Japanese Onions

[northener]

Managed to get some Japanese onions which i was going to plant outside but while i was clearing the greenhouse today had a thought about putting them in the greenhouse. Anyone tried it?

[northener]

[PurpleHeather]

They are intended for out doors. Don't forget the greenhouse can actually get colder than the outside over winter.

It may be interesting to grow some in and some out to see the difference.

The biggest snag I can think of is that they will utilise space in the greenhouse when you need to fill it with new things in Spring.

[RobinOfTheHood]

Don't forget the greenhouse can actually get colder than the outside over winter.

How?

That's a new one on me.

I'm planning on putting my japanese onions in the ground before the end of the week, not sure why you'd want them in the greenhouse? They're hardy as.

Unless you have no ground ready, of course.

[northener]

The greenhouse is all prepared and weed free now the toms and chillies are out.  I was concerned about the frost. Think i'll try half and half.

[PurpleHeather]

Don't forget the greenhouse can actually get colder than the outside over winter.

How?

That's a new one on me.

ANSWER

According to the study I read, it is something called an 'inverse effect'.

The cold can get trapped inside whilst the temperature warms up outside.

This would make sense if for example it snowed, the snow would act as an insulation keeping the inside of the greenhouse cold.

Like a vacuum flask can keep things hot or cold.

[thifasmom]

Don't forget the greenhouse can actually get colder than the outside over winter.

How?

That's a new one on me.

ANSWER

According to the study I read, it is something called an 'inverse effect'.

The cold can get trapped inside whilst the temperature warms up outside.

This would make sense if for example it snowed, the snow would act as an insulation keeping the inside of the greenhouse cold.

Like a vacuum flask can keep things hot or cold.

so would it be adviseable to always leave a vent cracked open during the very cold months ???

[RobinOfTheHood]

Maybe if it's covered in snow so that no light/heat could get in, but if it's covered in snow how cold would it be outside anyway?

Sounds wrong to me.

Has anyone here actually measured temps inside and out, and found it colder in? I haven't.

As for the vent, I guess an automatic one would be the answer, but they cost money!  :)

[Bean_Queen]

Snow is an insulator; like a duvet - it wouldn't keep the greenhouse colder than the outside.
A thick layer of snow can actually protect plants in the ground, although you would think it would chill them.