Why are my salad box seedlings starting to shrivel and go brown?

I think you are right its a watering thing , water them either early in the morning or when suns going down also I think you need to increase watering a bit, can you put a tray under the pot and when you water any extra will sit in the tray and be soaked up as the container requires , for containers in the future you can buy some composts with water retaining gels in them and this will almost certainly help.

Sometimes with multi purpose composts that have dried out it is almost impossible to water the container properly as the water seems to run only between the walls of the container and edge of soil , if your container is getting to this stage then you need to sit it in water for a while to soak all the soil.

Personally (no offence intended) I would use John Innes no. 1 seed compost for seeds then replant on using multi compost. Seed compost has all the nutrients seeds need and the soil is much finer, allowing water to penetrate the tiny roots.

I agree with mac, water as soon as the compost appears dry.

lots of my seedlings were getting water on top and nothing underneath as theydry out, so I sat mine in a bowl of water for a few mins then put back on greenhouse shelves

seem to have perked up a bit too which is a bonus

x x

Also remember that seedlings don't really like sitting in full sun all day. Keep compost moist, but not wet, at all times. As another thought could a cat have peed on them?

I would think your seedlings are getting to much hot sun....but that's only a guess - follow the advice above and if that doesnt help, provide them with a little shade maybe?

Moongrower - cats dig a hole and pee into that - no sign of digging in that picuture ;-)

Sid don't bet on them digging a hole to pee - I've seen our mummy siamese intentionally pee on a plant to kill it - in all honesty I doubt this has happened with the seedlings but knowing they are perfectly capable of doing so...

I'm puzzled by the fact that the burnt off seedlings are just in the one spot which is where I got to wondering about a peeing cat.

I see your reasoning in that case Moon grower :-) Siamese are really funny cats - can't really compare them with others can you!

Hi Sid - no you can't the plant mum killed was a very large mecanopsis which we had growing for years. It had put out its new spring leaves but had not started growing upwards... little wretch took offense to and peed on several times when she thought I was not looking. Thankfully the rest of our mecs. are doing fine and she is not interested in.

Ummmmm - naughty puss-tat! Mine gets told off for stuff regularly - you're not alone lol

(By the way, I assume you meant 'mine' not 'mum'. I'm sure your mum does not go around peeing on your pot plants!!!! ha ha ha......x-D