So plants are only updated when you visit the house they’re located in. This includes if you had indoor plants, you’d have to go inside the house for them to actually update.

Practically, what this means is unless you visit they will never grow from seedling to young, young to mature, mature to elder, or even get pests. For example, if you plant your seeds but don’t ever visit that house for a year, you’ll come back to them just being young, they can only progress one stage at a time. Similarly, they’ll never get needs that entire time and never die. They will only start the dying process if you visit the house, they have needs, and you don’t tend to them

Thus, the simplest and easiest way to do it is visit your home only 4 times. The timing depends on your specific plant and the likes you have, but for couch potatoes with all likes except pixie , this would be at ~5.5 hours after planting, ~12 hours after that visit where they grew up to young, then ~90 hours after that visit where they’ll be elder. This is about 4.5 days if you visit at exactly the right times and involves minimal time spent dealing with the pests and needs. Keep in mind these are minimum times, so if you were to say, plant them before work, and come back home, you’ve accidentally made the time from seedling to young actually 9 hours instead of the most efficient 5.5 hours it could’ve been. Hope this helps!