Yes, potentially, as a manager of an essential function if the chart and the record of his decisions show senior-level discretion over production and sales, with seasonal supervision delegated to crew leads. Headcount alone does not decide it.
Function management is recognised; working supervision is not
The regulation's definition of managerial capacity has two branches. One is managing the organisation or a department through subordinate supervisory or professional employees. The other is managing an essential function at a senior level with discretion over its daily operations.
A greenhouse general manager who sets the production plan, negotiates buyer contracts, approves capital spending and hires the crew leads fits the second branch even with a small permanent staff, provided he is not himself the person directing the pickers most of the year. The deciding record is the organisational chart with the seasonal layer, supported by a dated list of decisions and by payroll showing that crew leads exist. If in truth he spends the growing season on the floor and the function is managed jointly with the owner, the case is weak, and it is better to say so before paying the petition fee than to build a chart that the business cannot live with at an interview.