It looks to me like the trench is lower the the surrounding area. Water will pool in the lowest areas. That is gravity at work.

It is but that’s how all edging is like, it needs to be lower than the grass so the rhizomes don’t creep into the other side. But it’s only mine that always floods up

If the water drains away when the rain stops I wouldn’t worry about it. Is the soil compacted? If so you could spike it. Puddles and rain go together. If anything I’d make the edge sharper and a little deeper. And I’d plant the bed up to lessen rain compaction and erosion.

FlorslFloral, Would you please explain whst you mean by ”plant the bed up?”

Is spike the same as aerating? Soil isn’t necessarily compacted but that strip is a slope, the other side of the fence is higher than it so maybe the water just gets stuck in the edge.

That strip used to have the zoysia grass but I removed it because of mowing inconveniences, too much shade from the fence and weed maintenace coming from the other side of the fence. So I was just going to lay small river stone there and call it a day. On the right of it as you can see here is my meadow garden so not sure how plantings would look there in that narrow strip. Do you know of anything that would look ok being there?

I don't understand why water flowing to a trench would be a problem. Water is supposed to flow to the trench. Then the flow from the trench is supposed to take it one way or another to a road or another drain. It seems you have the very definition of proper drainage.

Planting up is just a way of saying filling the beds with plants. At the moment it is completely bare. I’d just continue the same plant mix as you have in the adjacent bed. And I’d have a bit more height in that bed too. Maybe even a small tree to block the view of the house next door. At the moment it all looks very empty.

Spiking is going over the area pushing a fork in all over as deep as you can. So yes, same as aerating.

My confusion is with your reference to an adjacent bed. Is this the strip of rocks along the fence?

No, I’m talking about what Heruga refers to as his ”meadow garden”. I’d continue that planting right along the fence. At the moment it all looks rather empty and barren.