Easy Early Underground Farm

How to farm underground early and without danger.
Inspired by dwarven farming methods.

Dig & Clean

Mine out the area as shown in the image. Be careful not to breach the pool wall.
Let the gnomes clean out the dirt. If you have clay floors, replace them with dirt (Terrain>Replace Floor) - shrooms don't like clay.

Designate & Wall Off

Designate the underground farm - it will end up purple since the floor is not muddy yet. Build the two red marked walls. The empty space between pool and farm is our water reservoir.

Filling the Reservoir

Terrain>Dig>Hole the outer wall (red marking). This can be tricky to correctly designate. As a result, water will fill our reservoir.

Flood the Farm

When the reservoir is full, fill the hole again (Terrain>Fill hole, red marking) and replace the floor above it if you want (Build>Terrain>Floor). Now dig out the inner wall (green marking) and let the water flood the farm. It can be hard to designate the correct square, but you can rebuild (or, if OCD, savescum) if all else fails.
Wait for the water to flood the complete farm.

Finishing Touches

Open the wall to the farm again, build dirt walls to replace the water reservoir and start planting.
In this example you can see my farm was not completely flooded, but with digging and wall building you can fix any farm.
If you have excess water, open the tunnel and let it run out, then replace the floor with dirt to remove the "muddy" property if you want.

Now to wait to actually get mushroom seeds from those greedy merchants...

[base chilena]

how do i get mushroom seeds

[Maxim | MaxFreak]

I have flooded my hole Underground kingdom and all gnomes fell to death on a stair al my 19 gnomes on 1 stair, good that the was a save before I let my farm looded :D cheaty but pfffft

[Nukealope]

Thanks. My Gnomish engineering department sucks at this kind of stuff.

[Azzpissa]

I had no idea how to even start an underground farm, thanks a lot!

[LeoTehJester]

Good Guide, I do it very slightly differently, but this is a great guide for those who don't know how.

[nArrAtor]

Well, I would like to store the water by rain drops in 1X1 and link them after the storage is up to 20%.
Then I put on the floor, wait one day or two...
Got an underground farm on ground...

[Hydro-phobic Water]

And If You Don't Have ANY water On Your Map?

[The Gaming Archaeologist]

my god! SO FUCKING SIMPLE! AMAZING! I've been worrying for ages how to get this working. I must do this immediatly! Thank you so much!

[Erkel Wolf]

great job
its easier to do your way than the way i was doing it :P

[Kedger The Badger]

Actualy this is bit complex, you can just dig a area then let some water in it and keep it there. Thats bit better, cause you can expand the farm anytime you like.