I'm sure others have discussed this before. But I wanted to highlight a really simple way of making thick vegetation terrain for your tabletop. I'm going to use these for our current Pirate Borg roleplaying campaign.
The church is from Sarissa Precision and is a 28mm scale Mediterranean Church
Aquarium and table setting plants pulled apart and ready for use
I started with finding a suitable sized base and, using PVA glue, sanded it. Once dry, I undercoated it in a light brown spray.
I then took cheap aquarium plastic plants and plastic table setting plants and pulled them apart. I then hot glued a random assortment of plant types and colours onto the base. Being hot glue, I had to hold each plant in place as I waited for the glue to dry. I also pulled off the strings of dried glue as I went.
I then used PVA glue to add small gravel stones to the base. Once those were dry, I then added some small grass flock around the base to hide some of the more obvious areas of the dried hot glue.
Just added the grass flock to the base of this one
So pretty cheap and pretty versatile. You can make whatever you want from such plants. You could even use the tiny fern like plants, which come from an aquarium plastic plant, to make corral polyps for underwater terrain.
So, there you go. I'm not the first to come up with this idea. But hope this gives you some inspiration for making cheap vegetation for your own tabletop.