I live in Tucson, and scorpions are a way of life here. One good product you can buy over the counter is Raid Spider and Scorpion spray. It works very well. Whenever I'm doing yard work and may encounter a scorpion, I wear heavy leather gloves. They do a good job of protecting your hands. The majority of scorpions we see are during the rainy season when they are thriving. I don't think watering the plants will affect them much.
The scorpions you are describing are probably bark scorpions. They can be dangerous, but for most adults, it just hurts like hell when you get stung. I've been stung several times over the years with no ill effects. Folks with health problems, elderly and kids should seek treatment if they get stung.
