Crop Germination – What Soil Temperatures are Needed?

Soil temperature drives germination and seedling emergence, so how cold is too cold?  What is your soil temperature at your targeted seeding depth….today? Finally, when should you be measuring the soil temperature?

The following are the minimum temperatures needed for germination to begin in various crops.  These values should be regarded as approximate, since germination depends on factors other than just temperature.  But, if soils are too cool, germination will be delayed and cause uneven or poor seedling emergence.


Crop Temperature     (°C)
Wheat 4
Barley 3
Oats 5
Corn 10
Canola 5
Flax 9
Sunflower 6
Edible Beans 10
Peas 4
Soybeans 10

Sources: North Dakota State University Extension Service, Alberta Agriculture & Rural Development and Canola Council of Canada

Getting an accurate measure on soil temperature

Determine how deep you will be seeding. Then place your soil thermometer at the targeted depth. Take two measurements throughout the day: one in the morning (8am) and one in the early evening (8pm).  Average the two readings to determine the average soil temperature. The recommendation is to take readings for two to three days to establish a multiple day average and to measure at a number of locations in the field, to account for field variability.

Still not sure and short on time?  See the soil temperature data for various locations across Manitoba from the MB Ag-Weather Program:  This can be used as a guideline for an area, but in-field measurements are going to tell you what is actually going on in your field!


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Seeding for Target Plant Stands, not lbs/ac

Seed can be an expensive input, but a poor crop stand can be lost profit.  To maximize your seed, still get the stand needed to optimize yield, start calculating the real seeding rate needed for the plant stand desired and not gauging seeding rate by lbs/ac or bu/ac.

The following are the standard recommendations for FINAL plant stand, not what you are putting in the ground. Germination, TKW and mortality are very important to use in the equation to determine actual seeds/ac to plant.  For example, if you assume your germination is 96% and its only 85% and conditions turn cold and wet (increasing mortality), you may have a lot thinner stand than you anticipated (which could mean a harder time controlling weeds).

                    Grain Crops                               Oilseed Crops                   Pulse Crops        
Barley Wheat Oat Corn Canola Sunflower Flax Peas Soybean Dry Bean*
Plants/ft2 22-25 23-28 18-23 7-14 37-56 7-9
 Plants/ac (1000s) 26-30 18-22 180-210 85-100
Mortality Rates (%) 10-15 10-15 10-15 10-15 20-60 10 40-50 5-15 5-10 5-10

*Navy Bean = pinto beans on lower end and navy bean require higher plant stands

Source:  Manitoba Agriculture, Canola Council of Canada, Flax Council of Canada, Ontario Ministry of Agriculture, Food and Rural Affairs

 Seeding Rate (lbs/ac) = target plant stand/ft2 x TKW (g) / % expected seed survival x 10                       

 e.g. FLAX Seeding Rate= 45 plants/ft2 x  5g (TKW) / ((88% germination x (1- 40% mortality)) X 10 = 43 lbs/ac

Other information

Wheat –,aiming-for-higher-wheat-yields.html

Using 1000 Kernel Weight for Calculating Seeding Rates –

Canola –

Optimizing Plant Establishment –


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Determining Final Plant Stands in Corn

The corn crop in Manitoba is now planted and corn is emerging quickly!  Over the next few weeks is when producers should be evaluating their final plant stands as plants emerge and develop through early leaf stages.

Did You Hit Your Plant Stand Target or Miss it? 

To determine plant population or stand, count the number of corn plants in a row length equal to 1/1000 acre. Multiply that number by 1000 to get the number of plants per acre.  Do this several times in a field to get a representative sample.

  • In a 30-inch row spacing, count the plants in a 17’4″ row.
  • 20-inch row spacing, count the plants in a 26’1″ row.
  • 22-inch row spacing, count the plants in a 23’8″ row.

Now compare the final plant populations achieved to what you intended to plant, i.e. calculate your attrition losses.  If losses range up to 10% or more, investigate the reasons.  Was germination impacted by cold, wet soils? Did insects like wireworms or cutworms impact final plant stands?  Identifying the cause(s) behind the losses is important.  It can help determine whether changes in your planting operation or agronomic decisions may improve the odds of good stand establishment in the future.

Also keep in mind that corn that initially emerges and develops uniformly through early leaf stages can take a turn for the worse around the three- to four-leaf stage if the plant is damaged by insect or disease prior to the successful development of nodal roots from the crown area of the plant.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist


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Managing Winter Wheat Fields with Variable Plant Stands

Reports coming in across Manitoba indicates winter wheat survival ranges from excellent to poor.  In talking with some agronomists, those fields that did not have adequate stubble (density and height) and therefore poor snow cover are faring the worse.  Seeding date also seems to be playing a role where the later seeded fields are also impacted by winterkill or injury.

What is an Optimum Plant Stand?  An optimum winter wheat plant stand consists of 20-30 plants per square foot. But there is good yield potential with a less than optimum plant stand.  Check out the following post on CropChatter “Winter Wheat Stand Assessments” at

What if I Have a Field with Small Patches of Poor Stands?  For fields with small patches of poor stands, the best option is to leave the field and focus on management strategies such as controlling broadleaf and grassy weeds in a weed control program, early application of nitrogen to encourage tillering, and increase disease scouting since weakened plants may be delayed in growth leading to increased risk of rust and fusarium head blight infection.

What if My Field Has Large Patches of Poor Stands?  If you have fields with larger patches with few or no plants, decisions become more difficult. The first option is to keep the field and adjust your management based on the thin stand. Farmers will have to make hard decisions on what further inputs to put into the crop. Fungicide applications for foliar disease and fusarium head blight may not pencil out at reduced yield potential.

To help manage the larger patches, a possible option may be to plant winter wheat into the larger gaps. Winter wheat planted in the spring will not vernalize so it will not produce a head. However, it will provide ground cover and compete with weeds until harvest.

For winter wheat fields whose stand is extremely variable with large patches of dead or weakened plants, replanting may become a more realistic option. If you are considering reseeding and before destroying any wheat fields, you will need to contact your local MASC insurance agent. For more information on winter wheat insurance information, please visit MASC’s website at:

There is also additional information on Crop Chatter if faced with re-seeding:

Submitted by:  Pam de Rocquigny, MAFRD Provincial Cereal Crops Specialist


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What is the Extent of Crop Damage From the Heavy May Rains?

Compiled by the Staff at Crop Industry Branch, Manitoba Agriculture

Some areas of Manitoba received heavy rainfall during the May 2013 long weekend, resulting in the question “What is the extent of crop damage from the heavy rains?”

Field by field assessments over the coming days will give us a better idea of what impact the rains had.  The following though can provide you with an idea of what is potentially occurring and how to monitor fields to assess for damage and recovery.

What is the Extent of Crop Damage from the Heavy Rains – Updated May 2016

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