Min/Opt/Max temps from IFAS
MINIMUM Soil Temperature for Germination
- 32° – Lettuce, Onion, and Spinach
- 40° – Beet, Broccoli, Cabbage, Carrot, Cauliflower, Parsley, Pea, Radish, Swiss Chard
- 50° – Sweet Corn, Tomato
- 60° – Lima bean, Snap Bean, Cucumber, Okra, and Pepper
- 65° – Squash
OPTIMUM Soil Temperature for Germination
- 70° – Celery, Parsnip, and Spinach
- 75° – Asparagus, Endive, Lettuce, and Pea
- 80° – Lima Bean, Carrot, Cauliflower, Onion, Radish, Tomato, Turnip
- 85° – Snap Bean, Beet, Broccoli, Cabbage, Parsley, Pepper, Sweet Corn, and Swiss Chard
- 95° – Cucumber, Okra, Squash
MAXIMUM Soil Temperature for Germination
- 75° – Lettuce and Spinach
- 85° – Lima Beans, and Pea
- 95° – Snap Bean, Beet, Broccoli, Cabbage, Carrot, Cauliflower, Eggplant, Onion, Parsley, Pepper, Radish, Swiss Chard, and Tomato
- 106° – Cucumber, Okra, Squash, Sweet Corn
About Southern Peas from Clemson.edu
Southern peas are a warm-season crop requiring warm soil temperature (at least 60 °F) for the best germination and emergence. Many pests and diseases will plague Southern peas planted into cool soils. Four to six seeds per foot of row should be planted three-quarters to 1½ inches deep in rows 20 to 42 inches apart.
From Harvest to Table.com
- VEGETABLE SEED GERMINATION SPECIAL REQUIREMENTS
- SEED STARTING SPECIFIC CROPS
- VEGETABLE SEED GERMINATION TEMPERATURES – The extracted table is below. That info is also at UC Sacramento Cooperative Extension Service here.
| Crop | Min Temp F | Opt Temp | Max Temp | Days to Germ. at Opt temp |
|---|---|---|---|---|
| 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 |
| Kale | 40 | 60-85 | 95 | 5-7 |
| Kohlrabi | 40 | 60-95 | 105 | 5-10 |
| 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 |
| 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 |
Fall Germination vs. Soil Temps from Johnny’s Seeds
The dates in the table below were produced by a spreadsheet calculator from Johnny’s Seeds website. The calculator determines planting dates for crops to be planted outside, without additional protection, for fall harvest. All are crops that are frost-tolerant and taste great in cooler weather.
The calculator uses this formula:
Number of Days to Maturity (they used varieties recommended for fall/winter)
+ Days of Average Harvest Period
+ Fall Factor (takes into account the slowing of growth that results from cool weather and short days in fall, amounting to about 2 weeks)
= Days to Count Back from First Frost Date
The Optimum and Maximum Temperatures came from the page at this site that cites the data sources.
| Based on the average first frost date of 11/30/2019 | |||
| Crop | Plant NLT ** | Opt Soil Temp | Max Soil Temp |
| Brussels Sprouts (TP)*** | 8/2/2019 | 65-85 | 95 |
| Cabbage, storage (TP) | 8/7/2019 | 85 | 95 |
| Leeks (TP) | 8/7/2019 | 75 | 95 |
| Cabbage, fresh eating (TP) | 9/1/2019 | 85 | 95 |
| Carrots (DS) | 9/5/2019 | 80 | 95 |
| Broccoli (TP) | 9/7/2019 | 85 | 95 |
| Cauliflower (TP) | 9/8/2019 | 80 | 95 |
| Onions (DS) | 9/11/2019 | 80 | 95 |
| Beets (DS) | 9/18/2019 | 85 | 95 |
| Greens, Asian, full size (DS) | 9/23/2019 | ||
| Lettuce, heads (DS) | 9/23/2019 | 75 | |
| Cabbage, Chinese (TP) | 9/24/2019 | 85 | 95 |
| Radish, Daikon (DS) | 9/26/2019 | 85 | |
| Swiss chard, bunching (DS) | 9/27/2019 | 85 | 95 |
| Lettuce, baby (DS) | 10/3/2019 | 75 | 85 |
| Spinach (DS) | 10/7/2019 | 70 | 75 |
| Radish, round (DS) | 10/25/2019 | 80 | 95 |
** The date calculated is the date to plant outdoors; crops that should be direct-sown are marked DS. Those marked TP should be set out as transplants on the date shown, so seeds should be started 4 weeks before the planting date.
*** Brussels sprouts should mature after frost, so no additional time is added for the harvest period or fall factor.
