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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Manitoba Ag Weather Network

Manitoba Agriculture has a number of weather stations across the province that measure air/soil temperature, soil moisture, wind direction and speed.  For local information please visit

Central/East/Interlake Regions:

Southwest/Northwest Regions:

Previous Day on Highs/Lows and Average Soil Temperature at:

Central/Easter/Interlake:  Southwest/Northwest:

Another useful application of the data gathered by the network for rainfall can be found at Rain Watch



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When Should I Start Planting Corn in 2017?

Is it better to plant into cold soils realizing the seed is going to sit there until the soil warms up? Or should corn be planted when soil temperatures are warmer and approaching 10°C?

Planting into cold soils.  Early planting is a component of successful corn production in Manitoba, to maximize yield, obtain high quality and low percent kernel moisture at harvest (which will decrease drying costs), and to ensure the crop is mature before fall frosts.

Cooler soil temperatures can delay the crop’s emergence. Wet conditions added to cold soil temperatures can favor soil pathogen development, increasing seedling disease risks in both germinating seeds and young seedlings. When planting early in the season or when the soil is cold, a planting rate 10% higher than the desired final stand should be considered to compensate for possible increased seedling mortality. As well, when planting into cool soils, other seeding management becomes important, such as good seedbed condition (good soil to seed contact) and planting operations (including planting depth).

For more complete information, visit Manitoba Corn Growers website at


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Is Manitoba’s Winter Wheat Crop Set Up to Survive Winter?

The most common question I receive over the winter months related to winter wheat production is “How is the cold weather/warm weather/lack of snow impacting my winter wheat?” Unfortunately, there are no easy answers over the winter months as we typically have to wait until spring when winter wheat breaks dormancy and stand establishment is known.

However, there can be a few key factors during fall establishment and weather conditions over the winter months that can provide guidance in terms of assessing weather and its impact to Manitoba’s winter wheat prior to the crop actively resuming growth next spring.

First step: record crop condition prior to winter. The crop stage and health/vigour of the crop as it heads into winter will provide an indication if the crop has a high chance of surviving the winter with minimal winterkill or winter injury. Ideally plants should be at the 3 leaf to 1 tiller stage and have well-developed crown tissue (and of course established into adequate standing stubble to ensure snow catch). And remember, the stage of crop development in the fall influences not only winter survival, but also yield potential, crop competitiveness, maturity and the risk of infection with diseases such as rust and fusarium head blight.

Second step: note the weather after seeding and prior to winter. Cool conditions in the fall where plants grow for 4 to 5 weeks, followed by 4 to 8 weeks (October to November) of growth that allow plant to acclimate and vernalize, is the ideal situation (relates back to an optimum seeding date of the first couple weeks of September). Read more about cold acclimation and vernalization here: Another key weather factor is open field conditions with little or no snow cover until freeze-up as this allows soil temperatures to gradually decline to freezing levels.

If your winter wheat crop and the fall weather met the above conditions, your crop is likely well-positioned to survive Manitoba’s winter.

Third step: record any weather stresses over the winter months. In the fall, winter wheat producers can take all the necessary steps to set their crop up to survive winter with minimal winterkill or injury. However, it is often the winter/early spring weather in Manitoba that can impact winter survival.  Producers should take notes of cold snaps (how long they lasted, when did they occur) and the snow cover during those events to gauge potential impact to their winter wheat crop.

Regardless of the amount of cold acclimation, we typically need to receive good snow cover to protect the crop from the sustained cold temperatures normally seen in January and February in Manitoba. The ideal situation would be a minimum of 4 inches of trapped snow cover through December to early March to buffer soil temperature changes and provide protection to the crown tissue.

To assist with recording any soil temperature stresses, there is real-time monitoring of soil temperatures in the four winter wheat fields across Manitoba (see The data will also be made available in the near future to the Winter Cereal Survival Model website at which can provide additional information on potential injury due to cold soil temperatures.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

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Monitoring Real-Time Soil Temperatures in Manitoba Winter Wheat Fields

Over the past three winters, Manitoba Agriculture through the AgWeather Program has been measuring soil temperatures real-time in winter wheat fields.  The monitoring of soil temperatures can provide an early indication if there is a concern for winter injury or winterkill.  The earlier a problem is identified or suspected, we are able to provide that information to industry so careful assessment of acres occurs in the spring.

There are 4 Manitoba Agriculture AgWeather Program weather stations measuring real time soil temperatures in winter wheat fields.  The sites are at Crystal City, Kleefeld, Oakburn and Virden.  Bookmark the link:

In the coming weeks, the data will also be made available to Western Ag for their Winter Cereal Survival Model, available at the following link:

I would highly recommend taking the time to read instructions on how to use the site and interpret the results.  Click here for instructions on how to use the model.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

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Fall Fertilizer Decisions Based on Soil Temperatures



Growers should be monitoring soil temperatures to guide fall nitrogen management.  Provincial weather station soil temperatures are posted at:

The principle of fall fertilization is generally to delay applications until soils have cooled so microbial activity is curtailed.  That way less of the stable ammonium form-N (NH4+,) that is held on clay and OM, is converted to nitrate (NO3-) which can leach or denitrify.

