Summoning falling grass in an area

Question

I've recently made some "sculpture" in Minecraft. To make it look more natural, I've decided to cover it with grass. For this I intend to summon falling grass blocks with /summon FallingSand ~ ~ ~ {TileID:2,Time:1}.

The problem is that the /summon command only works at one coordinate; I want to summon these at each block in an area. Is this possible?

Answer 1

The /summon command is only usable on entity, like mobs, FallingSand/FallingGravel, arrows, etc. The biggest problem with that command is that you can only summon one entity at the time. If you want to summon multiple entity without repeating the command for each entity, you should use command block loop.

Anyways, the most simple way to cover your "sculpture" is to use the fill command following those simple step:

1. Cover your "sculpture" with a layer of sand, using that type of command:

   /fill ~ ­~20 ~ ~25 ~20 ­~25 minecraft:sand 
   

2. Replace the sand you just place with grass, using that type of command:

   /fill ~ ~20 ~ ~25 ~20 ~25 minecraft:sand 0 replace minecraft:grass
   

Be careful if there is sand blocks in you "sculpture", you better use gravel if you don't want them to be replaced.

Answer 2

You could fill an area really high up, and then quickly set all fallingsand to grass

/fill ~ ­~220 ~ ~25 ~220 ­~25 minecraft:sand
/entitydata @e[type=FallingSand] {TileID:2}

This way you have no risk of changing parts of your sculpture if they're made out of sand.