Useful table of germination temperatures

Those of you who remember when summers were always sunny, and potatoes came in stones, will be able to convert Farrenheit to Centigrade, and be able to understand this. For the youth, 68 is the temperature of your living room when you are in need of a jumper, but not a coat. 32 is the temperature your shots come at, so you can't taste them, and 95 is almost body temperature. 

I lifted this table off the internet somewhere and I apologise to whoever put it there for not acknowledging them.  It indicates what temperature seeds germinate best at. It is important to note that seeds like tomatoes, cucumbers, etc, need a nice warm place and will not come up in a cold greenhouse in early spring. Likewise, some seeds such as those of lettuce and spinach, land cress and winter purslane will not germinate at high temperatures and need to be chilled for a while. 

Crops	32ºF	41ºF	50ºF	59ºF	68ºF	77ºF	86ºF	95ºF
Asparagus	0	0	61(53)	80(24)	88(15)	95(10)	79(12)	37(19)
Beans, lima	0	0	1	52(31)	82(18)	90(7)	88(7)	2
Beans, snap	0	0	1	97(16)	90(11)	97(8)	47(6)	39(6)
Beets	0	53(42)	72(17)	88(10)	90(6)	97(5)	89(5)	35(5)
Cabbage	0	27	78(15)	93(9)	0(6)	99(5)	0(4)	0
Carrots	0	48(51)	93(17)	95(10)	96(7)	96(6)	95(6)	74(9)
Cauliflower	0	0	58(20)	60(10)	0(6)	63(5)	45(5)	0
Celery	0	72(41)	70(16)	40(12)	97(7)	65	0	0
Cucumber	0	0	0	95(13)	99(6)	99(4)	99(3)	99(3)
Eggplant	0	0	0	0	21(13)	53(8)	60(5)	0
Lettuce	98(49)	98(15)	98(7)	99(4)	99(3)	99(2)	12(3)	0
Muskmelon	0	0	0	0	38(8)	94(4)	90(3)	0
Okra	0	0	0	74(27)	89(17)	92(13)	88(7)	85(6)
Onions	90(136)	98(31)	98(13)	98(7)	99(5)	97(4)	91(4)	73(13)
Parsley	0	0	63(29)	0(17)	69(14)	64(13)	50(12)	0
Parsnips	82(172)	87(57)	79(27)	85(19)	89(14)	77(15)	51(32)	1
Peas	0	89(36)	94(14)	93(9)	93(8)	94(6)	86(6)	0
Peppers	0	0	1	70(25)	96(13)	98(8)	95(8)	70(9)
Radish	0	42(29)	76(11)	97(6)	95(4)	97(4)	95(3)	0
Spinach	83(63)	96(23)	91(12)	82(7)	52(6)	28(5)	32(6)	0
Sweet Corn	0	0	47(22)	97(12)	97(7)	98(4)	91(4)	88(3)
Tomatoes	0	0	82(43)	98(14)	98(8)	97(6)	83(6)	46(9)
Turnips	1	14	79(5)	98(3)	99(2)	100(1)	99(1)	99(1)
Watermelon	0	0	0	17	94(12)	90(5)	92(4)	96(3)

The number in brackets is the number of days it took to reach this level of germination. So, as you can see in the picture, the tomatoes (on the left) are up before the peppers (on the right). I hope this helps.