There are many species of Schefflera, but Schefflera arboricola is the most common species for bonsai.
The three most common varieties are:
Schefflera arboricola Dwarf Schefflera
Schefflera arboricola ‘Luseane’
Schefflera arboricola ‘Moosetracks’
PRUNING... The Schefflera can take severe root and branch pruning. Cut a little above the node to allow for die back. Allow that area of die back to harden thoroughly, then snap off with fingers. Completely defoliate the first couple of years after styling to reduce leaf size, then keep growth tips pinched and older/larger leaves pruned off.
TRAINING... Wiring is sometimes necessary, but use caution, branches are delicate and fast growing. Generally styled in the banyan style. To encourage more aerial roots, place tree in bright light with very high humidity, keep soil a little on the dry side. Paper straws can be used to lengthen aerial roots.
WATERING... Likes water in a well draining soil. I add 10% more organic matter to my soil mix. Be careful not to over water after defoliating.
LIGHT... Full sun for smallest leaves, is one species that does well in lower light such as on a porch or lanai.
INSECTS... As with most fast growing species, Aphids can be a problem. Their leaves are somewhat tender to some insecticides so use caution. Soapy water is best.
FERTILIZE... Any balanced fertilizer will work, only be careful not to use too much for it will increase leaf size. If leaves turn a little yellow, apply some Ironite.
REPOT... From spring all through summer. I try to stretch repotting out 2-3 years for leaves will increase in size afterwards and you will start the whole cycle of defoliating again.
SEASONAL... Protect below 40 degrees. Will sometimes lose their leaves from getting too cold, will not harm them though.