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Potting Up!

It has always bothered me to use those plastic inserts and trays when planting in the greenhouse, (although a couple years ago our friend George gave us stacks and stacks of used trays from an old greenhous operation. It somewhat assuages my guilt to have recycled these more than once…) The bottom trays are ok as they’re made of a relatively durable material compared to those thin and cheesy inserts which seem to be getting thinner and cheesier by the year.  

So this year, we’ve invested in a set of soil blockers from Johnny’s Seeds. (They have cool hand tools — and we take our tools seriously. This year we’re adding a new broadfork, seeder and lettuce harvester, and a 5 gallon salad spinner…how to make a farmer happy!)

We got two block makers, the 2″ blocker that makes 4 cubes and a single large block, which forms a corresponding cube-shaped indentation for potting on of the smaller blocks. So, for example, when it’s time to pot on the tomatoes, you just plop them into the waiting larger cube. No fuss, no muss! According to Eliot Coleman of Maine, (farmer and author of Four Season Harvest, The New Organic Gardener, and Winter Harvest, etc.,) the seedlings grow so much better in blocks than in conventional pots. In the blocks, the roots grow to the edge, and there they stop, waiting until they’re planted on, or put into the ground.  Commercial soil mixes for blockers is available, but it’s so much cheaper to make your own. (Recipe for the mix below.)

Ross and Rich add water to the soil mix.

Here’s the recipe for the starting mix from Eliot Coleman’s book: The New Organic Gardener

The three ingredients in the fertilizer mix

Based on a 10 qt. bucket as a measure. Mix well after adding each ingredient.

Coarse sand (cheaper, but heavier,) or you can use vermiculite.

  • 3 buckets of brown peat
  • 1/2 cup lime MIX


  • 1 bucket of course sand
  • 3 cups basic fertilizer mix (based on equal parts greensand, rock phospate, and blood meal)
  • 1 bucket loam or garden soil
  • 2 buckets compost

We put about 8 shovelfuls in our wheelbarrow and using a hoe, added a little water at a time to wet it, like mixing mortar. The mix is a little wetter than you might think. Experiment. We found that you get better blocks if you push the mold into the soil more than once to pack it really well and push out some of the water. Just like making mud pies!



Ross packs the wet soil into the 2" x 4 blocker

Once we got a system down, were able to make up about 12 flats in an hour. Definitely well worth our time.

The handle on top is on a spring. Push to release the blocks into the trays.


12 flats in an hour. What's 12 x 36?


Suctions holds the soil in when you have the mix right.


The larger blocks make a 2" depression for potting on the smaller cubes.

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