how do you keep your plants looking so nice

I'm not sure, although I think some ferts are needed. I don't do anything apart from feed the fish and turn on the lights and that's been enough for the plants. But now I've started seeing a bit of die off. The grass is spreading, but the older growth needs cutting back, and a few plants need replacing as I'm not generally happy with scape.
If anyone has any suggestions on which ferts to use I'm all ears. No CO2 though... tis too much hassle for a simple tank lol.
Also if anyone can identify the swordy looking plants, I'd be grateful. As these start deteriorating as soon as they went into the tank as I couldn't identify them and the identification from the fish store was incorrect (not my usual LFS).
My plans are (see first pic for reference):
Right hand side = thick plantation of hornwort.
Left hand side = thick grass
Middle = I would like some fern/sword looking type plant (any suggestions would be good).
The PH is a stable 7. Hardness .. well I don't have a kit to test that, but our water filters through chalk hills, soo I'm guessing pretty damn hard. (tap water being a ph of 7.5)
Lighting = 2x 36W Aquaglo for 12 hrs a day
If anyone has any suggestions, I'm all ears
