I handle that sort of thing in 2 complimentary ways. First is my notoriously long lists include everything that I might be able to work on during this 3 month season. Second is that things that have a drop dead date have a due date added.
So your example, The Project Plant Fall Garden would be in my context outside by myself and one of the action items in it would be plant peas. The project would have a start date of July 1 (the season in which September falls) and the action of Plant peas would have a start date of 1 September and a due date of 30 September. In my world the entire project would have a setting to complete when last action item is completed and be on a yearly repeating schedule. So July comes around and perhaps the first action is plan fall garden. I'd review what I had in the project from last year, maybe review references from garden notebooks or something and then make decision what to plant, the plant peas might get more notes like see list of varieties in electronic action support which might be a list of mail order places to get seeds or whatever. If I decided not to do that at all I could easily reset it to next year.
Because the project is active from July to September I'll be reviewing it weekly that whole time and easily see what I need to do to decide to move it forward, or not.
