Auto watering project help/advice

Hi everyone! I’m working on my project “Auto watering” I’ve made general work for that and it is already working but I want to add a sleep mode. General task is to wake up from sleep mode, make moisture measurements and then based on measurements, water plant. I’m going to use salad as plant, and I need the microcontroller to wake up twice a day. Also I want the microcontroller to wake up from external impact ( button)

So, what do you think is the best way to wake up microcontroller?
I’m going to use WatchDog timer but I don’t know how to do that yet.

I’m hoping to get your advices! Thank you in advance!!

What microcontroller are you using?

Arduino uno. Atmega 328P