In Eliot Coleman’s book “The New Organic Grower”, he describes an intriguing process of starting seeds. Instead of the traditional plastic containers and flats, he recommends using a tool called a soil blocker. The soil blocker is filled with “blocking mix” and presses out squares with an indent for planting your seed. I was immediately on board with this method. It reduces our plastic consumption and provides a more suitable home for our seeds (less likely to dry out and no fear of root boundedness).

Based on the size of our operation (we anticipate making about 20,000 starts for the spring/summer growing season), we opted for the professional stand up floor soil blocker that can make 12 2” blocks at a time. This is the ideal size for starting most seeds. In fact we are starting all but 4 vegetables from seed (we are direct seeding carrots, parsnips, rutabaga, and radishes).

Blocking Mix Recipe (adapted from Eliot Coleman’s recipe):

30 oz. coco fiber (we are using this instead of peat moss)

1/2 cup of oyster shell lime

20 oz. perlite (I’ve heard you can use rice hulls instead of perlite - something I am curious to try out)

Mix thoroughly.

10 oz garden soil (dug from our garden and sifted through a 1/2” hardware cloth)

20 oz compost

1 1/2 cups fertilizer mix (equal parts greensand, blood meal, and soft rock phosphate)

Mix thoroughly.

Add water. (The best advice I heard was that the consistency of the mix should resemble oatmeal - wet but not runny. I usually add about a 4:1 ratio of mix to water.)

A double batch of this mix fits perfectly in a 32 gallon trash can. Each batch makes approximately 250 2” soil blocks.

To make the soil blocks, I spread our mix out on a tarp in our hoop house with a 3 sided plywood tray ready and waiting. First, I make sure that the mix is wet enough by feeling it. Then I plunge the soil blocker into a large pile of mix, twisting side-to-side to fill it and rocking back and forth to ensure it doesn’t fall out. I then quickly and effortlessly lift the tool and scrape off any extra mix with either the side of the table/board or my hand. I then place the blocker directly on my tray and eject the 12 seed homes. The whole process takes about 30 seconds.

For our heat loving plants (tomatoes, peppers, and eggplants), we started them using a 3/4 inch soil blocker. I am not sure this is worth it. While more of them fit on the heat mats, they dry out too quickly. I think for our second seeding I will be sticking with 2” blocks. We will “pot them on” to 4” soil blocks once they get bigger. The 4” soil blockers come with built in inserts that press a 2” hole in the top of the block perfect for potting on.

I am really excited about how well this mix and method seems to be working for our seedlings. The germination rates are very high in our hoop house. We will be planting our first seedlings of broccoli, lettuces, cabbage, cauliflower, brussel sprouts, and beets outdoors early next week.