calibrachoa

First time I’ve tried these this year. I’ve had 5 from 3 different sources and they’ve slowly died off. First 2 from B&M in hanging baskets. The stems seemed to get bent, then that stem would die off, till they’d all gone. Replaced one with one from the range, that did brilliantly and then it went the same way.
Then these 2 in identical pots, right near each other from a local carboot.

Till last week, they both looked as good as the one on the left. In compost, watered daily, have never dried out, miracle grow once a week, what more do they want?!
Then the one on the right started exactly the same as the rest.

I thought perhaps the crown was getting too hot, hence the pile of compost there.
No drainage problems. Any tips to avoid losing this one too? Thanks
And here’s what they should look like, just to prove I don’t kill everything I touch!

 

Well, it’s a gonner by tonight. A bit of googling and it seems they’re susceptible to root rot and like to dry out a bit. I can believe that of the latest one in the pot, but not the hanging baskets-too dry if anything in those! I’ll let the remaining one dry out a bit though...