5g?

A 5g tank isn't very tall, I'd stay away from stem plants. Cabomba, anacharis, and hornwort all grow very fast and you'll be trimming frequently.

I use narrow leaf java fern as a background plant in my 12g tank, it grows tall enough and rarely need trimming. Other plants you can use to fill in the tank are anubias nana for the foreground, marimo balls for something different, and marsilea clover for the foreground.
 
I've got a 5.5g planted and have grown lots of plants in there. Most I've moved out once they were too big.

Right now I've got anacharis, Hygrophila Difformis, Java fern, Java moss, and a mondo grass thingy. The anacharis and Hygrophila need trimmed often, so you may not want that. The Java fern is fine, Java moss is a little unruly, and the mondo grass is just the right size, might be a good option for your number 5 plant if you don't mind that it is pretty much a rosette.

You could consider Pennywort for your number 4 plant, but again, you would likely have to trim it often. I'm partial to spiral Vals where you have your Number 1 plant, but they would be bent over at the surface and would likely go diagonal at some point.

My favorite plant that I had in my 5.5 and would highly suggest was an E. Parviflorus. It looked great in there and was a perfect as a focal point. For some reason that currently escapes me, I decided to move it to another tank where it now lives and is thriving.

Good luck!
 
Just note that mondo grass isn't an aquatic plant and will die over time in your tank. They are a bog plant and will grow in a terrarium, but will not survive completely submerged.

I would recommend rotala rotundifolia. It grows very well in my 5 hex with 10 watts of light, but it doesn't grow too fast. Under this lower lighting it stays a green color. If put under higher light the tips will get a nice pink shade.

I would stay away from vallisneria, since it usually likes higher light and root fertilization to do well.
 
I've got Caridinal Flower (lobelia cardinalis) and Pygmy Chain Sword growing like MAD in the 5g in my sig, and yet my Anubias Nana and Java Fern are dying off... I find that it seems to be that the plants will really only grow directly under the light source, and I also have Hagen CO2 and I dose Flourish Trace 2/wk and Plant-Gro NPK weekly so I'm sure that helps.

I'll try and get a new picture up in the next day or so and you can see it. I have to trim the lobelia weekly, so it can be done.
 
well some plants are in! So far i have one anubis nana(attached to driftwood) one java fern (in the back) and some java moss.
 
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