I have never intentionally fall seeded garden vegetables, but I have noticed that if the spinach or lettuce seeds itself in the fall, they get a head start in spring.
Gardeners tell us there are risks to fall seeding. If the seeds become moist or the temperature gets low, the seeds may die. The seeds must be planted in dry soil so they won’t germinate. If the seeds survive the winter and come up early in the spring, frost can hit them.
Despite these dangers, you might like to seed some veggies this fall. On the Prairies, parsnips, lettuce, radishes, seed onions and spinach are good choices. Beans, peas, corn and tomatoes will not survive and should not be fall seeded. The best time to fall seed is late October or early November, just before freeze up.