NieR Replicant ver.1.22474487139...

This is by far the most time-consuming trophy in the game. When done legitimately, you'll be looking at a minimum of 168 Hours for this trophy alone, and it's just a whole lot of waiting around. That method is listed below. It follows along the same instructions as Shadow's original method, but you can't manipulate the clock in the same way as the PS3 version. If you're looking for any sort of clock-manipulation method, our friends over at PowerPyx have allowed us to link their method to getting this trophy done in ~48 hours versus ~168, so please follow the link at the bottom for that method (credit goes to Gage for spending a ridiculous amount of time figuring that method out).

The Legendary Flower is the White Moonflower, which you'll need 3 full growing cycles and 1 partial cycle to get. To get the White Moonflower, you'll need to spend a lot of time cross-breeding other colored Moonflowers until you get to White. 

The time stages for the flowers are as follows:

You will, of course, be needing seeds for the first 3 Moonflowers you'll cross-breed/create. So 48 per. 

When you have your Pink and Peach Moonflowers, you'll need to cross-breed those in hopes of getting a White Moonflower. 

Now, obviously the more seeds you have at your disposal, the better chance you'll have to get this done in timely-manner. To cross-breed flowers, you need to have their horizontal positions alternating (horizontal being the same row of dirt). If your garden is fully expanded, each row will have a total of 5 available spots to plant on. You can pick up some Speed Fertilizer from the vendor in Seafront, but please note that this will only cut the growing time in half for the flowering part, not the actual seeding part.  

Starting with trying to get the Peach Moonflower, you want to purchase 9 Red Moonflower Seeds and 6 Gold Moonflower Seeds, then plant them so the horizontal rows are alternating:

Red - Gold - Red - Gold - Red
Red - Gold - Red - Gold - Red
Red - Gold - Red - Gold - Red 

Save your game at the nearby mailbox so if you have to come back to this step, you can. Go back to your garden and water all of the seeds and put Speed Fertilizer on them if you have it. Also make sure you water all of the plants to potentially increase the seed output. If you used Fertilizer, you'll need to wait 12 real-time hours for the flowers to bloom. If you didn't, you'll need to wait 24 real-time hours. Once the flowers have bloomed, you hopefully have 1 or 2 (or more) that have bloomed into Peach Moonflowers. If you don't have any, reload your save, pick up and replant the seeds, and try again. After the first 12/24 hours, if you're satisfied with your blooming, you'll need to wait an additional 24 hours real-time before the flowers can be harvested for seeds. When they're ready, harvest the seeds. 

Now you need to move on to the Indigo Moonflower. You'll need 9 Blue Moonflower Seeds and 6 Gold Moonflower Seeds. Place them just as before, alternating on their horizontal line. 

Blue - Gold - Blue - Gold - Red
Blue - Gold - Blue - Gold - Red
Blue - Gold - Blue - Gold - Red

Repeat the process of waiting/fertilizing/watering, then waiting again for the seeds to harvest. When you have a few of the Indigo seeds, you can move on to the Pink Moonflower Seeds. For these, you'll need 9 Red Moonflower Seeds and 6 Indigo Moonflower Seeds (if you want a full garden, at least). Place them just as before, alternating horizontal rows:

Red - Indigo - Red - Indigo - Red
Red - Indigo - Red - Indigo - Red 
Red - Indigo - Red - Indigo - Red

Repeat the process again until you are able to harvest Pink Moonflower Seeds. Now for the final step, cross-breeding the Peach and Pink Moonflower Seeds. Place them just as before, alternating rows:

Pink - Peach - Pink - Peach - Pink
Pink - Peach - Pink - Peach - Pink
Pink - Peach - Pink - Peach - Pink

With a little bit of luck, after the first 12 (w/ fertilizer) or 24 (w/out fertilizer), you'll have at least one White Moonflower ready for harvesting. You don't have to wait for the seeds to be ready for harvesting, just the flower itself. Go ahead and pick it up and when you do, the trophy will unlock. 

If you're looking for a quicker, more time efficient way to get this trophy by manipulating the timezone settings on your console, please see Gage's guide over on PowerPyx's site that walks you through how to properly setup this trophy and earn within about a 48 hour period: Powerpyx's Legendary Flower Guide