Help planten gaan snel achteruit en weet niet waarom, of wat ik kan doen. Ze zijn 8 weken ouden 4e week in bloei

I have a plant whose buds have turned brown, and the plants have deteriorated a lot in the last week. When I give water, the leaves turn yellow; when I give nutrients, Plagron Bloom 2 ml and Green Sensation 1 ml per 1L of water, the tips of the leaves turn brown and there are burn spots on the leaves.