Gardening help in the palm of your hand: 5 apps, phone tips

You're in your garden and notice a beautiful, new-to-you flower that has popped up somewhere unexpected — pull it or leave it? 

Or perhaps an unfamiliar garden pest has ravaged your tomato plants.  

Or you experienced the deflating discovery of a gray-white crust on the soil in your seed-starting tray.  

Where do you turn for help when you're on the go? Technology, of course.