Box art - Resident Evil 2 Remake

Resident Evil 2 remake Herbicide Puzzle | How to kill Plant 43

The Resident Evil 2 remake is filled with terrifying action and clever puzzles, but it can be difficult to solve those brain-teasers when a zombie’s chewing on yours. You may have thought the Clock Tower puzzle was annoying, but probably the toughest and most infuriating conundrum in the game is the Plant 43 puzzle in which you have to mix the Herbicide.

You’ll find this particular puzzle later in the game, where you’re tasking with eliminating a giant carnivorous plant, and you’ll need to solve the puzzle to get the herbicide needed to destroy Plant 43. We’ll go through all the stages you need to do to craft the herbicide, including how to solve the mixing puzzle. Let’s do to that plant what we did to the ones on our windowsill.

Where is the Herbicide in Resident Evil 2 remake?

Plant 43 is located in the Greenhouse, which takes up most of the East Area of the NEST Laboratory, where the final chapter of Resident Evil 2 takes place. While you’ll have to explore most of the East Area in order to solve it, the herbicide mixing puzzle specifically is located in the Drug Testing Lab. You’ll have just encountered the plant zombies, called Ivies, for the first time, and a few of them will be wandering the Greenhouse area. It’s otherwise safe to enter from the Greenhouse Control Room, and you’ll be able to easily avoid the Ivies and head left into the Drug Testing Lab. There’s an apparatus you can examine, but it looks locked up, with a shutter across. This is the mixing puzzle, so let’s get that shutter open.

How to access the Plant 43 herbicide mixing puzzle

If you look at the mixing puzzle, on top of the cage you’ll see two symbols, which seem ripped on the side. You may have noticed a control console in the Greenhouse Control Room which seems to accept these exact symbols. Unfortunately, as the code is incomplete, you’ll need to find the full code somewhere else (it would take far too long to guess). We’ve got a full guide on how to find these Laboratory codes right here, for both a first and second story run through the Resident Evil 2 remake as the codes change between campaigns. Here’s the short version.

One thing that doesn’t have an incomplete code is the hatch just south of the Drug Testing Lab. Avoid the plant creatures, grab the code off the hatch, then head back to the console and put it in. The hatch will open, allowing you to continue to the lower floor. Explore the area, being mindful of zombies, Lickers, and Ivies, since you’ll encounter them all. On a table in the open Lounge area you’ll find a trophy. Pick it up, and examine the underside of the trophy for the code to the Drug Testing Lab mixing puzzle code.

Note the nearby junction box by the vending machines, since you’ll be needing to come back here soon and do something with it. Head upstairs, and if you’re playing the initial campaign grab the electronic Signal Modulator from a similar junction box on the left. If you’re playing Story B, you’ll have picked it up from a dead soldier near the central Laboratory lift area. Head back to the Greenhouse Control Room console, punch in the code you found on the trophy, and the mixing machine shutter will open.

Where to get the Dispersal Cartridge

Before you leave the Greenhouse Control Room, there’s something else in here that you’ll need before you attempt the mixing puzzle: a Dispersal Cartridge. Just to the left of the console, and in front of the window facing the greenhouse, is a Solution Dispenser. Use it, and it’ll spray something over Plant 43, but doesn’t seem to do anything. It will, however, eject the Dispersal Cartridge you need in order to mix the herbicide. Take it, and head to the Drug Testing Lab for the next stage, so it’s finally time to solve the actual puzzle part of this adventure and get the herbicide, “UMB No.21.”

How to solve the Resident Evil 2 remake Plant 43 Puzzle

Use the Dispersal Cartridge on the mixing machine, and you’ll be presented with the Greenhouse chemical puzzle at last, which you can see above. The objective is to get a certain amount of the green chemical in the left tube, with the objective highlighted in a ring around that tube. Pressing the red button will switch the left and middle tubes around, and pressing the blue button will switch the middle and right tubes around. The green button will empty the contents of the middle tube into the left tube, at least until it hits the stopper.

It’s a variant on a classic liquid-switching puzzle, where you have to empty a liquid between different size containers in order to get a certain amount. You have to switch the tubes around, leave some liquids in one, switch again, until you get the exact amount. It’s pretty straightforward, but the presentation makes it a little tricky. Notably though, there’s an achievement for solving this puzzle in eight turns. If you want that achievement, or you’re just getting frustrated, here’s the correct order to press the buttons:

Red, Green, Blue, Red, Green, Blue, Red, Green

However, if you’re playing through the second story campaign, you’ll probably have noticed that the solution has changed, and that combination doesn’t work. Here’s an easy combination for the story B mixing puzzle:

Blue, Red, Green, Red, Blue, Red, Blue, Green, Blue, Red, Green

If done correctly, the green chemical will drain out and the Dispersal Cartridge will pop up, filled with green liquid. Now the hard part’s out of the way, it’s on to the next stage, which fortunately doesn’t involve any puzzles. Well, maybe a small one…

How to create Herbicide and kill Plant 43

If you go back to the Greenhouse Control Room and input the cartridge, it’ll eject it with the command that it needs to be cooled first. If you remember the note you picked up with the Dispersal Cartridge, the mixture indeed has to be cooled before it can be used. Head back down the hatch, and make sure you have the Wrist ID Band and Signal Modulator with you, otherwise you’ll need to go and pick then up from wherever you left them.

Remember that junction box next to the vending machines in the Lounge? Head there. It’ll have three letters on it. Examine the Signal Modulator, and change the setting to those three letters. Now it’s time for that other puzzle, we’re afraid. Fortunately it’s quite an easy one: simply tune the two signals at the bottom to match the one at top. Once they’ve matched perfectly, exit out of the Modulator and use it on the junction box. If you’ve done it right, the power should come back on, and you can access the door on the left.

Watch out for zombies, and head through the now-powered door to the Low-Temp Testing Lab (see map above). Put the Dispersal Cartridge in the machine in the center of the room, and after a few seconds it’ll eject it with the final herbicide mixture. Head back to the Greenhouse Control Room (watch out for Ivies, there’ll be more of them now, kill them with fire), and put the now-completed herbicide into the sprinkler system where you got it. It’ll spray the herbicide and kill Plant 43. Head in to get the ID Wristband from the dead scientist, but be aware that the Ivies are only stunned, not dead. Furthermore, killing the plant in Leon’s story A will alert an old friend… be ready to run!