How do we know as gardeners when the appropriate time is to plant those seeds or transplant our seedlings? There are guidelines on the backs of seed packets and tables and charts online and in books that tell us the supposed correct date to plant those seeds. But this generic information is usually based on the average last frost date for our area. If you’re in an area that doesn’t often get a frost or if you live in a frozen tundra that date can be deceiving. Plus, that information doesn’t take into consideration the fluctuations we see in our temperatures and weather patterns each season or the ever-changing climate. In nature, seeds just know when to sprout at the right time based on the cycling of the seasons. There proper germination is based on factors like moisture levels, light availability and, most importantly, soil temperature.
Today we’ll talk about optimal soil temperatures for both cool season and warm season crops, for both seed germination and transplant growth, how that compares to our average air temperatures, how to properly test your soil temperature and where to find historic soil temperature data for your area so you can more effectively plan your planting dates. Let’s dig in.