The Shamrock Farms Tour takes place at the farm in Stanfield. For those people living in Chandler, or Ahwatukee, or other locations near I-10 south of Phoenix, it will take an hour or so to get there. For those of you living in Surprise and Fountain Hills, it might be considered a day trip!
To get to the farm, take I-10 to Queen Creek Rd. exit. Turn right onto Maricopa Road (Route 347) and continue south for 15.5 miles. (If you are coming from south of Queen Creek Road, you can take Riggs Road out to Maricopa Road, Route 347, and then make a left.)
In Maricopa, turn left onto Maricopa/Casa Grande Highway. There will be a blue Napa Auto Parts store on your left. If you go over the railroad tracks, you've gone too far. If you get to Harrah's Ak-Chin Casino, you've really gone too far! Continue east on the Maricopa/Casa Grande Highway for 3.5 miles. Turn right onto White & Parker Road (there's a big sign reading "Pinal Feeding Co."), cross over the railroad tracks, and continue south for about 9 miles. Turn right onto Clayton Road at the Shamrock Farms entrance sign.
However long you decide it will take to get there, add at least another 15 minutes! You don't want to miss your tour, and there's plenty to read and learn while you are waiting. I estimate that from I-10 and Queen Creek Rd. it takes about 45 minutes.
Roxie told me this, and she said I can tell you: Do not use an online mapping service to get directions to the farm. That will only make matters worse.