Cabbage Seeds - Problems!!

[freefolk]

Good Morning All, I have started sowing cabbage seeds this year for the first time, planting every 2 weeks so far. They are in an unheated room, temp between 52-58 degrees. They are near a south facing window, with silver foil behind to prevent "leaning". The issue is this: so far the first 2 sowings (5 and 19 Feb) have taken and are growing well for "Offenham 2","Langedijk4" and "Greyhound". However the "Golden Acre Primo 2" are starting to become withered and papery round the edges of some of the leaves! All sowings are in 6cm coir pots. Any thoughts, (too much/not enough water) or maybe just a bad batch of seeds (Mr Fothergills). Many thanks.

[Snoop Puss]

Unlikely to be the seeds post-germination, more likely the conditions. When did you sow the Golden Acre Primo 2? If it's on both dates, are the seedlings from both batches showing the same problems?

[HoneyChild]

Maybe the silver foil is the problem? I've read that can create heat spots.

[bikermike]

are you over-watering them?

In any event, it sounds like disease/mould sort of thing to me. Can you separate the affected ones?

[Thelma Sanders]

Is that variety in a draught, or in more bright sunlight than the others?

[Snoop Puss]

Here's another question: are you watering from above or from the bottom?

Plus, is it just the first pairs of seed leaves or other leaves too?

[freefolk]

Thanks for the comments so far, in response:
Both dates/batches sown show the problem. No others are affected.
All sowings are in individual coir pots.
They are all receiving the same amount of light, being sat back from the window (secondary glazed).
Watering from the top, as they are coir pots, first pair of leaves only seem affected.

[veggiechicken]

Seed leaves (the first 2) always shrivel and die off.
PS I hate coir pots, so difficult to control the watering.

[Snoop Puss]

Yes, agree with both VC's remarks.

Also, depending on the coir supplier, you might find it contains no nutrients. You might need to feed a bit earlier than you'd expect if that's the case.

[freefolk]

Thank you again for the kind words and advice. I am growing the remainder in modular trays, as ultimately coir pots take up too much room. I will see what happens. May lose a few but there we go. And it's the sort of afternoon in Hampshire where you could put seedlings out in the sun for an hour or two.....not that I have!