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For decades, Specialty Soils growing media and custom blends have found their way into gardens, nurseries, botanical collections, university research and professional growing programs throughout the Pacific Northwest.
This archive brings together independent press coverage, horticultural references, published research and historical records that help tell the Specialty Soils story.
A Seattle Times profile of landscape designer Richard Hartlage’s garden discusses the custom Specialty Soils potting mix he uses for container plantings.
You can ask for the mix Richard Hartlage ordersRichard Hartlage, quoted by The Seattle Times
Published recipes, grower resources and independent gardening references document Specialty Soils media in professional and regional horticulture.
The Miller Garden published its container-soil formulation for woody plants and perennials and identified Specialty Soils as a source where the mix could be specially prepared.
The published recipe says plants can generally remain in the mix for three to five years.
SnoValley Tilth’s 2023 Agricultural Resource Guide lists Specialty Soils among regional agricultural suppliers.
Organic Seedling Mix is an SVT member favorite.SnoValley Tilth, 2023 Agricultural Resource Guide
The association’s cultural notes include Specialty Soils Growers Mix in growing-media guidance and document its component proportions for growers.
Pacific Northwest gardener Linda Cochran wrote about using Specialty Soils Aloe Mix for cactus, agaves and other dryland plants, and noted the company’s role supplying local growers.
Specialty Soils growing media and custom formulations have been used as research materials in university, federal and peer-reviewed horticultural studies involving nursery production, forest species and plant disease. The scientists conducted the research; Specialty Soils supplied or prepared growing media identified in their methods.
In a peer-reviewed Plant Disease study, researchers transplanted fir seedlings into a custom conifer potting mix prepared by Specialty Soils in Covington, Washington. The formulation is documented as part of the study methodology.
The historical research formulation included sphagnum peat, pumice, nitrified alder sawdust, aged fine bark, mineral nutrients, micronutrients, mycorrhizae and a wetting agent. This is a record of the study method, not a current commercial recipe.
USDA Forest Service proceedings describing Douglas-fir nursery research identify Specialty Soils Gardener’s Professional Secret as the growing medium used in the experiment.
A peer-reviewed Plant Disease study examining Phytophthora associated with Abies in U.S. Christmas tree farms identifies Gardener’s Professional Secret from Specialty Soils, Covington, Washington, as the commercially available growing medium used in experimental work.
A 2025 peer-reviewed Plant Disease study involving Turkish fir and Phytophthora identifies Gardener’s Professional Secret as growing medium used in the experimental system.
Washington State University doctoral research investigating Fusarium in Douglas-fir nursery production identifies Specialty Soils growing media in its experimental methodology.
University of Washington green-technology work examining lightweight growing media references Specialty Soils in Covington as a local provider and records Specialty Soils information used to evaluate lightweight mixes and costs.
The project page identifies a Specialty Soils price quote and references Chuck Nichols at Specialty Soils.
Historical public records and industry studies provide carefully sourced glimpses of Specialty Soils’ earlier years in Covington and Kent.
A 2003 King County study records an interview with Specialty Soils and describes the company as supplying nurseries, landscapers and other end users.
The report recorded Specialty Soils purchasing approximately 15,000 cubic yards of peat annually at the time—an archival snapshot of the scale of the growing-media operation more than two decades ago.
Historical public records associate the Specialty Soils name with the operation at 27525 Covington Way SE before the company’s current 1996-era history.
These records do not establish a corporate founding date and do not change Specialty Soils’ established “Quality First Since 1996” company history.
Archive records can document a name, location or business activity without establishing a corporate founding date. Specialty Soils continues to use its verified “Quality First Since 1996” company history.
From professional gardens to peer-reviewed research, Specialty Soils growing media have supported growers, horticulturists and researchers across the Pacific Northwest for decades.
