Propagation can be carried out in two ways: by vegetative offsets and by seeds.
Pups should be removed when they are one third to one half the size of the parent plant (taking into consideration the width & height). This will allow the mother to produce more pups. The pup should have a firm, brown base & ‘good form’ before being removed. If it feels ‘soft’, leave it for a bit longer. The first pups produced are always the strongest.
Stoloniferous pups (growing on stems) can be removed with secateurs. For pups closely attached to the mother, use a clean saw edged knife, cutting as close as possible to the mother without damaging her soft tissue. Damage to the trunk of the parent invites bacterial or fungal attack, the same applying to the pup if cut too short. It takes months for a pup to recover from too short a cut or being removed when too little. Some dust the mother & pups with fungicide (no copper). Pups growing from the centre of the mother are more difficult to remove & take practice.
Leave the pups for 24 hours before planting. Many use peat or sand or vermiculite/perlite initially till the offset produces roots before potting on into the usual potting medium. Others plant straight into the normal potting mix & make sure the pup is not too deeply planted yet is stable.
Sometimes it’s necessary to tip the plant out of the pot so you can see what you are doing. Also carefully remove any leaves obstructing the view of the base of the pup.
Give the mother a small amount of controlled release fertiliser & she will probably produce one or two more batches of pups.
The best time to remove pups is in the warmer months – mid October through to March, though some avoid the hottest part of this period. Pups removed in the cooler months will not grow & may rot.
Some bromeliads produce small grass like pups called adventitious pups eg Alcantareas. Remove them when they are 10-15 cm tall.
Vegetative propagation does not apply to all bromeliads eg some species of Tillandsia do not pup at all, but produce lots of seeds to carry on the species.
This is a broad topic beyond the scope of this overview. Local bromeliad societies & experienced growers are a great source of information here & I hope to include it as a Newsletter topic in the future.