Coordinating a community garden without turning it into a spreadsheet job

Our garden has twelve volunteer roles, changing weather, and people who prefer different kinds of work. I would love a lightweight workflow for reminders, swaps, and a public record of what was planted.

Keep the public record event-sized: task offered, person accepting, completion, and one note for the next visit. Weather can trigger suggestions, but volunteers should always be able to swap without explaining private circumstances.