I ordered a Carex variety called Bowles Golden Sedge, which arrived in good condition. As soon as I planted it, it immediately started to die. I have it in a shaded area that gets dappled morning sun, in the ground, in a soil mix of 1 part peat, 1 part compost, 1 part Turface hard-fired clay, and 1 part native clay loam soil. The plant is in a raised bed and drains well, but it is also well watered with drip irrigation, and the soil is constantly moist. I also have mulch on top of the soil. I have read that this variety of Carex likes moist soil, so probably that is not the cause of the problem. Can someone tell me what might be going on here? I had another Bowles Golden fail to thrive here, so there is something very basic I am missing.

This is what it should look like: