How do grass blocks work?

[Tigerlore]

I'm confused.

The wiki only says "Grass will grow on dirt if it is exposed to sunlight or bright light after some time." http://wiki.minetest.net/Dirt_with_Grass And, after hours of trying to get some grass blocks to spread from one island in an ocean to another and seeing absolutely no progress, I believed it didn't spread. Then again, I never saw any grass blocks appear spontaneously either.

I cheated in several stacks of grass blocks, placed them in the world and then later hoed some for a farm. I didn't know the hydration radius and some turned to dirt and then, quickly, to grass blocks.

There is a recipe for grass blocks and I would have made some if I had known they would spread, but the wiki doesn't say that and for some reason I didn't see that in my world until after I cheated in a bunch of them.

Maybe someone who knows how grass blocks work can change the wiki?

[paramat]

The wiki is out of date on this.
dirt_with_grass, dirt_with_dry_grass and dirt_with_snow will spread in bright light, but no longer appear spontaneously on dirt. However you can now create these nodes by placing either 'grass' or 'dry_grass' plants or snow on dirt, they take a while to convert.

[Tigerlore]

Ah, thank you. This will help a lot. Grass blocks are surprisingly important to me in games like this...