Coleman uses a soil block maker that he developed for Johnny’s Selected Seeds ($22 to $170 depending on the size). This is a mold that forms the wet growing medium into cubes. You can use different sizes to contain seeds of varying sizes.

Make a blocking mix that will hold together but not harden out of peat, sand, soil, and compost. Coleman uses the following recipe to make a large amount of mix at one time.

• Start with three 10-quart buckets brown peat.
• Mix in 1/2 cup lime.
• Add two 10-quart buckets coarse sand or perlite and 3 cups base fertilizer, and mix together.
• Add one 10-quart bucket soil and two 10-quart buckets compost, and mix thoroughly.

A seed or cube pin makes the indentation to hold each individual seed or small seedling. You can use interchangeable types of pins for different plant varieties and sizes.

Coleman recommends a modular system so that seeds can be started in smaller soil blocks that then fit into large blocks as they grow and require more root space.

Place each small seed plug into the larger blocks until you have a full tray. Coleman recommends an open-sided tray so that the blocks are easy to scoot off for planting.

Keep the soil blocks watered with a mister, fine rose can, or hose until planting time.

The Four Season Farm greenhouse is full of dozens of healthy lettuce seedlings. And not a plastic pot in sight.