Planting & seeds
Will my seeds sprout at this soil temperature?
Minimum and ideal soil temperatures per crop, and how many days germination takes at each.
How this works
Push a soil thermometer 1 inch deep and read in the morning, two or three days running. Below the minimum, seed rots before it roots; near the ideal it sprouts at full speed.
Questions people ask
How do I measure soil temperature?
A probe thermometer two inches down, mid-morning, several days running. Sowing off one warm afternoon is how seed rots.
What happens if I sow too cold?
The seed sits and usually rots before it germinates. Beans and corn below 60F are the classic failure - the seed is still down there, it just never came up.
Is soil temperature the same as air temperature?
No, and that is the point. Soil lags well behind air in spring, which is why a warm week in March is not a signal to sow.