"Vermi" usually derives from the latin name for worms, which suggests it might be toxic to worms. Looked up the Aroid site, that's a very nice looking plant. A bit reminiscent of Typhonium (and some other aroids). Where does it originate?
Here's some tips on growing Synandrospadix. I've grown large ones to blooming and seeding, and just recently grew two from seeds to blooming size. They seem to respond well to very moist soil. What I did last year is I put the pot in a saucer that allowed me to keep weak fertilizer water in the saucer at all times. Every 3 or 4 days, I'd dump out the old water, let the pot drain for a few minutes, then water it with fresh Miracle Gro fertilizer solution (1/2 to 1/4 label rate). The corms went from being about an inch in diameter to being 4+ inches in diameter, and one is going to bloom this year.
They won't do too well if allowed to become too dry. The soil mix should be well draining to provide root aeration, but not dry.
A constant feed is preferable to periodic "jolts" of fertilizer. That is why I shared about using a lower concentration of Miracle Gro, but using it constantly (i.e. in the saucer water, and at least once per week applied from the top through the soil ball). This has worked very well for me. It is also the method used by several of the best and most professional aroid growers I know of. There are some other aroids that respond well to this same type of regime, such as Dracontium and Pycnospatha.