I'm a beginner at gardening. Last spring we planted some creeping phlox. There are six of them planted in a circle equidistant from a Lavender Twist Weeping Redbud tree. One of them is dying and the adjacent plants aren't looking great, but the others look healthy.
They are planted somewhat close to our house and don't get a huge amount of sun. The ground is a bit sloped and the dying plant is probably on the steepest portion and furthest downslope.
We have six more of the same phlox similarly surrounding another tree in another garden bed that gets more sun, and those all seem to be thriving.
I haven't noticed any obvious pests on the unhealthy plants.
What is causing this? Lack of sunlight? Competition for water from the tree's roots? Overwatering?
