Growing Irish Potatoes or other varieties is really an easy crop for Parker County. From my experience, seed potatoes are purchased from the local feed store (do not use potatoes from grocery stores, as they have a growth inhibitor on them) around the first part of February.
Around the 10th cut the potatoes into quarters and let dry in a dry, fairly cool place. Some people like to place them in a paper sack or on newspaper. I always plant my cut up potatoes on or around February 14th. Your crop is ready when the top growth begins to turn yellow and then brown. 'Digging' potatoes can be a fun activity for the entire family. The link below will open a PDF file that will supply you with all the info you will need to have a successful potato crop.
Easy Gardening of Irish Potatoes by Joseph Masabni, Asst. Prof. Texas A&M Univ.