This chart gives a general overview of what's ready when, but timing can vary from season to season…

  June July Aug Sept Oct
Arugula June July   early September through October
Asian Greens       early September through October
Basil   July August    
Beans   through late September through late September early through end of September  
Beets   late July through late October late July through late October late July through late October late July through late October
Broccoli     late August September October
Cabbage late June through late July   mid September through late October
Cantaloupes     early August through mid September  
Carrots   mid July August September through October
Cauliflower       mid-September late October
Celery     August   October
Cherry Tomatoes   mid July August    
Collards June July August September October
Cucumbers   July August    
Eggplants   mid July August September through mid October
Garlic   mid July through mid August    
Herbs mid June July August September through October
Kale June July August September October
Lettuce June July through mid August early September through October
Mustard Greens       September October
Onions   mid July August    
Peppers   late July August September through mid October
Potatoes   mid July through mid August mid September through mid October
Radishes June through mid July   late September through October
Spinach June       and October
Sugarsnap Peas June through early July      
Summer Squash   mid July August through early September  
Swiss Chard June July August September October
Tomatoes   mid July August September through mid October
Turnips mid June through early July   mid September through mid October
Watermelons     early August through mid September  
Winter Squash     late August September through October