So why know about the temperature of the soil. Soil temperatures are the factor that drives germination, blooming, composting, and a variety of other processes.
So what is soil temperature? Soil temperature is simply the measurement of the warmth in the soil. Ideal soil temperatures for planting most plants are 65 to 75 F. (18 to 24 C.). Nighttime and daytime soil temperatures are both important. When are soil temperatures taken? Soil temperatures are measured once soils are workable. The exact time will depend upon your USDA plant hardiness zone . In zones with higher numbers, the soil temperature will warm up quickly and earlier in the season. In zones that are lower, the soil temperature may take months to warm up as winter chill wears off.
Most people don’t know how to check soil temperature or what tools are used for taking accurate readings. Soil temperature gauges or thermometers are the common way to take the reading. There are special soil temperature gauges used by farmers and soil sample companies, but you can just use a soil thermometer. Check in the early morning for a good average. The night’s coolness is still mostly in the soil at this time.
Soil readings for seeds are done in 1 to 2 inches of soil. Sample at least 4 to 6 inches deep for transplants. Insert the thermometer to the hilt, or maximum depth, and hold it for a minute. Do this for three consecutive days. Determining soil temperatures for a compost bin is also done in the morning. The bin should maintain at least 60 F. (16 C.) bacteria and organisms to do their work.
The perfect temperature for planting varies dependent upon the variety of vegetable or fruit. Planting before it is time can reduce fruit set, stunt plant growth and prevent or reduce seed germination. Plants such as tomatoes, cucumbers, and snap peas benefit from soils at least 60 F (16 C.). Sweet corn, lima beans and some greens need 65 degrees F. (18 C.) Warmer temperatures into the 70s (20s C.) are required for watermelon, peppers , squash , and at the higher end, okra, cantaloupe and sweet potatoes .
Here is the chart I had earlier. So we can plant the 40 degree seeds....if the soil is ready and not too wet.
Practical soil temperature for planting
40 degrees 50 degrees 60 degrees 70 degrees
Beets Turnip Cucumbers Cantaloupe
Carrots Cabbage Peppers Squash
Lettuce Swiss chard tomatoes Beans
Parsley corn watermelon
spinach carrot Eggplant
taken from URL to article: http://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/determining-soil-temperature.htm
This will give you some idea of what the soil temperature should be no matter what the calendar says. When all is ready, then it is time to plant. Be patient by dear friend, I promise you spring is here but now have to wait for all to warm up. Till next time, Becky Litterer from Becky's Greenhouse, Dougherty, Iowa