I have had minimal experience at grafting Nepenthes, or any plant for that
matter, but I did have one success several years ago grafting N. rafflesiana
onto N. x mixta rootstock. (See CPN article). This was to see if it could be
done for the purpose of eventually grafting a difficult to grow species (i.e.
macro-vulgaris, northiana) onto an easy hybrid. I believe that grafting to
have two sexes on one plant does not account for the typical growth pattern
of many of the species, that is, a rosette elongates into a climbing stem at
which time basal rosettes and flowers tend to occur (given sufficient
environmental conditions, primarily light). If basals form before flowering
occurs the plant may abort the climbing stem and put the energy into the new
basal shoots. It is somewhat unusual under cultivation to have more than one
shoot per plant in flower, except in large multi-headed species like alata or
mirabilis. Also grafting in Nepenthes has proven difficult in my experience,
(3 out of 4 attempts of various species combinations failed) however, I am no
expert in grafting by any means. The good news is that after 10 (?) years the
grafted plant is still alive and producing upper rafflesiana pitchers.
I believe the best way to produce seed is to obtain several plants of the
same species from the same area or habitat. The plants should be all be given
the proper micro-climate in a greenhouse that suits the species and they
should all be placed next to one another. I used to scatter plants all over
the greenhouse (any still do to some extent) but found that one sex of say N.
veitchii would be flowering in a sunny area and the other sex on the shaded
side of the house would never flower. If seed production is your goal, a
little togetherness makes breeding easier (NO comments PLEASE!).
Cliff