Foregrounds can often be a pain in the neck, and are often not considered properly until the rest of the painting has been completed. This is not good practice, of course, as it's by far a lot better to give the foreground some thought before you start painting. Anything but the simplest of landscapes will benefit from one or two studio thumbnail sketches to help you decide on the main features and relationships of the composition.
On a hike recently I wanted to find a spot where the river created a really good lead-in to a mountain, but there was no path. The dense vegetation simply got worse as I battled upstream (without a machete - they don't like you carrying them around these days, and my Swiss Army knife wasn't quite up to the job). If, rather than fight it, you wish to paint such dense vegetation, then the semi-abstract system as in the bottom left of this painting, can be the best option. Enjoy your painting/hacking!