First of all I’m not sure if you’re speaking of painting your environments (plants, trees & bushes) in the traditional way or digital.
I usually do paintings traditionally, and painting plants and trees is one of the most enjoyable parts for me. Mostly painting plants and bushes…..and so on, these are not the main focus of the painting and depending on the light source in your work you can express them in silhouette. There are examples of how people do this all over CA.
Most of the time there is really no reason to paint each individual leaf or blade of grass. Spotlighting a few that are near your main subject may be necessary to convey the reality of the painting or drawing but after the environment moves out and away from the focus it can become blurred and abstract, just something to kill the empty space around the edges and drive the viewers eye back to the main focus of what you want them to see.
Next, a great way for deciding how you are going to approach this is to look at nature itself. That is always inspiring!