One of the tricks when transplanting tomatoes is to bury part of the stem each time you do it. It keeps the plant from getting spindly and helps insure a solid root system. One of the things I’ve been trying is growing the tomatoes in the pellet (Jiffy 7s) longer than first emergence of the true leaves, so that I could push out the point at which I can bury the stem.

The plants do not seem to have suffered from this treatment.