How to stop cat pooing in garden.

[Karbea]

i inherited 3 Persian cats when I married my husband, last summer we moved house and so they were house cats for a long time, they are now back outside. 2 of the 3 have taken to pooing right outside the backdown under my whirligig washing line, so, whilst eating I watch them poo and whilst hanging out washing I either tread on it, or the wind blows stuff off the line and it lands on it.
They can easily poo elsewhere our garden is very open plan and their flap isn't in the back door so they have to walk to this place to poo.

I've been googling and possible options are lemons, cayenne pepper, plant lavender etc.

Anyone know what works?

Thanks!

Citrus smells put them off so lemon is a good option. I've also heard that you can buy pellets of lion poo from the zoo which puts them off because they can smell that it comes from a bigger cat. I haven't tried that myself but it's worth giving it a go.