Research which variety of carrots that you would like to grow. It is best to stick to radish-shaped, ball, mini or Chanteray when growing in containers as their taproot is not as long as other varieties. Some preferred varieties include: ‘Romeo’, ‘Paris Market’, ‘Babette’ or ‘Hercules’. However, there are tons of different varieties to pick from and it is always fun to look through seed catalogs in the winter months to plan for spring planting. There are several seed companies that send catalog, try these for starters: Botanical Interests, Renee’s Seeds, Annie’s Annuals, Baker Creek Heirloom Seeds. There are many, many more just look for free seed catalogs online.