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Riley County

Lawn and Garden

Welcome to growing plants in Riley County.  We are blessed with many different growing conditions for you to express your gardening style.  There are deep soils along our water ways and shallow rocky soils on our hills.  Average rainfall is 4 inches different between North and South Riley County.

You are invited to bring in samples to the office of plants, insects, soil and diseases along with your questions for the Agent to assist you with.

 Horticulture>Project EverGreen is a nationwide outreach program connecting local lawn and landscape firms with men and women serving our country in the armed forces away from home.

Riley County Conditions

Historical Weather

Select the location you desire for information and the time span.

Weather Data Library

Access previous rainfall, soil temperature, and wind conditions for Manhattan

Average Last Spring Frost = April 18, May 9 is 95% frost free date

Average First Fall Frost= October 15

179 Growing Days

Average Rainfall in Manhattan = 34.8 inches

Average Rainfall for Riley County= 32.4 inches

Wildcat Creek Watershed

Soil pH range 3.8 – 10, average is 7.2,  most common 7.7,  6.5 is preferred

Cold Hardiness Zone 6a = -10° to - 5° F.

USDA Plant Cold Hardiness Map

Heat Zone 7= 60 - 90 days (average number of days per year above 85° F.)

American Horticulture Society Heat Hardiness Map