When making your blocks, start out with a peat-based potting soil, then add enough water to make it good and wet. It should be somewhere between peanut butter and cake batter. Since you're adding all that water, use a flat-bottomed tray or tub or pan of some sort. I have found it easier to use more water rather than less. The blocks seem to hold together better.
before and after
Seedlings that are going to be sold will be transplanted into four inch pots so they can have a really strong root system before going to their new homes. Also, putting them in pots makes them more transportable. But the ones that will be planted here will go from the two inch blocks right into the ground. This will keep my garbage can from filling up with disposable plastic pots.