Homemade Cold Frame HELP!

[craiglockley]

I've set up a cold frame using a large polystyrene box covered with a large piece of glass. In it I placed my chilli seedlings and some small flower plants which shouldn't be planted out till after frosts.

The leaves of the flowers have become covered in white blotches and some have holes as do some of the chilli leaves.

The plants are all being well watered but for the first week, I didn't leave it open so there was no air. Could this be the cause?

[SarzWix]

It could be that condensation has dripped onto the leaves, and then the sun has shone through the glass and the plants have scorched? Water on the leaves magnifies the effects of the sun, so they're more likely to scorch.
But I'm not sure that the lack of air will have done them any favours either!

[Gwyndy]

You do need to ventilate a cold frame. I am now leaving mine open an inch or so at night and opening the top completely during the daytime when I am at the allotment. If I can't get down to the site at least the plants will be able to breathe.

[craiglockley]

Thanks for this. I'll be sure to leave the glass of during the day. Is the scorching something the plants can recover from?

[KellsSimon]

It depends how bad it is, but so long as they still have growing tips, new leaves will grow through and carry on doing the job leaves do. the holey ones will just look a bit messy but should still be doing their job just not where there are holes!
You could try resting something under one edge of the glass on one side, this will let in air and help an condensation to drain off to one side rather than dripping on to your plants.
best of luck
Simon

[Two_Sheds]

If the marks are white and slightly powdery, it's a fungus, caused by water on the leaves and no air-flow.

Scorch is kinda brown and crispy looking. No, the leaf won't recover, but the plant will.

As the others have said, you need to ventilate.