My N. ventrata has grown quite a bit(its now been in my care for a little over a year). Its around maybe 7 inches "tall" though this is not straight. This whole winter it hasn't swelled any pitchers but it recently produced a basal shoot which has put out a pitcher which should soon open. My only guess is that something is wrong with the upper pitchers or perhaps they are just slower? I remember reading that the tendrils needed to wrap around something. Several have but they haven't grown into pitchers either.