Do you use salt on the driveway?

tj

no

2 feet is very narrow for a bed, however good the conditions. Gravel might not be a bad idea. Or something tough and shade tolerant like Pachysandra or Liriope.

That narrow strip between the driveway and the fence sounds like a tough spot, especially with three pin oaks drinking up most of the water. I agree the roots and shade are probably doing more damage than anything you have tried so far. If the ditch lilies keep dying back, I would lean toward something really tough and dry-shade tolerant rather than fighting the oaks every season. A simple gravel path with a few hardy groundcover pockets might actually look tidy there and save you a lot of frustration.

Geranium maccrorrhizum is my go to for dry shade. If the area gets hot afternoon sun, try its relative, G. 'Karmina', very similar though slightly smaller and usually longer blooming.