Kelly Green – Garden Queen is a time management game where players must help Kelly in fixing up and organizing a nursery that she inherited from her grandparents. The player starts out by purchasing seeds to be sold to the customers. There is a variety of seeds available, depending on the season. Kelly takes orders from passersby and through the phone. Once an order is placed, players must help Kelly deliver them to the correct customers before their patience runs out. Customer patience can be increased by serving them lemonade while they wait for their orders to come. Customers order flower arrangements so players must ensure that different kinds of flowers are available. Planting can be done inside the greenhouse or out in the garden. At the end of each level, players are awarded a ribbon, a silver cup, or a golden cup.
There are also challenges along the way, such as birds and bugs that destroy plants. Kelly can get rid of them by purchasing a cat, providing a home for the bugs, and pitching a scarecrow. These are available in the game store where other items, such as nursery upgrades and seeds can be bought. The game features 20 different types of plants and flowers, and 50 kinds of garden equipment to purchase.