New to gardening - deadheading?

Those particular pelargoiums don't like to get their petals wet, so given the amount of rain we have had, that could be why they look a bit scruffy. When you water, aim at the compost and try to keep the leaves and flowers dry.

I find bark chip does get a bit slimy after a while with daily watering.

 

Interesting thanks.

ideally I want some easy to care for, colourful flowers that last a long time and aren’t very pollen-y (as I suffer very badly from hayfever).

 

Pelargoniums definitely last a long time. You could try some bedding fuchsias next yr. They need very little attention and flower till well into autumn. Some trail and some are upright. Lobelia are fairly easy too. And osteospermums, if you like daisy-type flowers. You can get these in all sorts of colours now, and they can even survive a mild winter.