PVC Greenhouses & 'Growing Hard'

[Ouya Mellsa]

I've always felt that seedlings growing in a PVC greenhouse (of whatever size/quality) are essentially grown 'hard' i.e. as if they were sown directly outside.

Yeah, they offer a mild amount of protection at night- by a few degrees at most- but they give less protection than the traditional 'hardening off' kit such as a cold frame.

Therefore, do you agree with me that most young plants grown in a PVC greenhouse do not need as much 'hardening off' as those grown in a GLASShouse?

[Two_Sheds]

... possibly, but they do protect from the wind, which is one of the reasons that you harden off - it's not just the temp

[Ouya Mellsa]

Sure, but in this good weather we are having the young plants should settle in ok. The nights are still chilly, but May is almost here so they should be up to a decent temp soon.

[SarzWix]

They'll only settle in okay, if they've been exposed to 'the outside' for enough time to toughen up their foliage. If they've been protected from the wind, the foliage will still be 'soft' and therefore they will suffer a set-back, regardless of what type of greenhouse they were raised in. Incidentally, a 'glasshouse' only gives a couple of degrees of protection too.
If you're desperate to plant out, and haven't hardened off for long enough, try putting a cloche over the plants?

[Ouya Mellsa]

I recall sowing tomatoes in a PVC greenhouse on Feb 14th a few years ago. They produced the best crop I've ever had.

I always harden off correctly, but this was just a theory I've always had.

[SarzWix]

I suspect it depends on the positioning of the greenhouse/blowaway; how much the temperature drops overnight - whether there's residual heat in house-wall/concrete floor etc., and also how exposed to the wind when the door is open. Eg. I know my back-garden greenhouse (which is only 6x4) gets really cold overnight as it's away from any walls, but is very sheltered from the wind by trees.

[Ouya Mellsa]

Yep, mine is sheltered and away from any weather-based nuisance.

[Two_Sheds]

... possibly, but they do protect from the wind, which is one of the reasons that you harden off - it's not just the temp

I've just taken some pics to show you what I mean

wind burn | Flickr - Photo Sharing!

These French beans have been outside hardening off (9-5) for a week now. They've been enjoying radiant sunshine, but the high winds have been from the north & the east. Look at the damage on the leaves: they look scorched