London (change)
Today 26°C / 17°C
Tomorrow 27°C / 18°C
4 messages
17/04/2013 at 15:33

Hi,

how exact does the temperature need to be to raise seeds? i have a load coming, and the temperatures vary slightly although most say keep them at 21-24c (room temp).

would a sunny windowsill (inside) do? the temperature seems to be higher (around 27c), and in sun through the window would be even more. is this too much? it doesnt it really matter that much as long as its sheltered and quite warm?

 

17/04/2013 at 15:45

it's all about soil temperature not air temperature and i think consistency matters a lot of seeds like 15-20 degrees before they burst into life. you can find out from the seed packet or google germination temperature for x where x is the seed you want to germinate.

with germination the germination rates form a bell curve over temperature so most seeds will germinate successfully in the range given on the packet and seeds will be slower to germinate outside that range if they germinate at all.  Not only that some seeds need a pattern of temperatures, some need a period of cold (so they think they just went through winter) before they are prepared to germinate. Investing in a soil thermometer could be a good investment especially for next year now your likely to have reasonable temperatures now the weather has broke, he says (while the wind howls and the rain pours)

17/04/2013 at 18:36

Germination temperature and other conditions should be stated on the packet, and you need to read them carefully.  Some (not many) need a temperature that is only to be found somewhere like an airing cupboard - some need light, some need darkness (so a good covering on top).

The best temperature for the germinated seedlings is something else. It needs to be in balance with the light level to stop leggy seedlings that flop. With more light you can have a warmer temperature, and vice versa. You will be surprised how much the light is reduced on windowsills. Your eyes will deceive you as they adjust rapidly, but try a light meter and you will be amazed. 

17/04/2013 at 18:56

Hi djjjuk

What seeds are they? Some are more sensitive than others.  Let us know what you're growing, we might have some experience to help?

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