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Horticultural Vermiculite

Horticultural products


Our horticultural products are mined from nature and carefully processed for the professional grower and the home gardener.


Horticultural vermiculite has the excellent property of improving soil aeration while retaining the moisture and nutrients to feed roots, cuttings, and seeds for faster growth. In many horticultural applications, horticultural vermiculite is a critical component for the grower and the homeowner.


Vermiculite is the name given to a naturally occurring hydrated laminar mineral similar to mica. Once the vermiculite is processed (exfoliated) it is sterile, odorless, non-toxic, and permanent. It has desirable horticultural characteristics, such as being lightweight, with a high capacity for moisture retention. It also holds and releases nutrients (high cation exchange capacity  CEC).


The color of vermiculite can range from light tan to a golden brown depending on the size and origin. It has a bulk density of four to six pounds per cubic foot. Each grade size has a particular specialized application in the horticultural industry.

J.P. Austin / A-Tops Highest Quality Vermiculite Supplier since 1962

A-Tops Horticultural Vermiculite

J.P. Austin/A-Tops produces and packages three main grade sizes of horticultural vermiculite:   Medium (Grade 2), Coarse (Grade 3), and Extra Coarse (Grade 4).


Vermiculite for seed germination: 
Medium (Grade 2) is used primarily as a germination media - on its own or mixed with peat moss. Vermiculite germination seedlings tend to have dense root growth and establish quickly in the growth cycle.


Vermiculite for outdoor transplanting:
Course Vermiculite (Grade 3) is an excellent soil amendment for dense or heavy soils. It is common to use up to one half the total volume (by bulk) of vermiculite in soil to provide proper drainage and aeration. In sandy soil the vermiculite improves moisture and nutrient retention, causing quick growth soil penetration for plant roots systems.


Placing 2 to 3 inches of vermiculite around the base of shrubs and garden plants prevents drying out and provides insulation against temperature variations.


Vermiculite for root cuttings:
Course (Grade 3) and Medium (Grade 2) Vermiculite are excellent for rooting all types of cuttings.


Vermiculite for bulb and tuber storage:
The insulation and moisture control of vermiculite is an medium ideal for bulb and tuber storage. Pour 3 to 4 inches of vermiculite in a deep container then add bulbs or tubes and repeat layering the vermiculite between levels.

J.P. Austin / A-Tops Highest Quality Vermiculite Supplier since 1962
J.P. Austin / A-Tops Highest Quality Vermiculite Supplier since 1962

J.P. Austin / A-Tops                                      


     Highest Quality VERMICULITE Supplier                           since 1962.

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