Answer:
Other factors could affect the reason the seed didn't germinate because under suitable conditions depending on the variety it should germinate within 5 to 10 days from planting. However, the most likely reason it didn't germinate must be the Temperature.
Step-by-step explanation:
From the question above, the farmer lives in Minnesota and she planted between March and May, meaning the temperature was way cold which is not suitable for tomato. One other valuable point was she planting outdoor which could also affect the performance of the tomato seedlings. Planting in early spring doesn't necessarily mean bad as some seeds might thrive under conditions explained above. For tomato, depending on temperature because too high temperatures could also affect the viability of the seeds. In Minnesota in early spring, it would have been better if she planted indoors to raise the temperature before transplanting as a balanced night temperature is also important for the seed viability.
Some other factors to be considered for seeds to germinate:
1. Water
2. Type of the soil
3. Seed depth in the soil
4. Nature of seed coat
5. Oxygen
6. Light