[rrosen326]

If you're talking outdoor plants, this thing is great: https://www.rachio.com/

(If indoor, overkill.)

[spapas82]

Well this is way too fancy (and expensive) for me. I am using a good old Claber system which costed ~ 40 euros with the hoses and drips: https://www.easywatering.co.uk/claber-products/automatic-wat...

It works perfectly (watering the plants 1-2 times a day depending on the setting I set); I like its simplicity and easy of use!