Sweet peas, whats wrong

Some of my sweet peas have the tips not flowering, like withered looking.
Is it a bug or something else? They are all in the same position and similar tubs.

 

Hi,

They look healthy plants other than those tips which I wonder if they are sun scorched in this very hot weather, though low down to the others, if they were watered from the top of the plant that or any fertilizer burn could have been the cause .

Also what about slugs or similar, could they have nibbled the tender tips, even mice or birds ?

Looking at your flowering ones, there are several large seed pods on them, do cut them off as soon as otherwise the plant thinks they have done their job and will die off, eg you will see some stems turn light brown and dead.

You really need to dead head / pick them for the house on a daily basis.

Also don't forget they need as much water and feed as you can throw at them in this weather.

 

I have since dead headed them, kind of got delayed with that ritual as I was taking advantage of the good weather and built a garden bench (small shed so have to do outdoors) Slugs have been non existent this year so not that. Maybe birds but not consistent when the other 3 are ok.
They have been watered fed as per the ones that look ok (at soil level)

I think there is something else at play.