I have got good results with the three clones of var. atropurpurea that I grow by trying to minimise as much disturbance to the plant as possible. I repot well before the plants break dormancy and start growing - dormant plants seem to be more tolerant of disturbance than ones that are growing. When repotting, I also use a gentle rose of water to wash soil from the roots, rather than remove this by hand. I also leave the plants be for the entire season once they start growing -so no moving the pots. A large pot will also allow these plants to grow undisturbed for as long as possible. I am thinking of using pine needles to keep the peat acid and make it last longer and increase the time between repottings.
As for the clones I grow, two have been up for a month now, while the other one is only opening its pitchers today. The best plant I have is one from Fly Free Zone in Queensland called "FRT 1-1". It is more vigorous than the other clones I have and makes very ornate, intensely red pitchers with a big mouth. The photo below is of the first pitcher of the season, which has not completely coloured up. The second pitcher of the season is already becoming darker in the pitcher tube, so it should be magnificent. This plant is also interesting in that its flower has a slight tinge of pink to it - this, and the concentrations of red pigment in the lid, suggest one of its ancestors was a S. leucophylla. I class it as a flava because of the flower and pitcher morphology - the issue with interfertile plants is often where to draw the line of defining a species.
Sarracenia flava var. atropurpurea "FRT 1-1" - pitcher and flower
One of its siblings, "FRT 1-5", starts life as a flava var. cuprea lookalike, but soon becomes solidly red. Interestingly, this clone gets the cut throat of flava var. rugellii, something I have not seen in other plants. It has yellow flowers typical of S. flava. Both it and FRT 1-1 came from a batch of Sarracenia flava seed of unknown provinance sold by the late Fred Howell.
Sarracenia flava var. atropurpurea "FRT 1-5"
The third clone I grow came from Phil Reytter at Lithgow. It gets solid maroon pitchers, but is a much more slender plant that is also slow to grow. Others have has issues with this clone keeping its colour, but stabilising it over a couple of seasons will help. Despite repotting, my plant has come up with the best pitchers yet - I'll post photos once the pitchers open and reach their potential.