Separate lawn from hedge? How to do it visually nice and affordable?

Yes, very big was exaggerated... I meant big! Anyway... it was about something else ^^

What is it about?

There are also special lawn edgers that create a straighter edge than with the spade

We initially did it the way Karsten wrote, but the solution is not optimal... you wouldn’t think how wildly a lawn behaves and it’s hard to get close to a non-existent edge with the lawnmower... it’s like a man’s beard... try shaving it straight....

We now have these ~23 cm long stones that have a curve on one side and the matching groove on the other side... cost 50 cents per stone and you can also lay them well in a circle. (just google Mähkantenstein)

I like the English lawn edges best, that is the Nordlys model. Sharp cutting ... but it requires the most work when mowing and maintaining the edge.

The least work (when finished) is with the mowing edge, as described in #9. With a robotic mower, no work remains ... Then it still needs to be clarified how best to lay the stones. Simply on the ground? Or base layer and mortar bed? Who has what and in what condition for how many winters?

An intermediate solution are lawn edges made of (stainless) steel sheet, which are sunk vertically into the ground, maybe sticking out 1 cm. In my opinion, the edge must always be maintained here; manual mowing included.

Then it would still need to be clarified how to best lay the stones. Simply on the ground? Or base and mortar bed? Who has what and in what condition after how many winters?

We have laid such stones as a separation between lawn and flower bed. Simply on the ground, meaning flush buried. Simple, quick, cheap. Result after 5 years: Holds up, easy to mow over, but sooner or later the grass grows over the stones from the outside and a few blades like to come through the joints as well. That would certainly be different with a proper bed, but also much more laborious and expensive.