For starts i will release it once every 2 days, then i will add monitoring to see the levels of moisture in the soil and such, to release it based on that.
I would like to find a way to press the button on this cannister once every 2 days. I am not looking for the programming part, but for the actual device that will hole this cannister and spray it. I thought to use a 5V relay and open/close it for eg 5seconds. What about the device that will put some pressure in order to release the pesticide?
Print a 3D carrier to fit the can, and add a lever mech to press the nozzle.
The good news is that it only takes maybe 2-3mm of travel, so you can get a bunch of torque & pressure from the servo arc.
How much current is available? A simple solenoid pressing the button should work well. Naturally, you'd need a driver of some sort (mosfet, electromechanical relay) between the Arduino and the solenoid
Air Wick, Febreze, Glade and others manufacture bathroom air fresheners that after a given time release a spray mist. Not my department but the wife just orders cannisters using Amazon. Fully automated and programmable. Going to Amazon and searching Air Fershner Spray Automatic will give you plenty of results. Just find one and hack it to see exactly how it works. Then figure out a cannister and how to charge a cannister. This is where I would start since it's already been done.
