Just because it's the middle of summer and your garden is cranking out the produce for your table doesn't mean the end of gardening season is near. Several vegetables grow well into the fall. You can put plants in until August and enjoy delicious vegetables after the first frost - even longer, if you live in a frost-free zone. Remember, fall planted vegetables will need an average of 14 more days to mature than the same plant started in spring, due to the shortening daylight hours. Warm soil temps mean you'll want to water thoroughly before planting, and add compost or Miracle-Gro® Garden Soil for Flowers & Vegetables to the soil.
Spinach, collards, kale, and broccoli thrive in cool weather, so you'll want to plant seeds in July or August, depending on your region. (If you start with young plants, like those from Bonnie Plants, they can go in the ground a bit later.) Once mature, these hardy greens will be able to stand a nip or two of frost. Spinach will even over-winter in many areas. Harvest the others before a hard frost, though.
Late summer is also time to plant seeds for fall lettuce, another plant that can take the cold. Harvest a few leaves from the outer edges as needed; your lettuce will keep producing new leaves from the middle, and you can enjoy fresh salads deep into the fall.
Turnips are popular Newfoundland vegetables because they can take terribly tough winters. Rutabagas actually become sweeter after a few light frosts. Plant them in early August and enjoy them before the first hard frost. Plant Jerusalem artichokes in the spring, then dig up the tubers after the first frost. You can loosen the soil and mulch the area for easy access to more tubers all winter long.
Do not plant garlic from the grocery store; purchase them from a mail order catalog or local garden center. Break a garlic bulb into cloves and plant the cloves in rich soil when the weather starts to cool. They'll continue to grow over the winter and be ready for you to harvest in early spring.
Cabbage, kale, escarole, Brussels sprouts, arugula, leeks and cauliflower all have different planting times, but can grow well into the fall.