My name is John from India and new to this forum as well as the Bonsai world. The temperature here is quite hotter throughout the year. I generally buy tree saplings from nurseries and pot it in a colander or a tray till it matures. Before transferring the plants from the plastic bag to the pot, I rake out the soil from the top gently and prune any downward or upward poking roots or stubs and thoroughly wash it before planting. As these are only available in India, my soil mixture is perlite, red soil, river sand, granite chips (1:1:1:2) and NPK 19:19:19 pellets. Unfortunately, the plants completely dry out and die after 2 days. One out of 5 plants survive generally and that would be a ficus. When I checked with the local nursery, they said that I should not rake out completely to transfer the plant as this method of exposing roots will not survive, but the soil comes with the plastic bag is a general clayey garden soil which cannot be used at all. I am not sure what mistake I am doing here whether it is the 19:19:19 NPK pellets or the exposure of roots.
I have attached the dried plants for your view (out of 3, only ficus in pink tray started to bud after the dried leaves have fallen).
Kindly advise on how to overcome this issue. Any ideas or suggestions would be really helpful for an amateur like me.