The early garden I plant is very small, and mostly just to have something fresh to eat after a long winter. Spring up here is extremely unpredictable and it is not wise to gamble too much. Extending the growing season in the fall is much more productive up here. The soil is already warmed, and is easier to keep at an acceptable level, than the very cold, often frozen spring soil. When the average time ( up here) between eating a fresh tomato in late summer, to eating the first fresh tomato the following summer is 10-11 months, extending the season, when the tomato's are already formed, makes the most sense.