Many common crops that thrive in cool weather immediately bolt, or go to seed, in the heat of summer: lettuce and spinach are prime examples. They do well as long as the soil and air remain cool in spring but must be pulled up once things heat up. Other crops that thrive in cool temperatures are beets, peas, carrots, and leafy greens such as kale and chard. All of these can be grown in fall as easily as in spring.
To grow a fall vegetable garden, you need to know two things: your estimated last frost-free date and how long a given crop takes to mature. For example, suppose your average date of last frost is October 15 and you want to grow beets, which take approximately 60 days to mature from seed. Count back 60 days from October 15: you can plant beets any time up to August 15. If you want to grow lettuce, which take only about 45 days, you can start as late as September 1. Some crops, such as radishes and mustard greens, mature so quickly that you have time for several fall sowings.
This article on growing fall crops give you the approximate number of days to maturity of many common crops, as well as other useful information. If you don’t know your USDA plant hardiness zone, start here. And note that the map was updated in 2012. If you are quite sure that you’re in Zone 6, you might be surprised to find that you’re now in Zone 7.
When the weather cools down later this week, I’ll be weeding the vegetable bed, removing spent crops, and planting lettuce, beets, and maybe even some snow peas.