Washington County Soil Data
Washington County, Missouri
USDA SSURGO / PHZMAvg pH
5.6
Texture
Silt Loam
Drainage
N/A
Organic Matter
15.0%
Hydrologic Group
N/A
Data Story
About Soil in Washington County, Missouri
Unique Acidic Profile in Washington
Washington County features a very acidic soil profile with a pH of 5.58, well below the national median of 6.5. Despite the lack of dominant taxonomic data, its acidity makes it unique among its eastern neighbors.
Light and Silt-Focused Mix
The composition is 50.2% silt and 11.7% clay, which is a relatively light mix for the state of Missouri. The 17.9% sand content helps maintain some structure within this silty environment, though compaction remains a risk.
Extraordinary Organic Matter Levels
This county stands out with an extraordinary 15.01% organic matter, nearly triple the state average. This richness is coupled with an available water capacity of 0.151 in/in, which is slightly below the state norm.
Nutrient-Rich Soil Foundations
Although specific drainage data is limited, the massive organic matter levels suggest a soil that is incredibly rich in natural nutrients. This composition often indicates historic forest or wetland influence on the land.
A Goldmine for Zone 6b Gardens
Located in hardiness zone 6b, this nutrient-dense soil is a goldmine for dedicated gardeners. Use lime to raise the pH and unlock the full potential of that massive organic reservoir for your vegetables.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Hydrologic group data not available.
Drainage Class
Drainage class data not available.
Soil Profile
Dominant texture: Silt Loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Acidic Soil Detected
Your county's average pH is 5.6. These products help balance soil pH for healthier grass.
Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Washington County have?
Washington County's soil is classified as Silt Loam. This indicates the relative proportions of sand, silt, and clay — 18% sand, 50% silt, and 12% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Washington County's soil acidic or alkaline?
Washington County's soil has a pH of 5.6, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Washington County?
Drainage class data is not currently available for Washington County.
What crops or plants grow well in Washington County's soil?
Based on Washington County's Silt Loam texture, pH of 5.6, and drainage class, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens.
What USDA soil order is found in Washington County?
The dominant USDA soil order for Washington County is not currently available in our dataset.
Soil & Planting Advisory: Washington County
Soil Verdict
Washington County is in USDA hardiness zone 6b, a moderate climate zone. where winter lows can reach -5°F. Freeze-thaw cycles are moderate; soil biology slows in winter but recovers reliably in spring, supporting a broad range of plants.
Planting Guidance
A wide plant palette is possible: deciduous trees, most shrubs, cool-season vegetables, and many perennials thrive here. Winter protection (mulch, burlap wraps) helps push the zone boundary for desired species. Always match plant selections to the specific microclimate of your property — low spots, slopes, and wind exposure can shift effective hardiness by half a zone.
Soil Implications
Moderate freeze-thaw cycles naturally aerate the soil but can also cause compaction in clay-heavy areas; annual core aeration is beneficial. Organic matter amendments decompose at a moderate pace — aim for 3-5% organic content for optimal fertility. When soil temperatures drop below freezing, microbial nitrogen cycling stops; spring fertilization is more effective than late-fall application.
Regional Context
Washington County closely matches the Missouri average hardiness conditions.
Planning your lawn? View lawn care data for Washington County on LawnByCounty.com →
Other Counties in Missouri
Soil data sourced from USDA SSURGO via Soil Data Access. Data is informational only and should not be used as a substitute for on-site soil testing. Contact your local NRCS office for site-specific soil information.