Here's an idea for anyone who yearns to start growing food before the ground can be worked in March.
We've harvested four big bowls of cool-weather greens in the last couple weeks. With Chicago's temperatures swinging wildly between 80 and 40 F, the greens alternate between getting a shot of growth-spurring heat and the cold they thrive in.
This picture was made April 26 (the SIPs look a little light since I've started regularly cutting for meals). Greens deliver near-instant gratification. When you plant a tomato, it's an act of faith that two to three months later you'll be reveling in flavor.
The Red Velvet lettuce from Seed Savers below is just coming into its own. I wonder if it will ultimately produce the very dark red lettuce shown at the link.
It's a thrill to stop buying organic greens shipped in from California (though we're lucky to have access) and instead tuck into a bowl of 12 different chards, kales, lettuces, mustard, arugula, and cress, chopped and doused with the house dressing: olive oil/Dijon/chardonnay. These young greens are so tender they don't need steaming.
We're lucky that Bruce started our cool-weather plants under lights, so they'd settle in and start producing quickly. The direct-seeded versions in our tiny in-ground garden bed are lagging behind a bit.
It's worth noting that anyone who wants to try growing in SIPs, including earthboxes, can start these beauties from seed inside in February before planting and setting them out in late March/early April. In Chicago, this extends our growing season by at least 6 weeks and generates a steady supply of phenomenal green food.
Next year I think we'll try starting even earlier...