Before the Spring Festival, I bought two clusters of orchid grass in the flower market, which is very dense, and although a few small buds have been produced for half a year, the leaves are not only not dense but sparse, but the reason is that the hair from the root of the leaves becomes black and dry

Before the Spring Festival, I bought two clusters of orchid grass in the flower market, which is very dense, although a few small buds have been raised for half a year, the leaves are not only not dense but sparse, the reason is that from the root of the leaf to black hair dry brown, to the end the whole leaf black brown dry death, do you know how to prevent it? Thank you Lanyou for your guidance