I created a DateTime helper for watering our plants every 7 days, and an automation that triggers every evening around dinner time that checks the timestamp in the helper, notifying me to water them if the date has passed.

Whenever I water, the smart switch on the water pump triggers another automation that resets the helper's value to "now + 6.5 days". So I always get the reminder on the 7th day, and if I skip it, it'll nag me the next evening, and the next. If I water a day early, next week I'll get the reminder a day earlier, because it's been 7 days.

Someone recently posted the brilliant observation that NFC tags can be used to track your chores. So now I'm planning to slap an NFC tag on the furnace and create another helper to remind me to change the filter after 90 days. Eventually I can put NFC tags on all the things that need periodic maintenance, and just wave the phone at them when they're done.

Since this seems like a thing that can quickly expand, I'll have to figure out how to rework the automation scripts so I don't have to create two new scripts for every chore. But that's a problem for future me.