Germination Temperatures for Vegetables
It is important to know the ideal temperature for the germination of vegetable seeds, so that the gardener can gauge the best time to start sowing seed. For every species of seed, there is an optimal soil temperature for germination, which is shown in the chart below.
At the optimal soil temperature for germination:
- the maximum number of seeds will germinate
- seeds will germinate in less time than at any other temperature
Once the seed has been sown:
- the seed must germinate as soon as possible. If the seed lies in soil without growing, it may be damaged by fungus, or eaten by pests.
- the seed must germinate uniformly, not in a stop/start way, as this may damage the seedling.
The soil temperature, not the air temperature, is the important factor. Soil temperature at seeding depth is what matters.
The soil at the top of the seedbed will warm up faster than the soil deeper down. So the shallower the seeds are sown, the earlier they will germinate (as long as there is enough water).
It is better to sow seeds a little late rather than too early.
In general, seeds should be sown at the beginning of the season, when outdoor temperatures are likely to rise rather than fall.
Most vegetable seeds will germinate well/more quickly at higher temperatures.
Germination Temperatures for Vegetables
 |
Minimum (°C) |
Preferred (°C) |
| bean - broad |
5 |
8 |
| bean – french & runner |
8-10 |
16-30 |
| beetroot |
4 |
10-30 |
| broccoli/calabrese |
4 |
7-35 |
| cabbage |
4 |
7-35 |
| carrot |
4 |
7-30 |
| cauliflower |
4 |
7-30 |
| celeriac |
10 |
15+ |
| celery |
4 |
15-21 |
| chilli |
18 |
21+ |
| courgette |
16 |
21-35 |
| cucumber |
16 |
16-35 |
| eggplant |
16 |
24-32 |
| kale |
5 |
8+ |
| leek |
7 |
12 |
| lettuce |
2 |
4-27 |
| Mange tout |
10 |
12-24 |
| marrow |
16 |
21-35 |
| onion |
2 |
10-35 |
| parsley |
4 |
10-30 |
| parsnip |
2 |
10-21 |
| pea |
4 |
4-24 |
| pepper |
16 |
18-35 |
| pumpkin |
16 |
21-32 |
| radish |
4 |
7-32 |
| spinach |
2 |
7-24 |
| sprout |
4 |
7-35 |
| squash |
16 |
21-35 |
| swede |
7 |
10+ |
| sweetcorn |
10 |
16-32 |
| tomato |
10 |
16-30 |
| turnip |
8 |
8+ |
Sowing vegetable seeds in the spring should not begin until the soil temperature at seeding depth reaches or exceeds the necessary minimum temperature for germination.
plant seed vegetable garden
There is so much wonderful information here! I also love the diary format you’ve used. When I mentioned keeping a garden diary in my blog a few days ago, I didn’t even think about mentioning to do it in blog format. Thanks for visiting my blog and keep up the great work on your own.
Comment by Melissa - February 28, 2008 9:49 am
Hi Melissa
Thanks for that generous comment! Hope you will keep visiting us -
TopVeg
Comment by TopVeg - February 28, 2008 9:56 am
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