Soil Temperature & Soil Moisture Charts

Soil Temperature (F) Soil Conditions
Less than 20 Degrees

Deep Freeze - Winter Kill Possible

Less than 33 Degrees

Frost Line - Soil Frozen

Less than 50 Degrees

Too Cold To Plant - Root Growth Only

51 - 59 Degrees

Minimum Growth - Optimal Root Growth

60 - 75 Degrees

Optimal Shoot Growth

76 - 90 Degrees

Ideal Growth - Shoot Growth Only

Centibar Reading Soil Conditions
The centibar (cb) is an agricultural unit of soil water tension (water pressure on plant roots)
0-10 cb

Saturated Soil.  Occurs for a day or two after rain or irrigation.

11-30 cb

Soil is adequately wet (except coarse sands which are drying out at this range).

31-60 cb

Usual range to water (except heavy clay soils). Water at the upper end of this range in cool humid climates and with higher water-holding capacity.

61-100 cb

Usual range to irrigate heavy clay soils.

101-200 cb

Soil is becoming dangerously dry for maximum production.