I have done a few like this... Do the whole thing Krylon tan first (you may want to prime, then tan, but thats your call). Then hold the vegetation and spray the green. Just do a small section at a time. The Krylon will wear easily with use, so use the Krylon matte finish over top, with 0000 steel wool between coats. I do 3 coats and it holds up well. Do that, and you will have the picture
Whatever you want to stand out, such as the palm leaves in the other pic, or whatever you choose, do that color as your base. When you spray the vegetation, start about 6-8 inches away. You dont want to put on too much too fast before you get a feel for it. If it doesnt cover well enough, you can move closer, but remember to keep the can moving any time you are spraying, as you do not want it to get too much in one area... Its a fade, not a perfect edged pattern. My duck gun was my most recent, but I decided to duracoat it with the same method instead of krylon, so it is currently being stripped or i would post a pic