Botany Manor

once you find the Oscilette seeds in the boathouse you can begin to grow the Oscilette by doing the following:

1. fill a pot with soil at one of the plant worktables
2. add an Oscilette seed to the pot
3. water the seed (some people say this step is not needed but i found myself doing it out of habit)
4. take the seedling to the boathouse and place it in the designated spot near the phonograph
5. pick up the Meadow’s Bliss tube and place it into the phonograph
6. turn on the phonograph (achievement unlocks when plant is done growing)

To grow the Oscilette, follow these steps:

1. Fill a pot with soil
2. Add an Oscilette seed
3. Water the seed
4. Take the seedling to the boathouse and place it on the tray near the phonograph
5. Place the Meadow’s Bliss record into the phonograph
6. Activate the phonograph

As there is other guides before this please see them first.

Chapter 5
You will find this plant in chapter 5 after entering the boat house.

1.Add soil
2.Add Oscilette seed
3.Add water
4.Take the plant up to the building above and place in it's spot next to the phonograph
5.Add the Meadows Bliss song to the phonograph, it should be the middle one on the left side next to the window with the white label green edges
6.Start the phonograph with the lever and the music will begin and the plant will grow

If you need more help with this you can see my video below:

Chapter 5

To grow Oscilette: Fill the pot with soil, add the seed, and you don't have to water it. Place the pot next to the phonograph in the boathouse. Grab the record that lists 120 BPM on the case and use the phonograph to play it.

Full video walkthrough including all achievements, puzzle solutions, and collectible locations! (Timestamps in YouTube Description)