The January/February 2012 issue of Chicagoland Magazine features planning guides for the year for annuals, shrubs, and vegetables. I found the vegetable guide particularly helpful; between starting seeds, planning for cold crops, and continuous harvests, all those dates can become confusing! Caught up in all of the excitement going on in the garden in late July, for example, I always miss the indoor sowing time for the cold fall crops like broccoli, and they are always sold out of the garden center by then.
Pick yourself up a copy and check out page 52 and 53. There is also space to add in your own items, so you can maintain a comprehensive to-do list for the year.
By the way, don't start your tomatoes and peppers until mid-March!