The rate of nitrification of banded N to nitrate is illustrated in the following table from


Table 1. Nitrification rates of ammonia to nitrate form-N from banded urea (calculated from Tiessen et al, 20031).

Average soil temperature at band depth Days for 50% conversion to nitrate Days for 100% conversion to nitrate
1 oC

5 oC

10 oC

15 oC

20 oC












So as soils cool and eventually freeze, the microbial activity is reduced such that ammonium-N is retained in its stable form.  If one chooses to apply nitrogen before Mother Nature provides cool soil – they may consider using one of several enhanced efficiency fertilizers – N-Serve, eNtrench, ESN or SuperU. 

Submitted by: John Heard, Soil Fertility Specialist

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Did my early seeded wheat survive this latest cold snap?

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

In my position, I talk with with numerous agronomists (both public & private) regarding cereal crop production.  Often issues facing Manitoba producers are issues facing producers to the east, west and south of us.

One such instance is Jochum Wiersma, who is the Cereal Specialist with the University of Minnesota, recently wrote an article on what the latest cold snap may have had on the earlier planted cereal crops in his area.  However, the information is truly applicable to conditions facing some acres here in Manitoba. Below is the article, along with the link to his blog post.

Did my earliest seeded wheat, barley, and oats survive this latest cold snap?

by Jochum Wiersma

The latest cold snap may have you wonder whether the earlier planted wheat and barley have a snowball’s chance in hell to produce a healthy seedling and stand?  Wheat, barley and oats do not germinate until the soil temperatures reach 40 F (4.4C).  The germination process starts with the uptake of water, breaking the dormancy and starting the development of the sprout.  Once the dormancy is broken the energy stored in the seed is used for the growth and development as well as respiration (basically maintenance).  If the temperatures are low or even freezing the growth and development of young seedling slows down or even stops.  However, respiration continues albeit at a lower rate and continues to deplete the energy stored in the seed.  This will eventually decrease the vigor of the seed and may prevent the sprouted seed to produce a healthy seedling.

With the freezing temperatures the first concerns is whether this can kill the sprouted seed.  Reports from the literature indicate that sprouted wheat and young seedling will likely survive temperatures in the low twenties (20F = -6.7C).  A quick first check of the color of radicle (first root) and coleoptile (first leaf) is the first step: a white and firm radicle and coleoptile will indicate that the sprout is not damaged by frost after the seed has been allowed to thaw out. A second test to determine viability of seed is to dig up seed and bring it home, place it between moist paper towels, and keep it at room temperature.  If the seed is viable the sprouts should start to grow within 24 hours.

Minnesota Crop News:

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Early Indications of Winter Wheat Survival in 2015

The ability of the winter wheat plant to survive the winter often depends on its ability to withstand low temperatures. Through the process of “cold acclimation” the plant acquires cold tolerance or winter hardiness. Factors that can impact the level of cold hardiness of the plant include weather, fertility, seeding date, and seeding depth.  For the 2014/15 winter wheat crop, majority of acres would likely be considered “well-hardened”.

Measuring Soil Temperature.  MAFRD has been measuring soil temperatures in four winter wheat fields throughout the 2014/15 winter (see CropChatter post  Plotting soil temperatures against various ‘hardiness” curves can provide an early indication if there is a concern for winter injury or winterkill.

The figure below illustrates the soil temperatures, measured at a 1″ depth, in four winter wheat fields across Manitoba, plotted against various ‘hardiness’ curves.

Figure 1: 2014/15 Soil Temperatures Measured at 1 Inch Depth in Four Winter Wheat Fields

2014.15 Soil Temperatures - Winter Wheat Fields

Data Source:  MAFRD AgWeather Program

Since majority of winter wheat acres are considered “well-hardened” and soil temperatures didn’t reach levels that went below the “high hardiness’ curve, winterkill isn’t expected to be a large concern.  However, since soil temperatures at one location did dip below the “mid hardiness’ curve, or at some locations got close to that curve, some areas within fields may be impacted.

Early Assessment of Growth.  From early reports of producers and agronomists bringing in winter wheat plants from the field or conducting the ‘bag test’ to assess winter survival, regrowth has been noted which is also good news. Continued scouting is encouraged though as fields start to break dormancy and growth resumes with earnest.

So between early assessments and the measured soil temperatures, winter wheat survival looks promising to date.  Keep in mind these early indicators shouldn’t stop you from assessing your own winter wheat fields though. As well, the weather in the coming weeks will play a large role in telling the final story of winter wheat’s survival.

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


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