While many gardeners think of August as harvest season, it’s also planting season. August is a great time to sow broccoli, kale, radishes, peas, spinach, lettuce, arugula, and other cool- season crops. These vegetables often grow better in cooling autumn weather than in spring. Some even become sweeter. Kale and turnips, for example, convert starches into sugars as temperatures drop. So while you're picking tomatoes and beans, don't forget to save space for a second season of harvest. The challenge is to keep the seeds moist in the warmth of August air, until they germinate.
Growing Home - August Vegetables