I get what Nepenthes ak is asking.
Its hard to get plants into the gravel so close without them coming out. Usually just after you plant them they might look a bit sparse but they soon grow and fill in the gaps. People say not to stick bunch plant stems next to each other but when I kept Elodea I did that all the time and nothing bad happened except the Elodea was a pain to keep trimmed.
I myself use sand in my planted tanks but am not expert really. My tanks tend to turn into a bunch of random plants most of them being smothered by java moss(its funny as if you have java moss above where a val runner takes root that val will have some pretty funky leaves).
Java moss is a great plant if you do not mind it being a bit messy at times...I keep it in all my tanks and small containers.
Here's one tank
Here's an old picture of my 46 gallon bowfront(mean't to be display tank, now a hodgepodge of plants).
Looks kind of bland...
Oh dear...I actually liked this layout and the water lettuce but decided to see if I could make it neater. Actually would love to try this again.
Finally this was the tank looking its traditional planted tank best. I eventually decided it was too much work just for looks...the fish don't seem to care too much!
Growing in a tank does not take long as you can see...the first several photos were taken within a few months of the tanks decision to become planted.