A Matter of Degrees
- Describe the effects that temperature has on germination
- Measure soil temperature effectively
As we’ve mentioned before, seeds need just a few things to germinate and a specific temperature is one of those. Whether you’re starting seed by directly sowing it in the hoop house, raised planter, or backyard garden it’s imperative that you do so once the soil temperature is in the appropriate range.
Getting an accurate temperature of the soil is straightforward. But you need to make sure that you are taking readings from the appropriate level in the soil. Germination mats can be used to regulate the temperature of a seed starting medium when germinating seed. If the seeds are being started outside or in a high tunnel, it’s imperative that you take temperature readings from the proper soil depth.
For greens and other cool-season crops it’s best to take the temperature at a depth of 2” and for warm-season crops a depth of 4” is better.Knowing the optimal temperature for your seed crop and how to effectively measure it is half the battle.
Teach the Teacher
Tools & Materials
- Soil thermometer
- Paper and pencil
Introduction (10 minutes)
Begin the lesson with a brief overview of why soil temperature is important when starting seeds. Describe the type of thermometer you will be using and mention the alternative types. Test your thermometer for accuracy using a second one.
Activity (20 minutes)
Have the Students take temperature readings at various depths and in different locations. Compare readings from one raised planter to another and even soil outside if possible. Record the temperature readings and label each location.
Discussion (10 minutes)
Is the temperature sufficient for the seeds we are starting today? Which locations would work? Which ones would not? If not, how much does it need to increase? What affects the temperature of the soil indoors? Outdoors? Can we increase or decrease the soil temperature indoors? What about outdoors? How would we do that?
Assessment (5 minutes)
Use the following questions to assess the Students before and after the lesson. Tally the responses of the group in the Assessment Tracking Log for comparison:
- By a show of hands, how many of you have ever measured the soil temperature before? Why?
- Now that you understand the importance of temperature in the seed germination process, how many of you think you could figure out the proper time to start seeds on your own?
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