The following persons and activities are exempted from the provisions of this chapter: Any architect registered under the provisions of chapter 390; and any professional engineer registered under chapter 391. Nothing in this chapter shall prevent a vendor of goods, services or materials, including nurserymen, landscape nurserymen, gardeners, landscape gardeners, and general or landscape contractors, from providing drawings or graphic diagrams necessary for the proper layout of his goods or materials, or prevent a landscape designer from engaging in, for a fee, the design of spaces utilizing plant materials and incidental paving and building materials or arranging for installation of the same. Nothing in this chapter shall be construed in any manner to prohibit any person from making plans, drawings, or specifications for any property owned by him. Notwithstanding the provisions of this section, any person exempted under this section or any persons engaged in activities exempted under this section shall not use the title “landscape architect” unless such persons comply with the provisions of section 20-369.