As Kas sais, they can be a lot of work, I spend about an hour or more each week on my 33g pruning and rearranging. More lately because I was very busy and let CO2 run low so I had a lot of algae to deal with.
On the other hand, my 18g tank is planted with slow growing, shade tolerant plants (anubia, crypts, java) and has only the 15w fluo. light that came with the tank. They plants are healthy and grow very slowly. There's a tiny bit of algae in the tank, but it's mostly inconspicuous and is well within what I can tolerate

. This one just gets a 50% water change every week. The nutrients come almost solely from fish food/wastes. I do dose a little nitrate at water change time, but only because I've noticed that my plants are using up more nitrogen than phosphate, so I dose to prevent a BGA (blue-green algae) outbreak and to keep the plants healthy. I also dose some traces, but on such a low light tank, something as simple and uncomplicated as the stuff available at LFS' would do, I just do seperate dosing because I've already got all the gear for the high growth tank.
To sum up, a planted tank needn't be a lot of work. My low light tank looks great (to my eye), it doesn't photograph well because of the low lighting, so I had to use the flash, which washes out the depth, but hey...