Warsenal makes two packs of planters that are really useful for breaking up fire lanes and providing cover. They have Angled Planters and Square Planters.
They don't come with any vegetation, and indeed look alright without adding anything to them, but after painting I added to them a bunch of aquarium plants and other indoor decorative fake vegetation (from Ikea) to fill them out.
I also like what Warsenal did with their "studio" versions, using flock, clump foliage or "coarse turf" from Woodland Scenics to fill them up nice and low.
Using a Hot Glue Gun is the best way to affix these rubbery, plastic aquarium plants to the MDF terrain.
The planters are a mix of MDF for their core and acrylic overlays with all the detail on them. I like the way the Warsenal terrain products use varying thicknesses of materials to add layers of detail.
These were very simply airbrushed using the same colors I used on an MAS District 5 Apartment and all my Underground Lasers pieces: Base coat with VMC Pale Blue Grey. Shade that with VMC Blue Green and VMC Turquoise. Final shading is done with P3 Coal Black, and final highlights are white. Edge highlights are brush-painted pure white.