The Board of Architectural and Engineering Examiners does not license landscaping/lawn care businesses or employees; these services are distinct from the practice of landscape architecture. Depending on the services you offer, you would need to obtain a business license from your County Clerk and, possibly, a Contractor’s or Home Improvement license. If you have any questions about those licenses, you may contact the Board for Licensing Contractors at Contractors.Home-Improvement@TN.Gov, or by phone at 615-741-8307. Depending on the size and scope of the project, the design of certain structures may require a registered architect, engineer, or landscape architect. Additionally, if you will be applying pesticides or selling plants, you may need to obtain a license or certificate from the Department of Agriculture. You may contact the Department of Agriculture's Regulatory Services Division at 615-837-5150 for more information.
Another good resource is the small business Tennessee Smart Start Guide.