WHAT glue secures ground cover to 2 inch thick blue styrafoam?

Personally John, I would paint the foam first, with an earth color. The paint could secure ground cover all by itself. White glue works well. For larger clump foliage, hot glue can work, but be careful, because it can melt the foam.

I agree with Elliot.  Buy the cheapest latex paint -  tan, brown, green, black, etc.  Apply with a brush in a manageable area. While the paint is tacky, apply the ground cover.  If more ground cover is needed, white glue (straight from the bottle or diluted, your choice) will work fine.  If chunks are going to be applied in places or on a vertical surface, put the white glue in a small pan/dish, dip the chunk(s) and place on your layout.  Respectfully, John in Lansing, ILL

or use lightweight drywall compound over the Styrofoam, shape it, color it first or use spray paint after it dries. 

So far I have already painted. I have never used this blue phone before. I think I may give white glue a shot. I have built a relatively small modular layout. So this one is going to move. Hoping to find some clever way to keep the ground cover in place. There isn't that much of it. I am concerned about melting phone because of all the horror stories I've heard. It looks decent enough painted but I would really like to have ground cover.

Actually, a little "melting" can be a good thing in this situation. I often deliberately use a dusting of solvent-based spray paint to soften the shapes of blue foam. If not overdone, it gives a nice, weathered, eroded look to shapes that would otherwise look artificial.

Spray photo-mount adhesive can be handy sometimes. That said, I usually use white glue.

I have used paint and 50-50 white glue and water with some drops of 90% alcohol.

Dave

As DAVID stated above, 50/50 white glue and either a few drops of alcohol or a few drops of dish detergent.

First, I put a very heavy coat of dark brown latex paint down. Then while it is still wet, I allpy the ground foam to my liking. Then I come by with a spray bottle of diluted elmers glue with some dish soap added. Everybody says a 50/50 mix but I alwasy find that its too thick to spray and jsut ruins the sprayer so I wind up with more like a 25% mix of white glue and warm water. The warm water help to soften the glue wo it will dilute. Then I add a generous shot of Dawn dish soap to break the surface tension. Some say a few drops but thats never been enough to get the proper results I was looking for so  added a tablespoon or so to get it right. Then I applyit until it saturates all the way through the landscape material

Im just discovered SOBO glue (at Hobby Lobby) and it is the best "white' glue I've ever used.  Six bucks for eight ounces. 

Fusion Fiber works well for me. A thin layer gives texture and no glue needed. Just sprinkle the cover and use wet water to bond to the fiber.

1) I think the "few drops" of detergent recipe applies to the case in which you are adding it to plain water intended to spray onto a surface. For that purpose, a few drops is adequate. If you are adding it to the adhesive, you need more.

2) If you are buying white glue, consider getting a gallon jug from Home Depot. Vastly cheaper per unit, and will last a lifetime.

All blue board glued together.  95% carving , painting and light texture done in garage.

I give everything a coat of latex paint and still wet sprinkle on the light texture then spray matt medium on, then more texture. On flat surface I like fusion fiber, that stuff is great ! and you can reuse it, or change it. When everything is the way I want it I spray on more matt medium mixture. Somewhere I posted a whole series of photos on this project from start to finish.

#1......the flat surfaces will receive fusion fiber, so far no glue just paint and light texture.

#2......some trees in, I redid them and planted a whole bunch more 

#3....pretty much all texture in now,   In order.....wet fusion fiber in places..... paint.... texture.....matt medium mixture overcoat. The power plant is on opposite side of this mountain. 

#4.....More trees and all texture improved 

More trees have been planted after this photo was taken, I plant more trees after every York meet. I'm always looking for better glue

  I'd check with the mfg. on even laytex paints for compatability. Color means little and there have been a few other surprises posted on the forum concerning what else sat on foam/paint combos (vehicle tires, structure bases, etc.)

Primers tend to be more stable on soft substrate, provide a barrier layer, and allow best adhesion.  It's what they are meant for really. (Some glosses provide an excellent barrier as well, but smoothness is an adhesion issue.)

White glue & water & alcohol.   I just don't trust that detergent soap would'nt cause a long term weakness in the glue as it doesn't evaporate the chemicals used to break up molocule bonds.  I know a great BASF chemist, but never remember to ask his opinion  .

(Too busy feeding off each other's sillyness )

All done with Fusion Fiber, even the ballast.

You can also try good old fashioned hairspray, too, if it's lightweight ground cover (turf and small clumps) - pretty cheap brands at Walmart that hold well.

Try it in a small area first to see if it does what you want.