Propagation By Basal Stem Separation
Propagating Nepenthes by basal stem separation is very strait forward. A basal stem is a new plant which is created off of the mother vine from beneath the soil. A nice feature of basal stem separated plants is that the separated plant will produce lower pitchers, whereas the mother plant is likely producing uppers on the main vine. A Nepenthes vine will stop producing lower pitchers, and begin producing uppers at some point. But the mother plant can produce new lower pitchers off of the new basal shoots that it develops.
In the above diagram, (very rudimentary, I'll create a better one when I get time), the main mother plant has created a basal rosette (7). This plant is attached top the mother plant via a basal stem connection/ Over time, the basal rosette will form its own root system off of the basal stem. When this occurs, you can simply separate this basal plant from the mother plant and pot it up like a regular plant.
Basal stem propagation rarely fails if there is no root system on the new plant. The basal connecting stem acts somewhat like a root until the new roots develops. The strike rate for basal rosettes that were separated without a root system has been about 90% for me. The strike rate for a basal stem propagated plant with developed roots is 100%.
Basal stem propagation is probably the fastest method of propagating a new plant. A large motherplant can produce many new basal plants at the same time. You can allow these to grow until they develop their own root system, and remove them all at the same time. Once they are removed and potted, they are basically growing on their own. Removing these plants rarely shocks the new plants or the motherplant. So all plants involved continue to grow without shock being induced.
Basal stem propagation works well, even in species in which cuttings are very difficult.
Basal stems are encouraged to grow when the growing tip of the main vine grows some distance from the main plant. The growing tip of the vine contains a harmone which suppresses dormant nodes along the vine length from developing. There are a couple of species in which the main vine will divide further up the stem, but in most the harmone in the growing tip keeps this from happening, and a new vine will only develop frmo the base after the growing tip has grown some distance away from the base of the plant. This harmone likely keeps basal rosettes from developing until the vine growing tip is some distance from the basal area of the main plant.
One trick to force a vine to create basal shoots is to train the tip of the vine below the root system level. You can tip the pot over on its side in order to make this easier, although longer vines easily flop over and can be dropped below the soil level. The growing tip being below the soil level causes basals in most species to immediate shoot.