I am in the camp that thinks the spectrum of the light is not crucial to growing plants, at least not the different spectra between fluorescent tubes. Some people have the opinion that it makes a bigger difference.

One thing that may be important to you is how the plants appear under the lights. The special plant lights are a funny pinky/purpley colour and they can make plants look funny. A standard cool white tube that would probably be fine for growing will make the plant colours look a little flat. If you want the plants and flowers to look good then you should hunt down a tube with a CRI number above 90. They are more expensive but they look better. They may be labelled as full spectrum or daylight, but don't rely on the words, check that CRI number. You can get CRI 96 tubes fairly easily that are almost indistinguishable from natural light. The high CRI probably won't make much difference to the plants, but again some people say they work better.

The other thing to make sure is that you have enough light to keep the plants healthy. With only one tube, you are probably going to be a little short on light. Its hard to give more specific advice without knowing the terrarium size and the fitting details.

P.S. Good choice with the Saxifrage there :)

Thanks for your input. This will help. The terrarium is just a standard 10 gallon. I realized after I started that this isn't sufficiently large enough for much so later on I'll probably upsize. I'm not sure what is meant by 'the fitting details'.....?
Also, any idea what's wrong with my nerve plant? It's got little holes in the leaves. Not all the leaves, it's sporadic.

Here is a link that might be useful: Nerve Plant