I like scheffleras and grow them in my basement under regular shop lights with T8 cool fluorescent bulbs. They remind me of palm trees on some tropical beach. They are very tough and almost bulletproof.
Growing any plant will be much better and easier if you use a well draining substrate suitable for bonsai. I use turface and bark at about 80/20%. There are other materials and ratios that will work just fine. The only thing about bonsai soil is that it must be watered frequently. Potting soil is no good in our climate.
They don't take a great deal of water in the winter. A good idea is to place a bamboo skewer into the soil. Water when they are dry (this is for winter, they'll take more water during growing season). They grow very slowly in the winter.
I bring mine outside around end of May, pump them up with sun, water and fertilizer and chop the trunks in the first part of July. I prefer not to chop in winter the growth is too slow (but you probably could if the plants were healthy).
I chop mine every summer and they are getting nice, short with thickening trunks. I also read the info on FUKU Bonsai but remember they are in Hawaii and have an ideal growing environment much different than ours. Therefore we have to adjust culture to our conditions.
Inside I give them good air circulation with a fan a couple of hours every day and shower or mist once per month to keep them clean and discourage pests. I feed at 1/4 strength about once every 6 to 8 weeks during winter. Outside, growing season, I give mine morning sun and afternoon shade and fertilize with something like regular miracle grow, at recommended rate, every 2 weeks.
You can buy a big pot of schefflera with decent trunk sizes at Home Depot, Lowes, Walmart or a garden center (just houseplants) for @ $10. Unpot and separate the plants gently and then replant as you like, do this during the growing season. Let them sit for a month and if they look healthy, chop away. If you want them to develop, plant in a larger (not too large) pot and not a small bonsai container and grow lots of foliage to thicken the trunks.
Generally just search the web and read up on all things bonsai. I found a bunch of books at the public library. LOts of videos on youtube. The best thing is to join a club.
Chinese elms grow very well outside in our area.
Best,
Augustine,
Central MD - 7a