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For most Extension offices in most states, they have a variety of gardening curricula, depending on the state. Almost all states have a Master Gardener Program, which tends to be a pretty intense gardening training (14 weeks in Michigan) with a volunteer component. Not everyone wants to make that commitment; although it is an excellent program!
On a more introductory level here in Michigan, I co-teach a "Vegetable Gardening 101" series, which is a shorter vegetable-based 6-week series. Those are live webinars, and we just completed or two series for the year in April-so very sorry that you missed them. We are, however, looking to make recorded versions of those available year-round, but those are not ready yet.
There are, however, many topic-related online classes that can be viewed for free any time of the year. See:
I am also working on a "middle-ground" vegetable curricula with a co-worker, which is somewhere between our intro vegetable gardening series and the Master Gardener Program. Again-not quite ready!
Michigan has many resources available for home gardeners, such as our Smart Gardening Tip Sheets https://www.canr.msu.edu/home_gardening/tip_sheets/
There is a M-F Gardening Hotline with a Master Gardener or MSU Educator on the line, live, to answer questions: 1-888-678-3464.
Feel free to email me directly for any more questions: