St. Charles County Soil Data
St. Charles County, Missouri
USDA SSURGO / PHZMAvg pH
6.5
Texture
Silty clay loam
Drainage
Well drained
Organic Matter
2.3%
Hydrologic Group
C
Data Story
About Soil in St. Charles County, Missouri
Near-Perfect pH for Versatile Farming
St. Charles County features an average pH of 6.53, which sits precisely at the national median for optimal nutrient availability. These Entisols provide a young but productive foundation, achieving a total soil score of 70.9.
Mastering Silty Clay Loams
The dominant silty clay loam texture comes from a mix of 61.9% silt and 21.6% clay. This composition ensures a fine-textured soil that holds moisture better than the 16% sand component would suggest.
Steady Nutrients and Strong Hydration
With 2.34% organic matter, these soils are healthier than the national average but fall below the state’s high organic benchmark of 4.74%. The available water capacity of 0.194 in/in remains superior to the Missouri average of 0.183.
Well Drained for Diverse Use
The land is officially well drained, making it suitable for both intensive agriculture and residential construction. It belongs to hydrologic group C, meaning it has a slow rate of water transmission when thoroughly wet.
Garden Success in Zone 6b
Zone 6b allows for a long growing season that supports everything from leafy greens to fruit trees. These well-drained silty soils provide a perfect environment for gardeners to maximize their harvest.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group C — Moderate-High Runoff
Soils with slow infiltration rates, often with a layer that impedes downward water movement. Higher clay content restricts drainage.
Drainage Class
Well drained
Water is removed from the soil readily but not rapidly. Optimal for most plants and construction.
Soil Profile
Dominant texture: Silty clay loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Clay Soil Detected
Clay soils can struggle with drainage. These products improve soil structure and water flow.
Browse Soil AmendmentsFrequently Asked Questions
What type of soil does St. Charles County have?
St. Charles County's soil is classified as Silty clay loam. This indicates the relative proportions of sand, silt, and clay — 16% sand, 62% silt, and 22% clay. Loamy soils hold moisture well and support a wide range of plants.
Is St. Charles County's soil acidic or alkaline?
St. Charles County's soil has a pH of 6.5, which is near neutral. This range is ideal for most garden plants and field crops.
What is the drainage class for St. Charles County?
St. Charles County has a dominant drainage class of "Well drained." Well-drained soils allow excess water to move through quickly, reducing waterlogging risk and supporting most field and garden crops.
What crops or plants grow well in St. Charles County's soil?
Based on St. Charles County's Silty clay loam texture, pH of 6.5, and Well drained, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens, most annual and perennial crops.
What USDA soil order is found in St. Charles County?
St. Charles County's dominant soil order is Entisols. Entisols are recently formed soils with little to no horizon development. They are common on floodplains, steep slopes, and sandy deposits.
Soil & Planting Advisory: St. Charles County
Soil Verdict
St. Charles 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
St. Charles County closely matches the Missouri average hardiness conditions. The zone range of 6b-7a within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for St. Charles 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.