When a Bird of Paradise plant's leaves turn brown, curl, or stop growing, it's usually a sign of stress, often caused by improper care. Overwatering is a common issue, as this plant doesn't like wet feet, so if the soil is consistently waterlogged, the roots can rot, leading to brown leaves. On the other hand, underwatering can also cause problems, as the plant needs consistent moisture to thrive. Light and humidity can also play a role, as Bird of Paradise plants prefer bright, indirect light and a relatively high humidity, so if it's placed in a dry, dark spot, it may struggle.