The ones you buy from a pet store are almost always Palaemonetes paludosus. They require fairly warm temps and as far as I know, can breed year round. I have successfully bred them in aquariums from wild caught shrimp from Florida.

Also, there are 3 or 4 other species that are "brackish" water species. P. pugio being the most common of them. They prefer salinities in the 5 ppt to 20 ppt but can survive in completely freshwater for varying amounts of time depending on the species. All species require brackish waters to successfully spawn as their larvae require it whereas the adults are more tolerant. I collect P. pugio by the thousands at my dad's house on the Chesapeake Bay and use them to feed my aquarium fish and use them for bait in the Potomac when fishing for BG and other sunfish. They make great bait.

Kansas does have P. kadiakensis native to it's waters. From my research they reproduce twice a year with their biggest reproduction time being spring with a smaller one in the late summer. TJ Hudson a member on here and I bought grass shrimp last year from a dealer in NE and stocked them into ponds. We're waiting to see how well our stocking did...