Vegetables to plant in August in the Northern Hemisphere include cool-season vegetables, such as kale, broccoli, spinach and onions. Lettuce and peas are also cool-season crops for a gardener in the Northern Hemisphere to consider planting in August.
Other cool-season crops include carrots, beets, Brussels sprouts, cabbage and cauliflower. Asparagus can also be planted, but it takes two seasons before it's ready to be harvested in early spring. Artichoke is another option to plant, but it also takes a while to be ready for harvest.
Gardeners who live in the Southern Hemisphere can consider planting warm-season crops, such as tomato, eggplant, squash, cucumbers, corn, peppers, green beans and potatoes, in August.