It's the tradition of many home gardeners to plant their potatoes on Good Friday, the Friday before Easter Sunday. But some years when Easter is early, there may still be snow on the grown on Good Friday! Generally, you'll want to plant your seed potatoes 4-6 weeks before the last frost date for you area. So in southeast Iowa, it's best practice to plant your potatoes the last week of March or early in April. This year, Good Friday looks like it will be perfect for planting potatoes!
While you could plant the potatoes that have sprouted in your pantry, for best results you are going to want to purchase certified disease-free seed potatoes from your local garden center or farm supply store. Smaller seed potatoes can be planted whole, but the large seed potatoes are going to need to be cut into pieces with 1 - 2 "eyes" or sprouts per piece. Each of these pieces will turn into a potato plant. If you'd like to see how to cut your seed potatoes, check out this video:
Once the potatoes are cut, you'll need to let the cut pieces cure in a humid, warm area for 2-3 days before planting. Curing gives the potatoes a chance to “heal over”, which prevents them from rotting when they are planted in wet ground.
When you are ready to plant, place the seed pieces cut-side-down 3-4 inches deep and 1 foot apart within the row. Rows should be spaces 2.5-3 feet apart.
Check out this article for a list of varieties that are best suited for growing in Iowa: What are some good potato varieties for Iowa?
And for more information on growing potatoes, check out this publication from Iowa State University Extension & Outreach that is free to download: https://store.extension.iastate.edu/product/5483