We will be on vacation from July 6 - 13. The in-ground stuff should be mostly ok, but we have potted plants on our deck.
Wife thinks I’m insane that I don’t really trust our pet sitter to water them properly. I envision either drowned plants or bone-dry, crisp ones when we get back.
Offer a bonus for live plants
Put them next to the Sprinklers and water them for 15 minutes daily and that is your best bet.
5-gallon bucket of water with a cup measure beside it. Tell them how many cups each plant gets and how often. (Actually, doesn’t need to be a cup but a handled measure/scoop of appropriate size) Hard to mess up here, unless they completely forget. You can write it out with a check list that anyone could follow. 
My wife says my check list is annoying and too much for them to read.
That doesn’t sound like a list problem, it sounds like personnel problem.
Try one of the watering balls
Set up a drip irrigation system with a battery operated timer! That’s the best source and dependable you can pay with your check!
I just went through that a few weeks ago and I almost lost a few fig trees because of that. Now I know what I need to do on the future.
Can’t trust anyone else to water the potted plants. If it is in summer time, I set up a simple irrigation system and put them on timer. This will take care watering, although if it keeps raining then you might still have problem
I know, I should get a timer… But I’m a bit gun shy. A couple years ago, I had a timer that turned the water on, but never shut it back off. I got home to find that the sprinkler had been running for about 14 hours straight.
Oops.hope water bill wasn’t big
I would get one of these:
https://www.amazon.com/gp/product/B004INGS8S
I’ve had three of them so far and they work really well. Never had an issue with water not shutting off, I think thats more of a problem with mechanical timers. Just make sure that you bring them inside before your first frost date or they will crack and start leaking.
I uses to lose 2-3 plants everytime we went out of town, no matter the preparation
I plan my travel in the wet spring now and tgus is far leas of an issue.
Thise polymer crystals can be very helpful in situations like these, though.
Scott
That’s what failed on me.