How do tomato or lettuce seeds know when the temperature is right for germination? Well, this question will remain unanswered for now. We just know that it’s important that seeds have the right temperatures for germination. Germination temperature usually means soil temperature. During the day, soil stores heat. At night, soil releases heat into the atmosphere.
The University of Nebraska Video included below advocates for planting when soil temperatures are 10 degrees F (about 5 degrees C) above minimum germination temperatures. This concept is supported in our chart.
Seed Temperature Germination Chart
Source: Mostly from University of Oregon. Other information from other sources.
| Crop | Germination Minimum Soil Temperature (°F) | Germination Optimum Soil Temperature Range (°F) | Germination Maximum Soil Temperature (°F) | Days to Germination at Optimal Temps | |||
| Asparagus | 50 | 60-85 | 95 | 14-18 | |||
| Bean, lima | 60 | 75-85 | 85 | 4-10 | |||
| Bean, snap | 60 | 75-85 | 95 | 4-10 | |||
| Beet | 40 | 60-85 | 95 | 4-10 | |||
| Broccoli | 40 | 60-85 | 95 | 7-10 | |||
| Brussels sprouts | 40 | 60-85 | 95 | 3-10 | |||
| Cabbage | 40 | 60-85 | 95 | 5-10 | |||
| Carrot | 40 | 65-85 | 95 | 6 | |||
| Cauliflower | 40 | 65-85 | 95 | 4-10 | |||
| Celery | 40 | 60-70 | 95 | 10 | |||
| Chinese cabbage | 40 | 60-85 | 95 | 4-10 | |||
| Collards | 40 | 60-85 | 95 | 5-10 | |||
| Corn | 50 | 65-95 | 105 | 4-10 | |||
| Cucumber | 60 | 65-95 | 105 | 5-7 | |||
| Eggplant | 60 | 75-85 | 95 | 10-15 | |||
| Endive/Escarole | 35 | 60-75 | 85 | 10-14 | |||
| Garlic | 35 | 65-85 | 95 | 7-14 | |||
| Kale | 40 | 60-85 | 95 | 5-7 | |||
| Kohlrabi | 40 | 60-95 | 105 | 5-10 | |||
| Leeks | 35 | 65-85 | 95 | 8-16 | |||
| Lettuce | 35 | 60-75 | 85 | 2-10 | |||
| Muskmelon | 60 | 75-95 | 105 | 4-10 | |||
| Mustard | 35 | 60-75 | 85 | 4-6 | |||
| Okra | 60 | 85-95 | 105 | 7-12 | |||
| Onion | 35 | 65-85 | 95 | 4-12 | |||
| Parsley | 40 | 65-85 | 95 | 5-6 weeks | |||
| Parsnip | 35 | 65-75 | 85 | 5-28 | |||
| Pea | 40 | 65-75 | 85 | 5-7 | |||
| Pepper | 60 | 65-75 | 95 | 7-10 | |||
| Pumpkin | 60 | 85-95 | 105 | 4-10 | |||
| Radicchio | 35 | 60-75 | 85 | 5-7 | |||
| Radish | 40 | 65-85 | 95 | 4-10 | |||
| Spinach | 35 | 65-75 | 75 | 6-14 | |||
| Squash | 60 | 85-95 | 105 | 7-10 | |||
| Swiss chard | 40 | 65-85 | 95 | 7 | |||
| Tomato | 50 | 65-85 | 95 | 5-7 | |||
| Turnip | 40 | 60-95 | 105 | 3-10 | |||
| Watermelon | 60 | 70-95 | 105 | 4-10 |
Our dilemma of germination temperatures of tomato or lettuce seeds is answered, as well as for many other vegetable gemination temperatures.
