Submitted by Carol on

Forums: 

Some handy reference temperatures

Don't think you can get away with the 'minimum': At even a bit below 'preferred' temperatures, germination will take much longer and you are far more likely to lose your seedlings to slugs and other beasties.

Note that if the seed goes below the 'minimum' for even a few hours, germination will often stop. So cold at night can be a real problem.

Minimum (°C)

Preferred (°C)

Aubergine

16

24-32

Beetroot and chard

4

10-30

Broccoli, cabbage, cauliflower, kale & brussels

4

7-30

Broad beans

5

8-15

Carrot

4

7-30

Celery

4

15-21

Courgettes

16

21-35

Cucumber

16

16-35

French and runner beans

8-10

16-30

Lettuce

2

4-27

Onion

2

10-35

Parsley

4

10-30

Parsnip

2

10-21

Peas

4

4-24

Radish

4

7-32

Squashes and pumpkins

16

21-35

Sweet peppers and chillies

16

18-35

Sweetcorn

16

16-32

Swede

4

16-30

Tomatoes

10

16-30