I am here again a bit worried. Please help me identify what is the problem and how can I help my little plants. I successfully managed to grow the curry leaf plant from the seed in my greenhouse, but they were attacked by greenhouse thrips, so I chopped off the infected part and just left the stem and moved them into my conservatory, where I started treating them by spraying the Bayer Provado ultimate bug killer. After about 6-8 weeks in conservatory, I move them in my house as the temperature was dropping to 0-1 deg, and the heater in my conservatory is not working. Once I moved in them in house, I see good signs of the stems/leaf growing. I was happy so I watered them with Baby Bio and I saw little green tip of the stem grew and then it's all turned black and the main stem, which was all green up until now, has now started drying. I have made a horticultural oil at home (cottonseed oil + soap + water) and applied yesterday, assuming thrips are still there. But it has not affected the other plant in the same pot. Please see the pictures. Please, help me save them. What is wrong? Thank you for your help in advance.
Help, My Plant Is Dying
Certified GKH Gardening Expert
Cutting off a seedling's only leaves will almost always kill it, since it won't have enough energy to grow more. Focus on saving the remaining plant that has leaves, since the others won't grow back. I recommend removing the stem of the dying plant and discarding it so that it won't infect the healthy plant in the same pot.
Keep going with the horticultural oil and/or the Bayer product. Thrips sometimes walk around on the surface of soil, so you could try removing the surface layer of soil and replacing it with fresh soil. Also, to keep the plant healthy, make sure it is not overwatered and that there are enough drainage holes in the bottom to prevent salt buildup in the soil.