Movement, color, door prizes are attention getters. Do you plan any door prizes or drawings? Will you be selling small items from your display to help defray the cost or have only the greenhouses for sale?Just brainstorming and don t know if they d apply: Seeds--seed packets are colorful. Kitchen compost or scrap saver. Flower pots. Watering cans. Colorful gardening gloves and hats. Fountain, either tabletop or larger. Windchimes. Birds in a cage. ButterfliesDisplay (for sale or not) of some of your favorite tools. Kid-sized tools, etc. attract kids and grandparents, especially.Could you cut a deal with a nursery to furnish some plants in exchange for advertising? Or with a hardware to let you use tools?Give away a flyer (could be simple, 1-page or less and self printed) about something such as best plants for kids to grow, how to make compost, etc. Or favorite greenhouse plants for beginners.It would have your company info, too.Good luck.
This doesn t exactly answer your question about how to make your booth stand out, but why not have dozens of seedlings in small pots to give away, in exchange for visitors filling out a qualifying questionnaire? These can be used for warm-calling after the show.