I have had 2 rosemary plants and both of them have died, but I other herbs grow fine for me.

I grow everything in coconut fibre, and I know it is not the best for draining water off but all of my plants, even my succulents love it. I do add quite a lot of perlite to it to make sure.

My rosemary plant now (I'm not 100% sure whether it's fully dead or not yet) has turned very brittle, the entire plant, and is slowly losing its green colour and turning brown. I trimmed quite a few stems back and some leaves, because the tops of the stems were all looking droopy (as though it was wilting), so I trimmed those off and trimmed back the worst of the leaves and stems, as I thought it would take more energy away from the plant.

It is in full sun all day (when we get sun in Britain) in the greenhouse and has recently been repotted. My sage is in the same conditions as the rosemary, has been repotted, and pruned, and it seems fine. Why am I having so much trouble with rosemary?

I have recently bought another one, which I'm hoping will do better (third time lucky, huh?).

Thanks.