Adding gravel to a border

[BluePeterVag]

I’ve got a border that I’m trying to keep low maintenance. It currently has various box shapes in it, and it did have bark mulch but that has now rotted down. I would like to change from bark mulch to gravel. How easy is it to do? Would I need to put down weed fabric, and if so how is it best to cut the fabric around the plants?
The border looks like this, but without the gravel.

the good thing about bark mulch is that when it rots, it vanishes into the soil. pebbles just stay as pebbles but get scattered all over. And you need a lot to get a good depth.

you will definitely want a weed membrane to stop the pebbles getting mixed up with the earth. Get plenty so you can have big overlaps between the plants & cut in from the edges of each strip.

Thanks @parietal I might have to go back to bark mulch.