We've got an app for that! Actually we've got a couple of them.
In the new pumpkin patch I'm putting in a little technology to make things easier and better. When we moved to the new house the outdoor temperature gauge was broken so I hoped on eBay and found a new one (open boxed special). This one has three wireless sensors and has an app that allows me to check the temperatures from anywhere in the world. I'll use these in my hoop houses to make sure it isn't getting too hot or too cold. It will even send me alerts if it goes below a certain temperature or above a certain temperature. Right now I have one in my grow closet, so I can monitor the temperature for my plants. It is a very nice 84.2 degrees currently.
I'm also using the PlantLink soil monitoring devices this year. I actually got them for Christmas over a year ago, but since I didn't grow last year I didn't use them. These wireless devices monitor soil moisture and give specific recommendations based on weather and type of plant. From what I can gather I'll want to be on the high side of their recommendations. It also has a phone app that will allow me to watch the watering while I'm away. At one time they were going to come out with some valves that you can remotely turn the water on with, but I've never seen them for sale.
I got the PlantLink after in two different seasons I had watering problems. One year the pump on the well stopped working and the plants got dry and my big pumpkin got a dill ring three days later and split shortly after that. Last year my timer wasn't working right and I didn't know it. The result was the plants were getting watered for a week about 1/10th of what they should have and the plants got damaged.
PlantLink seemed like a really promising company a couple of years ago. They were bought out by Scotts and seem to have gone kind of dormant since. As long as I can get some kind of indication for where the soil moisture is at I'll be happy to use it to help perfect my watering.