Because my time is limited I can usually only focus on one or two of my hobby projects, while the others sit there wasting away.
I am looking for a solution that would allow me to divide my time better. is open sourcing where I take the role of guiding the project realistic, or are there better solutions?
In my case, one project has a reasonably sized community of users going for it but is currently closed source. There have been requests to open source it.
Open-sourcing may indeed be a good idea. If your project is interesting and useful to others, fellow developers may come quicker than you would think. It may also be a great pleasure and motivation for you to see others pick up your work and contribute to it.
On the other hand, if you open-source a project it is not just done by throwing it on Sourceforge. To make the project attractive to fellow developers, it should have:
I did this with two projects of mine. After some months, they were included into major distributions. After another time, I found a french guy writing a whole gui for one of the projects. Several developers were interested in the other, but eventually nobody really sent a patch.
If you just do it half-assed -- throw it on Sourceforge and then upload a new version every second year -- I don't see how it would help. The more you invest in it, the more attractive your projects are to others, the more revenue in developer help you will earn in the long run.
The answer to your case may be to think about which projects are really/most worth these efforts and then continue with them.