Cold/wind burn to leaves?

Hey all,
Yesterday morning, after a night of cold gusty wind during which the polytunnel doors got blown open, a few plants that were looking healthy the night before suddenly looked like this:


At first only a few plants had the white patches but as the day went on, more plants showed the same symptoms. On the younger plants, the older leaves are affected while the new growth is fine but on the more established plants only the tips and edges of the new growth is affected (like the last pic above).

All plants are in roughly the same soil mix (see sig for details) yet only about half the plants are affected, which is why I figure it's not a soil problem. I hope so anyway, if it's just cold then they'll get over it soon enough. I hate chasing deficiencies. Any ideas anyone? Peace, TEC.

Took some more pics this afternoon, it seems to have stabilised or at least isn't spreading as quickly as yesterday. Still a bit worrying though...

Maybe the cold slowed them down and they burned. This happens with me when I let the coco dry out too much between watering

Yeah they're usually pretty cosy in there at night what with the hot bed i've got going, but I think the door was open most of the night and while the temps didn't quite get to freezing outside, the wind would have been pretty bloody cold indeed. Actually, thinking about it, the plants that were sheltered behind the open door haven't been affected, but ones at the far end of the polytunnel from the open door are really bad but they're right in the path of the wind.

I feel a little bit more confident it's not some wierd deficiency now. Interesting that the same thing happens with too-dry coco.

In the unlikely event that you are correct...keep them warm, but here in reality treat as per nute burn and flush, 3 times the pot volume with air temperate ph neutral water, allow to recover in dim light one day or over nite.

Although the cold had pissed them off(see the red stems of the leaf) the real issue here has been the nute burn ..also look to see how dry the soil is, often serious wind will dry the surface out, avoid ripping of the leaves use them as a control point

Vostok, I hear what you're saying and I had wondered about nute burn but I've never had too much of a problem with it before and I'm feeding less than previous grows. I don't remember it ever coming on so quickly either, i mean there was literally no sign of anything the day before. The small ones have been in the soil a week now and the larger ones over 2 weeks. They've only had water since then and not much either - the soil holds water really well.

I dunno but it just doesn't make sense to me that they should be burnt now even stranger that it's old plants and new plants both showing signs but there are whole areas where plants are unaffected. I'm open to your suggestion so I'll flush one or two of the plants in pots and see if that helps, I'll have to be carefull not to do more damage by leaving them waterlogged though.

Oh, and they have about an inch of mulch on them, I checked as soon as I saw the white patches and the soil was perfectly moist underneath.

The issue is your soil..heavy loam based soil even without peat or moss will hold a lot of water, hence I advise growers to use a lot of perlite(20-30%) or sand or even gravel in their soils is to aid in root compaction and reduce the hot soil effects, true you did a good job ..but as above the wind got up the temp dropped, not that it worried the plants to much, but the wind dried out the leaves, the plant called out for more water and got it...along with considerable nutrition too...hence the burn...but dood I'm really gazing into my crystal ball here, ...but only cause I've done similar

I get it now man, thanks for spelling it out for me, it all makes sense.