Question about breeding white and yellow roses

[Sicariana]

I am following this guide to breed blue roses. One of the steps involves breeding seed white (rr-yy-Ww-ss) and seed yellow (rr-YY-WW-ss) roses together.
The offspring is 50% yellow (rr-Yy-WW-ss) and 50% white (rr-Yy-Ww-ss).
How should I organize my roses so that I know each white that appears overnight is of genotype rr-Yy-Ww-ss as opposed to rr-yy-Ww-ss? Do I just need to ensure that no two white roses are touching? I heard that ACNH uses a 5x5 grid as opposed to a 3x3 grid so I am confused.

 

[meggiewes]

It should be as easy as planting a white rose and a yellow rose beside each other. The offspring should have white genes and yellow genes from the parent plants.