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What Are the Grades of Peat Moss

Friday, October 05, 2018 | Jose Chen Lopez

Because peat moss is a natural product, there are degrees of variation and not all peat moss grades are adequate for a particular blend you will find on the market. 

Field grades of peat moss are screened, blended and processed to achieve specific physical properties for market grades and intended use. Market grades are based on coloration of the peat moss and the particle size passing through different mesh screen sizes (10, 20, 50 and 100 mesh screens). 

Some of the common market grades include black peat, coarse/chunk peat, horticulture grade, fine, forestry and so forth.

Here is a brief description of each:

Black peat 

Black peat is a very dense, fine particle peat moss that is highly decomposed. It is sometimes used for blocking substrates for starting vegetable seedlings, such as lettuce. 

It is usually blended with other types of peat depending on the type of crops grown. It is popular with mushroom producers for mushroom casing mixes. It is also used as a soil conditioner for consumer products and sold as peat humus.

Coarse/Chunk

Coarse/Chunk peat moss is the most fibrous, blonde chunky peat moss. Because of its medium water retention capacity and porous structure for high aeration, it is most often used for azalea, camellia, bulbs, orchid mixes and when a highly porous growing medium is needed for large containers.

Horticulture grade

Horticulture grade, also called medium/coarse grade peat moss, is the most popular, widely used grade of peat moss. It is a blended peat from H1-H3 grades and has a fibrous consistency that provides a high degree of water retention and air porosity to help promote plant root development. 

It is most often used for flowering plant and vegetable production in flats to larger pots and baskets, mushroom production and nursery container mixes.

Fine

Fine peat moss is a short-fiber peat moss that is specially processed for use in small cell propagation, seed germination, plug production, hydroseeding and construction of golf greens and tees. It is fine peat that is screened from H1-H3 grades of peat moss and is ideal for applications that require debris-free peat moss.

Forestry

Forestry peat moss is a medium-fiber peat moss that is specially processed for use in small cell propagation of forestry seedlings. It is peat that is screened from H1-H3 grades of fibrous peat moss and is free of sticks. 

"Raw sphagnum peat moss is graded using the Von Post scale"

In summary, sphagnum peat moss is suitable for a wide variety of growing needs. In determining the grade of peat moss to be used for the production of plants, a grower should select the grade based on the needs of the plant and the physical characteristics and particle size of the peat moss that match those needs. 

Choosing the correct grade of peat moss will help ensure that the plants to be grown have the best chance for success.

For more information, contact your Premier Tech Horticulture Grower Services Representative:

Ed Bloodnick Horticulture Director US-South East	JoAnn Peery Horticulture Specialist US-Central, Canada-Central	Lance Lawnson Horticulture Specialist US-West, Canada-West
Troy Buechel Horticulture Specialist US-North East	Susan Parent Horticulture Specialist Canada-East, US-New England	Jose Chen Lopez Horticulture Specialist Mexico, Latin & South America