I think there may be a line of sight element as well.

You can see them pop in but are typically already spawned. If you are in an area and kill them off new spawns will tend to be behind things from your line of sight.

So if I want to keep an area clear of random spawns I find it easier with removing the clumps of trees and ground clutter.

I think this may give the impression of grass spawning mobs... I have kept my foliage off for a long time but I don't know if that level of stuff would actually work that way or not.

I've been clearing the brush from around my digs for wood, resin and defense, but I didn't think about it making spawning more difficult. I leave the small brush and large trees, take the stumps, etc. and that creates a park.

But if they can't spawn when you can see them... Blink.

Originally posted by StronkWalrus:

Is it true that grass spawns mobs?
Read about it in a guide and just wondering if it is true or outdated

Spawns have different dynamics on how they spawn.

Obviously spawners like for draugr skels etc that you see visually are known spots that will spawn things.

Activities you do in different biomes spawn/attract mobs to you. Most of the time it is in a radius to you(similar to the event spawner radius).

And then there are the random spawning of biome appropriate mobs as you just move around(again with the radius mentioned), if you're lucky you can actually see them spawn in/render slightly off the ground and land for some.

Other factors:

Nigh time of course causes higher spawn rates.
Rain storms will spawn more necks in meadow biome.

Some subzone areas of biomes will have more propensities to spawn specific creatures(ie necks around water sources in meadows for example)

And there are others.

Also as partly mentioned, killing mobs then leaving render then coming back and cause respawns(sometimes seems on a timer too though). Note too that some areas (like in the meadows) can have a dynamic spawning area where different mobs have a rotation/random rotation of what spawns next in that rendering area.

Mobs spawns everywhere in a 64mx64m square you are in ( depends of biome you are too )
Only stops if you are close to a workbench or some other building