This guide provides a complete, step-by-step solution for the Greenhouse Lab and Herbicide puzzle in Resident Evil 2 Remake. Whether you’re playing the A-Scenario or the B-Scenario, this will walk you through every step to get past this challenging section without any wasted time.
This puzzle has three main parts:
- Entering the correct codes in the Greenhouse Control Room.
- Mixing the Herbicide in the Drug Testing Lab.
- Cooling the Herbicide and using it to clear the path.
Part 1: The Greenhouse Control Room Codes
The first step is to enter two separate codes on the control panel in the Greenhouse. One code lowers the ladder, and the other unlocks the herbicide synthesizer in the Drug Testing Lab. The codes are different depending on whether you’re on a 1st Run (A-Scenario) or a 2nd Run (B-Scenario).
The keypad has symbols instead of numbers, but you can think of them like a standard phone keypad:
- Top-left is 1, top-middle is 2, top-right is 3.
- Middle-left is 4, middle-middle is 5, middle-right is 6.
- Bottom-left is 7, bottom-middle is 8, bottom-right is 9.
- Bottom-center is 0.
A-Scenario (1st Run) Codes:
- First Code:
3123 - Second Code:
2067
B-Scenario (2nd Run) Codes:
- First Code:
2048 - Second Code:
5831
Quick Tip: You don’t need to find the codes in-game. You can simply input the correct numbers for your playthrough and the doors will unlock, saving you a trip to find the DNA Trophy and the lab notes.
Part 2: The Herbicide Synthesis Puzzle
Once the Drug Testing Lab is unlocked, take the Dispersal Cartridge from the Control Room and place it into the synthesis machine. The goal is to fill the large cartridge on the left up to the red line. You will need to move fluids between the three smaller cartridges using the colored buttons below them.
The button sequence is different for each scenario. Follow the exact order below without making a mistake.
A-Scenario (1st Run) Solution
Press the buttons in this specific sequence: Red → Green → Blue → Red → Green → Blue → Red → Green
B-Scenario (2nd Run) Solution
Press the buttons in this specific sequence: Blue → Red → Green → Red → Blue → Red → Blue → Green → Blue → Red → Green
After you complete the sequence, the machine will mix the Herbicide and the cartridge will be filled.
Part 3: Cooling the Herbicide and Dispersal
The last step is to cool the newly synthesized Herbicide.
1. Go to the Basement: Take the ladder you unlocked in the Greenhouse and go down to the basement area.
2. Find the Signal Modulator: The Signal Modulator is found on a desk in the Lounge. Pick it up.
3. Power Up the Lab: Take the Signal Modulator to the switchbox located in the Low-Temp Testing Lab.
- Examine the Signal Modulator in your inventory.
- Rotate the dial to align the frequency wave on the screen with the frequency shown on the switchbox. The correct frequency is ‘OSC’.
- Once aligned, use the Signal Modulator on the switchbox to restore power to the lab.
4. Cool the Herbicide: Place the filled Dispersal Cartridge into the cooling unit in the Low-Temp Testing Lab. Wait for it to finish.
5. Disperse the Herbicide: Return to the Greenhouse Control Room and use the cooled, completed Dispersal Cartridge on the final panel. This will disperse the herbicide, clearing the large plants and allowing you to reach the dead scientist and obtain the Senior Staff ID Chip.
This completes the puzzle, and you can now continue through the rest of the lab.