavities. This physical structure makes Sil-Ponix an ideal growing medium, providing optimum air-water relationships for efficient plant growth. It is a naturally occurring mineral that is lightweight, easy to handle, and also permanent since it doesn’t decay or dissolve. Sil-Ponix is sterile, free of weeds and disease, and has a neutral pH of 6.5 to 7.5–the ideal zone for most plants to absorb nutrients.


Medium: Seedling Growth

Works perfectly for seed cultivation and propagation because it clings to roots, reduces transplant shock, and increases survival rates.

Coarse: Soil mix/Hydroponics

Promotes drainage and aeration in heavy soils and provides optimum moisture retention for successful plant growth in all types of soil.

Super Coarse: Hydroponics / Specialized Applications

Provides constant moisture status around the roots, irrespective of weather or stage of root growth. Also ensures more even watering and resists overwatering.

Chemical Analysis

SiO2Silicon Dioxide73%

Al2O3Aluminum Oxide17%

K20Potassium Oxide5%

Na20Sodium Oxide3%

CaOCalcium Oxide1%

Trace Elements1%

Physical Properties

Hydroscopic Moisture 0%

Surface pH 6.5-7.5

Color White

Fusion Point (°F) 2300

Fusion Point (°C) 1260

Trace Elements

Manganese < 0.3%
Sulfur < 0.2%
Titanium < 0.1%
Barium < 0.1%
Gallium < 0.05%
Boron < 0.01%
Chromium < 0.0075%
Zirconium < 0.003%
Molybdenum < 0.002%
Nickel < 0.002%
Copper < 0.0015%
Lead < 0.001%*
Arsenic < 0.001%
Chlorine < 0.0005%

All analyses are shown in elemental form even though the actual forms present are mixed glassy silicates. Free Silica may be present in small amounts, characteristic of the particular ore body.

*By Food Chemicals Codex Method

Comparative Properties of Growing Media
Commonly Used with Orchids

Perlite Bark Peat Rockwool
pH of Medium Neutral Slightly Acid Acid Slightly Alkali
Fertilizer Control Very Good Good Good Good
Leaching Very Easy Easy Fair Fair
Aeration Very Good Good Fair Fair
Disposal Easy Easy Easy Problem
Health Hazard Care Care Care Care
Sterility Yes No No Yes
Management Very Easy Fairly Easy Fairly Easy Fairly Easy
Simplicity Very Simple Fair Fair Fair
Weeding Very Easy Fairly Easy Fairly Easy Fairly Easy
Cost Competitive Varies Varies Varies
Ease of Potting Very Good Good Good Good
Repotting 2+ Years 1-2 Years 1-2 Years 1-2 Years
Nutrient Nil Minimum Minimum Nil
Overwatering No Yes Yes Yes
Re-wetting Easy Fair Fair Poor
Cation Exchange No Yes Yes No
Buffering No Slight Acid No

Perlite Benefits

  • Aerates and drains soil
  • Holds moisture and nutrients
  • Has strong capillary action
  • Promotes root growth
  • Prevents soil compaction
  • Clean, odorless and lightweight
  • Safe and easy to handle
  • Lightens heavy soil
  • Permanent and will not decay or dissolve
  • Less expensive than alternatives
  • Minimal setup and low maintenance
  • Available in various gradations


  • Potted plants
  • Hydroponic crops
  • Indoor gardens
  • Seed cover
  • Green roofs
  • Turf grass
  • Raised garden beds
  • Container planting
  • Lawns
  • Trees and shrubs
  • Bulb and tuber storage