Help help help. I planted 8 of these grasses in June last year. All growing well till Feb this year when one died. A month later another one went. I went back to Kings Plant Barn to ask what was going on. They didnt have an answer so went back to their supplier whose only comment was that he had never seen it before. They replaced another plant which has also died now as well as another. The soil is well drained and I watered weekly during the summer. So out of eight plants, I have now had to replace four. The leaves start to curl inwards instead of being flat and they just get worse from there. Is it some disease they are getting. Your help would be much appreciated please.
Try cutting them back; they may regrow. They are generally insect and disease free but check for aphids or spider mites. Here is more:
https://www.gardeningknowhow.com/ornamental/foliage/lomandra/growing-lomandra-grass.htm