They are only 2 months old. What is the growing season for Iowa? I was looking at a harvest before October if possible, because we can have snow. Also they are getting very tall and I am worried about someone seeing them. Any way to make them stop getting taller ?
Too soon to tell, wait until like mid-July to August. Some plants show preflowers in May but some you can't tell for a while.
In that amount of time they could be 6-7 feet tall. Should I tie them to a fence to slow down growth ?
That depends; do you have neighbors, and how tall is your fence? There are lots of guides to training your plants to be short. You could top/fim them, or try tying them down so that it's practically horizontal. Don't do it all at once, but I think the idea is to take a stake and put it next to your plant, carefully bend it as far as you can without breaking, and tie it to the stake. Every week bring it down another inch or however far it'll go, and it'll adjust.
Yeah man, try the LST shit... just start bending the plant and tying it down as it grows.. you'll be set with a nice amount of bud off that plant for sure.