Washington County Soil Data
Washington County, Wisconsin
USDA SSURGO / PHZMAvg pH
6.3
Texture
Silt loam
Drainage
Poorly drained
Organic Matter
5.2%
Hydrologic Group
B/D
Data Story
About Soil in Washington County, Wisconsin
Washington's Elite Mollisol Ground
Washington County boasts an impressive soil score of 82.8, driven by its nutrient-rich Mollisols. The average pH of 6.31 is very close to the national median of 6.5 and much higher than the Wisconsin average of 5.63. These 'prairie soils' are among the most naturally fertile in the world.
The Silt Loam Advantage
The county's soil is a silt loam consisting of 44.5% silt, 34.2% sand, and 15.7% clay. This specific ratio provides a perfect balance of drainage and water retention. It is easy to work with a spade yet firm enough to support robust root systems.
Strong Water Retention for Growth
The soil contains 5.24% organic matter, which is more than double the national average of 2.0%. Its available water capacity of 0.209 in/in sits above the state average of 0.204 in/in. This ensures that gardens remain resilient even during the hotter, drier weeks of summer.
Managing Poorly Drained Lowlands
Despite the high quality, these soils are often classified as poorly drained and fall into hydrologic group B/D. This means the water table can be high, and the ground may stay saturated after heavy rains. If you are building or farming, consider raised beds or drainage tile to manage excess moisture.
Prime Potential in Zone 5b
Hardiness zone 5b allows for a wide variety of crops, from sweet corn to heirloom tomatoes. The naturally high pH and rich Mollisol base make this a gardener's dream location. You can grow almost any temperate vegetable here with minimal amendments.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group B — Moderate Runoff
Moderately deep, moderately well-drained soils with moderate infiltration rates. Good balance of drainage and water retention.
Drainage Class
Poorly drained
Water is removed so slowly that the soil is wet at or near the surface much of the year. Drainage improvement usually needed.
Soil Profile
Dominant texture: Silt loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Soil Amendment Products
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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 — 34% sand, 44% silt, and 16% 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 6.3, 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?
Washington County has a dominant drainage class of "Poorly drained." Poorly drained soils retain water for extended periods, which can limit crop choices and may require tile drainage or raised beds.
What crops or plants grow well in Washington County's soil?
Based on Washington County's Silt loam texture, pH of 6.3, and Poorly drained, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens, rice, cranberries, and other water-tolerant species.
What USDA soil order is found in Washington County?
Washington County's dominant soil order is Mollisols. Mollisols are fertile, dark-colored soils that formed under grassland vegetation. They are among the most productive agricultural soils in the world.
Soil & Planting Advisory: Washington County
Soil Verdict
Washington County is in USDA hardiness zone 5b, a cold climate zone. where winter lows can reach -15°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 Wisconsin average hardiness conditions. The zone range of 5a-5b within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Washington County on LawnByCounty.com →
Other Counties in Wisconsin
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.