Seed Germination Temperatures

The effect of temperature on seed germination varies by species. The following table summarizes some useful data about the germination of different vegetable species under different temperatures.

The data presented can be used as a general guide, but there will always be exceptions.

In 2013, I had tomatoes germinate after two weeks of weather near 50ºF. One specific variety refused to grow until warmer temperatures were provided.

For the 2014 season,  I acquired a surplus lab-incubator so I could provide germinating seeds with specific temperatures. With the incubator set at 25C, the tomato variety "Tiny Tim" all sprouted within four days. Another variety is still sprouting at 17 days later, with the first appearing at 14 days.



Each table entry is in format of "percent(days)". Entries with 80-89% germination are highlighted in yellow. Entires with 90+% germination are highlighted in orange. Entries that appear to be the best in terms of germination rate and shortest times are highlighted with pink.

Crops32ºF41ºF50ºF59ºF68ºF77ºF86ºF95ºF104ºF
0C5C10C15C20C25C30C35C40C
Asparagus0061(53)80(24)88(15)95(10)79(12)37(19)0
Beans, lima00152(31)82(18)90(7)88(7)20
Beans, snap00197(16)90(11)97(8)47(6)39(6)0
Beets053(42)72(17)88(10)90(6)97(5)89(5)35(5)0
Cabbage02778(15)93(9)0(6)99(5)0(4)00
Carrots048(51)93(17)95(10)96(7)96(6)95(6)74(9)0
Cauliflower0058(20)60(10)0(6)63(5)45(5)00
Celery072(41)70(16)40(12)97(7)65000
Cucumber00095(13)99(6)99(4)99(3)99(3)49
Eggplant000021(13)53(8)60(5)00
Lettuce98(49)98(15)98(7)99(4)99(3)99(2)12(3)00
Muskmelon000038(8)94(4)90(3)00
Okra00074(27)89(17)92(13)88(7)85(6)35(7)
Onions90(136)98(31)98(13)98(7)99(5)97(4)91(4)73(13)2
Parsley0063(29)0(17)69(14)64(13)50(12)00
Parsnips82(172)87(57)79(27)85(19)89(14)77(15)51(32)10
Peas089(36)94(14)93(9)93(8)94(6)86(6)00
Peppers00170(25)96(13)98(8)95(8)70(9)0
Radish042(29)76(11)97(6)95(4)97(4)95(3)00
Spinach83(63)96(23)91(12)82(7)52(6)28(5)32(6)00
Sweet Corn0047(22)97(12)97(7)98(4)91(4)88(3)10
Tomatoes0082(43)98(14)98(8)97(6)83(6)46(9)0
Turnips 11479(5)98(3)99(2)100(1)99(1)99(1)88(3)
Watermelon0001794(12)90(5)92(4)96(3)0
* The above data was taken from a report published in the mid-1980's.  Author, affiliation, and publisher are not known. 
** The above table was derived from experimental data.  Certain logical inconsistencies exist due to crop failure or to bad batches of seed.  They do not interfere with the overall interpretation.
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