I'm afraid I'm one of those bastard people who never have problems growing live plants in their Aquariums. I have a couple of friends who've never bought plants, as they are amply supplied from my cuttings. Maybe it's the 'farm-boy' background?
When I set up this 250 litre (~70gal?) tank (48x18x18), I did have the plants in mind, probaly more so than the fish. My tap water is Soft, at 7.1 pH. The tank runs at 26-27c, I have 1cm red clay/soil under 6-7cm of gravel. I use liquid and tablet fertiliser at totally random intervals (occasionally I may test for Iron (Fe)). I have three 36watt Quad Phospher 5000k tubes. I use Bakers Yeast to generate CO2, applied via a Bubble Maze. I recharge this once a month, if I remember.
Now, this Post was prompted by a comment from Mizpriz after she checked out my web page. I took these pictures to demonstrate what happens when you spend all your time on Fish Forums, and not looking after your tank. The plants get so thick, there's hardly any room for the fish. Even the poor Cory's have trouble getting to and from the surface!
This represents about 3 weeks of neglect. I usually do a bit of a trim every fortnight, and it's been about five weeks now. In this second pic, you can make out the black fuzzy stuff growing all over the front glass - Red Algae. Obviously a water change and top-up is also due. And I've no doubt, there's a swarm of Guppy Fry in there!
I once identified up to five types of Algae simultaneously in the tank (I've never been much of an Algae worrier). But as I'm about to introduce my 30 juvenile Bristlenose, and a dozen Otocinclus, that should make things tough on it in any case!