[loulac]

Originally Posted by rhines81

I've seen this chart before. It has some merit, but it is missing the test method, growing media type and moisture content, number of samples per test and the number of times the testing was repeated under the same conditions.

I just tried to help PlainJane by giving her plain information. Of course, one can go much deeper, U.S. universities have done valuable research on the subject, but their publications would be off-topic in this thread.


Let me give additional simple information :
http://sacmg.ucanr.edu/files/164220.pdf
SOIL TEMPERATURE CONDITIONS FOR VEGETABLE SEED GERMINATION
University of California . Nice charts

http://www.kdcomm.net/~tomato/Tomato/start.html :
“One can start your tomatoes beginning 6-8 weeks before setting them out in just about any type of container that can provide drainage. Just make sure to start with good seed and a sterile soil mix. I like to use a half-peat moss, half-vermiculite mix. Using a sterile mix will reduce the potential for soil borne disease problems.
Pre-moisten the mix slightly before planting. Plant seed about 1/4" (7mm) deep, cover with soil and water.
Seed should emerge in about 3-5 days at a temperature of 75-80F/24-27C degrees (min 50F/10C max 95F/35C). Optimum temperatures for growth are 65-80F/18-27C days and 60-65F/16-18C nights. During germination, place them on the top of a refrigerator near the back to act as a heating source. Wait till after the seeds have germinated to put them in light as some genotypes (or varieties) require dark for germination to occur.”
You will notice that soil temperature, not air temperature should be taken into account. Of course, you can bury a thermometer into the soil but burying the sensor of a thermostat will remain the safest way to control the heat”.

I suggest :
https://www.amazon.com/bayite-Fahren...TE4A1M8EFZK9EQ
Bayite AC 110V Fahrenheit Digital Temperature Controller 10A 1 Relay with Sensor Price: $17.90
The model was sold for years by Willhi. I’ve got some, they have been working perfectly for years.
Directions for use on youtube :
How to set up Willhi Wh 7016 temperature controller installation. DIY ...


All the best
Loulac