In order to get to gardening, cultivation and harvesting, you’ll first need to unlock the garden at all. There’s two ways to do this, depending on where you are in the game.

In the first half of the game, you’ll need to complete a specific side quest, ‘Shopping List’. This quest is obtained from a woman NPC found in the Marketplace area of your home Village. This unlocks the basic feature of being able to use the garden that’s next to your home at all. However, you do have a limited amount of space. You can level that up, however.

To maximize your garden, you’ll then want to complete the 'A Return to Shopping’ side quest, which is also only available in the first half of the game. This one comes from the Florist Shopkeeper in your home village. As a result of this, you get a bunch of different gardening-related items - and increase the size of your garden, allowing you to plant more seeds and therefore get a greater yield.
In the second half of the game, you can unlock the garden, the expansion, or both by purchasing the Cultivator’s Handbook item from the village florist; it costs 5000 Gold. You only need this if you missed one or both of the quests in the first half, to either unlock or expand the garden.

In Nier Replicant gardening involves a real-time clock. That means that once planted, items won’t bloom and be ready to harvest until real-life time has passed. The garden will keep growing even when you’re not playing the game. That’s a cool feature, but it can, to be honest, make things a little bit difficult… especially if you’re hunting that Legendary Gardener achievement.

Items you can plant can be purchased from Florists and Grocers, found out in the world, and sometimes also drop from enemies. The various gardening plant items can be split into two different categories - seeds for flowers, and seeds for fruit.

The items you get as a result of both types can often be spent for things like health restoration, but they’re also commonly required for side quests. You’ll often have to harvest to get those items to complete certain quests. They can be sold as well - and turning over a constant flow of flowers in your garden is a great way to make money for weapon upgrades.

Vegetables:

• Bean Seed
  
• Bell Pepper Seed
  
• Eggplant Seed
  
• Gourd Seed
  
• Melon Seed
  
• Pumpkin Seed
  
• Rice Plant Seedling
  
• Tomato Seed
  
• Watermelon Seed
  
• Wheat Seedling

Flowers:

• Dahlia Bulb
  
• Tulip Bulb
  
• Freesia Bulb
  
• Red Moonflower Seed
  
• Gold Moonflower Seed
  
• Blue Moonflower Seed
  
• Indigo Moonflower Seed
  
• Peach Moonflower Seed
  
• Pink Moonflower Seed
  
• White Moonflower Seed (Lunar Tear)

To get Hybrid Flowers, you need to plant seeds of different types next to each other in the same row. This gives a chance of cross-pollination, to produce new flower colors and seed types.

In order to get seeds, you need to let the flowers grow, bloom, and then die. When the flowers are flat on the ground, you can then harvest them - and instead of a flower, you’ll get the seeds. Watering and Fertilizer will impact the number of seeds, but not the outcome in general.

Here’s how your chances of spawning a cross-pollinated flower break down, and what seeds you’ll need to put together to do so:

Red & Gold seeds adjacent gives a 20% chance to get Peach Moonflower Seeds.

Blue & Gold seeds adjacent gives a 20% chance to get Indigo Moonflower Seeds.

Indigo & Peach seeds adjacent gives a 5% chance to get Pink Moonflower Seeds.

Pink & Peach seeds adjacent gives a ~2% chance for White Moonflower Seeds (aka the Lunar Tear).

These stats sound pretty brutal, but there are some tips and tricks you can use to maximize your chances of growing the sort of seeds you need.

You’ll be able to buy Red, Gold, and Blue seeds from the Grocery Store in Seafront.
The rest of the seeds you’ll need to cultivate, which means farming your way up the chain - using the Red, Gold, and Blue seeds you purchase to work up to Indigo, Peach and Pink - and then using those seeds to eventually get the White seeds - which cultivate the legendary Lunar Tear.

The best way to achieve results is to alternate your planting. If you complete the two harvest-related side quests, you’ll have three total rows of planting spots, each able to accept five seeds. That’s fifteen planting spots total.


After planting the seeds, they must be watered.

There is one catch to even the method above, or any other intended farming of flowers that you plan to do - and that’s the time required in order to grow seeds. You see, Nier Replicant run on a real-time clock for the gardening mechanic - which means you have to wait many real-life hours in order to grow and cultivate plants. It takes 24 hours to bloom, and 48 hours to pour out the seeds.

One way around this, however, is to manipulate your PC clock. By moving it forward you can cheat Nier’s systems into thinking more time has passed, thus forcing the plants to grow. Just close the game, change the time, reopen it, and repeat as necessary.

In the end, what should you do:
1. Plant the seeds, water each.
2. Save your progress.
3. Move the clock forward 4 hours.
4. Load the last save.
5. Water the flower buds.
6. Save your progress.
7. Move the clock forward 48 hours.
8. Load the last save.
9. Collect the seeds.

In the video below, I'll show you how I grew my Lunar Tear. Combining the Peach and Pink seeds I got it from 6 times.
https://youtu.be/jHXOXmVTZeo
As with the 2010 Replicant version, I noticed that the generated Lunar Tear grows longer compared to the other flowers, meaning when I watered the buds, one flower is still at the seed stage. This is the Lunar Tear. I wanted to check which flower would grow out of it, so I moved the clock forward 24 hours instead of 48.

Good luck to Cultivate a Lunar Tear Flower (:

UPD: Many people report an error in the guide in getting a flower. The method given in this guide may not be the only one when getting a flower. I described my working method, with which I share.