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Germination Temperatures and Times

We get a lot of questions about why your seedlings didn't sprout.  All vegetables are different and sprout in different conditions.  Some sprout in early spring in the cold, others in the middle of the summer when it's hot.  For this reason, not everything will sprout in your home in a window sill.  For some it is too warm, for others it is too cold.  This chart will help you determine what temperature is optimal for various vegetables, and also how long you can expect it to take for your seeds to germinate at a given temperature.  It isn't fool proof, however.  They planted all their seeds at 1/2 inch deep, which is too deep for most vegetables.  From personal experience, lettuce germinates best a little cooler than they state.  But it is useful as a guide, especially for the times to germination at various temperatures.  

Soil Temperature Conditions for Vegetable Seed Germination (in Degrees F)

Vegetable              Minimum Optimum Range
Optimum Maximum
Asparagus 50 60-85 75 95
Bean 60 60-85 80 95
Beet 40 50-85 85 95
Cabbage 40 45-95 85 100
Carrot 40 45-85 80 95
Cauliflower 40 45-85 80 100
Corn 50 60-95 95 105
Cucumber 60 60-95 95 105
Eggplant 60 75-90 85 95
Lettuce 35 40-80 75 95
Muskmelon 60 75-95 90 100
Onion 35 50-95 75 95
Parsley 35 50-85 75 90
Parsnip 35 50-70 65 85
Pea 40 40-75 75 85
Pepper 60 65-95 85 95
Radish 40 45-90 85 95
Spinach 35 45-75 70 85
Squash 60 70-95 95 100
Swiss Chard 40 50-85 85 95
Tomato 50 60-85 85 95
Turnip 40 60-105 85 105
Watermelon 60 70-95 95 105

Data Compiled by J.F. Harrington, Dept of Vegetable Crops, University of CA at Davis

 

Days to Appearance of Seedlings at Various Soil Temperatures (seeds planted at 1/2 inch depth, temperatures in degrees F)

Vegetable 32 41 50 59 68 77 86 95 104
Asparagus x x 53 24 15 10 11 19 28
Bean x x x 16 11 8 6 6 x
Beet ... 42 17 10 6 5 4 4 ...
Cabbage ... ... 15 9 6 4 3 ... ...
Carrot x 51 17 10 7 6 6 8 x
Cauliflower ... ... 19 10 6 5 4 ... ...
Corn x x 22 12 7 4 4 3 x
Cucumber x x x 13 6 4 3 3 ...
Eggplant ... ... ... 13 8 5 ... ... ...
Lettuce 49 15 7 4 3 2 2 x x
Muskmelon ... ... ... ... 8 4 3 ... ...
Onion 135 31 13 7 5 4 4 12 x
Parlsey ... ... 29 17 14 13 12 ... ...
Parsnip 171 57 27 19 14 15 32 x x
Pea ... 36 13 9 7 6 6 ... ...
Pepper x x x 25 12 8 8 9 x
Radish ... 29 11 6 4 3 3 ... ...
Spinach 62 22 12 7 6 5 6 x x
Tomato x x 43 14 8 6 6 9 x
Turnip x x 5 3 2 1 1 1 2
Watermelon ... x ... ... 12 5 4 3 ...

X    little or no germination

...   not tested

Data Compiled by J.F. Harrington, Dept of Vegetable Crops, University of CA at Davis