We begin thinking about any spring planted crop the previous fall. Since springs tend to be cool and wet, all field preparation is best done in the fall. Field preparation may include chisel plowing for deep tillage, rototilling to help break down crop residue from the previous vegetable, laying down beds of black plastic, and coordinating and planting a winter cover crop to build soil health. While we try to use cover crops as much as possible, some of our fields are planted so early in the spring, perhaps with peas, carrots, or spinach, that there is no time to deal with the residue of a cover crop. These beds are then prepared in the fall but left bare for the winter.
Once our fields are prepared, we either direct seed or use transplants we've started in the greenhouse. If there is a week in mid-March when the ground thaws, Derek makes sure to get peas, carrots, and spinach seeded. These vegetables can germinate and survive even if cold weather returns with hard frosts. However, growth is very slow in the cold.
Transplanted crops give us a jumpstart, sometimes with nearly two months of growth. In our warmed greenhouse, we don't have to worry about cold temperatures inhibiting germination: little plants will pop up and grow steadily. Sweet corn germinates earlier than it would in the field and much more uniformly. It may seem odd to think of transplanting corn, but by using transplants we also avoid an early spring insect pest. Seed corn maggot is a juvenile of a fly very similar to the house flies you are familiar with. The maggots are active in very cool soils and they prefer to eat the large seeds of corn, beans, and peas. Since cool soils also slow the development of our vegetable seeds, often the maggots destroy the viability of the seed before the plants can emerge. Corn and bean transplants completely sidestep this hurdle.
So now that we've got little seedlings, and somewhat bigger transplants, growing in the fields, how can we protect them from freezing night time and cool daytime temperatures?