I've been creating forest walls around my base to limit the spread of pollution, and in some places I need to fill in lakes with landfill so that I can plant saplings there. Of course I discovered that without fertilizing, the saplings never grow (or take forever, I haven't seen them grow yet).
So of course adding fertilizer fixes that issue, but I can only add fertilizer 4 squares at a time, and using the shift key doesn't allow me to place ghost fertilizer so that the bots can set it.

I'd like to be able to create fertilizer blueprints/ghosts so that I can simply label a rectangle for fertilization and the bots just spread it for me (similar to how it's possible to do with landfill).

Interesting idea! The major update is still in the making (I've got no news from our graphics artist in a while, so it may still take some time), and I'll try to add it there.

The issue of trees not growing on landfill should have been fixed since version 1.1.0. However, landfill has a very low fertility, so it is quite possible that most saplings will die. Would you mind testing whether trees really can grow on landfill? I'd suggest to landfill a complete chunk and planting saplings everywhere. That should make for a good chance that at least some saplings grow to trees, if this really works at all. (If manually planting that many saplings seems too much work, you could place a terraformer at the center of this chunk, use the basic planting recipe and let it work for some hours.)

For your real game, there are other means for fertilizing you could use: I've already mentioned the terraformer (use the recipes that just fertilize the ground if you want to have control over where exactly saplings are planted), but there also are seedbombs (rocket launcher ammo) that contain fertilizer.

I've used the map editor to create a large area of landfill and have placed a huge block of saplings on it. I'll leave it running in the background for a few hours and see what happens. I guess it just seemed that the saplings were taking forever to do anything relative to fertilized landfill (trees within a minute) on my real game.

In order to have a control, I wanted to place fertilizer using the map editor, but I couldn't find the entity. Is it possible the fertilizer is not "fully enabled" somehow? I can place saplings and other Bio-Industries stuff, but the fertilizer and super fertilizer icons don't show up...

Thanks for the tips with the seedbombs, I think I might do that. I'm hesitant to use the terraformer as I don't want to string up electricity everywhere. That's what I liked about bots with landfill/saplings, I can just designated a blueprint of landfill, let them complete that, then designate a blueprint with saplings and wait for them to distribute it all.

EDIT: I just discovered the fertilizer tooltip can be adjusted in size! This serves my needs well enough, but it would still be interesting to be able to use fertilizer (and the super fertilizer) in blueprints so that the bots can drop it automatically.

Also, saplings placed directly on landfill just sit there forever (they don't disappear), but I noticed that a seedbomb without fertilizer on landfill eventually results in the saplings disappearing.

I've used the map editor to create a large area of landfill and have placed a huge block of saplings on it. I'll leave it running in the background for a few hours and see what happens. I guess it just seemed that the saplings were taking forever to do anything relative to fertilized landfill (trees within a minute) on my real game.

Thanks!

In order to have a control, I wanted to place fertilizer using the map editor, but I couldn't find the entity. Is it possible the fertilizer is not "fully enabled" somehow? I can place saplings and other Bio-Industries stuff, but the fertilizer and super fertilizer icons don't show up...

Oh, right, that could be a bigger problem than expected! Contrary to saplings, fertilizers have no definitions for entities (which can be placed and mined in the world), but just the items (which can be placed in inventories, used in recipes, dropped on the ground, or picked up). Fertilizing the ground is entirely done by script:

Terraformers choose a random tile in their range, seedbombs use the tiles in a certain radius around the point of impact. If the tile is in the list of tiles with fertility (water tiles or the outer-space tiles from "Space Exploration" are not in there), and if it has a lower fertility value than what the fertilizer provides, the tile will be replaced with "grass-3" (85% fertility) for common and "grass-1" (100% fertility) for advanced fertilizer (the tile names are prefixed with "vegetation-green-" if Alien Biomes is active). When saplings are planted, we compare a random value with the tile's fertility. If this value is greater than the fertility value, the sapling won't grow. Now, landfill is in the list, but it has just a 1% fertility, so most of the time you'll be out of luck. Common fertilizer makes for a fertility of 85%, so the saplings will grow most of the time; and advanced fertilizer provides 100% fertility, so they will always grow.

I guess we need a ghost-entity for fertilizer (a real entity wouldn't be needed because we'd just replace the tile when the item is used). Perhaps we could just use the item's icon for the ghost? Or would it even be possible to create tile ghosts? Not sure, I'll have to think about it. :-)

Thanks for the tips with the seedbombs, I think I might do that. I'm hesitant to use the terraformer as I don't want to string up electricity everywhere. That's what I liked about bots with landfill/saplings, I can just designated a blueprint of landfill, let them complete that, then designate a blueprint with saplings and wait for them to distribute it all.

The gardens are another option (there will be bigger versions in the next release), but of course, they also need electricity …

I'd like to be able to create fertilizer blueprints/ghosts so that I can simply label a rectangle for fertilization and the bots just spread it for me (similar to how it's possible to do with landfill).

I've figured it out! We're removing certain tiles from blueprints, which also prevents the blueprinting of fertilizer. The reason is that both common and advanced fertilizer place different tiles when Alien Biomes is active. So if you'd create a blueprint, then add or remove "Alien Biomes", and then try to build the blueprint, the game would probably crash because the blueprinted tile isn't available. We'd have to go over all blueprints and update the tiles there. That may or may not be possible (haven't checked yet), but that could involve the risk to ruin your blueprint library. As I've never dealt with modifying blueprints per script, that's something I don't want to do yet.