To provide a precise answer, I'll need more context regarding the diagram you're referring to, as well as specific details on how the values for "in" and "main" are defined in relation to the garden plot. In statistics, "n" typically refers to the sample size used to estimate a population total, while "main" might refer to the main category being measured or analyzed.
If you can describe the diagram or give me more detailed information about the data related to the seeds in the garden plot, I would be able to help you calculate or estimate the value of "n."