Hi sarah, tomatoes grow roots from their stems below the first seed leaf. If they get leggy you can even plant them sideways so long as the first leaves are above the ground, and they will root. Amazing ain't it? If you think have slower growth, it may be the shock of transplanting, or the optical illusion of a bigger pot/smaller plant, or too wet? ::) Ignore them for a bit and see what happens. I have had to be away for a week at a time recently, and it's done my baby plants a power of good to be, erm, left alone :-[.