I have no idea if you need root tabs or not. What are you feeding? What kind of substrate do you use? If it is soil-based or something like Aqua Soil, how long has it been in the tank?
If you are feeding a tank of things like Java fern and anubias, there is no point of using root tabs. They are perfectly happy being fed from the water column. On the other hand, if you have heavy root feeders, they would be happy to get some food if they are not being fed via your substrate already.
Details would be helpful here, just sayin'.
Since this is not a dedicated plant tank, I have just regular gravel. I do have a few anubias plants. some are clinging to the gravel (rhizome above gravel) and others are on driftwood.
Here are some other plants I have:
Helanthium bolivianum angustifolia
Hygrophila corymbosa 'Compact'