What are the methods to turn weak seedlings into strong ones? Practical techniques for revitalizing them

Ways to make weak seedlings grow strong When I divided the pots this spring, I kept a weak old pseudobulb, and instead of discarding it at the time, I potted it separately and set it aside. Later I actually noticed a small growth point gradually emerging from the soil. At that point I gently covered the growth point with soil, and as the growth point kept growing over time, I gradually continued to cover it with soil from the pot, and in the end this shoot grew very strong. I do not understand the reason, but we often see that the vitality of small wild grasses or bamboo shoots is very tenacious. The more you gently cover them on top, the more they will ultimately have to poke their heads out. Perhaps this is what stimulates the plant's growth potential. http://www.dfac.cc/showtopic-17-232753-0-0-1.htm