Yellowing tomato leaves

[cornish crabber]

I planted out my tomato seedlings in my greenhouse last week. Today I noticed that 2 of the plants have yellowing leaves. These are new leaves near the top and both plants are Pink Brandywine (the only ones I have), while all the Floridity plants are fine. They have all been treated the same and are in Tomorite growbag compost which I have decanted into large pots.
Any idea why this is happening?

[Scarlet]

What has the temperature at night been with you? Where are you?
Toms don't like getting cold. It was too cold out for my toms last night.
Are you using fleece?
How big are they?

#a photo would help?

[nickdub]

Weather as Scarlet said, is most likely - also have a feel around in the compost to see if it may be too wet or too dry.

[Miss Mousetrousers]

As they are all in your g-house and been treated the same, are the Floridity with them or in a different area? If you had the door open and they were just behind it, could it have been a sneaky cold wind that got them? Could they have been subjected to more direct sunlight? As said, have a gentle furtle to see if their roots are ok because obviously nutrients aren't getting to the new leaves for some reason.

[Jungle Jane]

It was too cold for me last night I was really shivering had to put the heating on. A photo would help though,sometimes top leaves can get sunburnt. I wouldn’t touch the roots,there’s no need to go rooting around,what if you broke them,things could get worse before we even know what the problem is.

[Scarlet]

I had lots in the GH last night - stuff that I couldn't bring in was wrapped up in newspapers and old single sheets that fit my bench perfectly.

Unfortunately I didn't cover one tray that had a tender annual climber in it - 2 plants out of 4 were completely wilted this morning.

[Scarlet]

I wouldn’t touch the roots,there’s no need to go rooting around,what if you broke them,things could get worse before we even know what the problem is.

I wouldn't either! Leave them alone and wrap up for the rest of the nights where forecast is below 10.

I think some of the heritage plants can be a lot less forgiving that F1s if given poor conditions.
The temps in Cornwall tonight are below 10 - cover over with newspapers.

[cornish crabber]

Thanks for all your helpful replies.
I’m in the far west of Cornwall where we are usually 2 or 3 weeks ahead of the rest of the country.
I think the answer is a bit of over watering and cold nights affecting the one variety more than the other. Will use fleece for the next week or so and hope things improve.
Again, many thanks for your quick and helpful replies

[Scarlet]

Yes, they just need a coat on some nights my Grandmother always used to say "don't cast a clout till May is out" ...I'm in West wiltshire, a couple more weeks and my chillies will be out too!

[MarkPelican]

Even though your two or three weeks ahead of the rest of us, I think you're a little early permanently in the greenhouse. They can't be short of food. Any other symptoms associated with cold (e.g. blueing stems)?

[Miss Mousetrousers]

MT must apologize for suggesting a furtle around the roots, and I now think it's over-watering together with the cold temps. Maybe a little dilute sea-weed feed sprayed over the leaves might help or shall I get my gardening coat off?