Measuring Soil Temperatures to Guide Seeding Timing

Monitoring soil temperatures prior to seeding will provide an excellent guide for timing the start of seeding.  Seeding into soils that are too cool can delay germination and result in uneven or unsatisfactory seedling emergence.

Measuring soil temperature can be accomplished with an inexpensive soil thermometer.  Here are the steps to follow to get accurate readings:

1. Determine how deep you will be seeding.  Place your soil thermometer at that targeted depth.
2. When using a probe-style thermometer, digging a small hole and inserting the thermometer horizontally at seed depth will ensure you are at the right depth.
3. Take two readings daily, one at 8:00 am and one at early evening.  Average the two readings to determine the average soil temperature.
4. Take readings for two to three days to establish a multiple day average. Measure in a number of locations in the field to account for field variability.
5. Soil temperature data is also available from MAFRD’s Ag-Weather Program:  http://tgs.gov.mb.ca/climate/SoilTemp.aspx (Conditions and Reports, Current Soil Temperature).  This will provide a general guideline for an area.

Minimum germination temperatures for various crops are:

Wheat 4C

Barley  3C

Oats  5C

Corn  10C

Canola  5C

Flax  9C

Sunflower  6C

Edible Beans  10C

Peas  4C

Soybeans  10C