Seed from spinach we've let run wild for a few generations in our garden - for mini or large consistent leaves.
 
Germination Temperature: 7℃ - 26℃ / 44℉ - 79℉
Minimum and Maximum Temperature: -7℃ - 26℃ / 19℉ - 79℉
Ideal Growing Temperature: 15℃ - 18℃ / 59℉ - 64℉
Days to Maturity: 30 - 75 days