Seed Starting with Soil Blocks

This is my second year using soil blocks to start transplants from seed.  A soil blocker allows you to press soil blocks out of a sort of potting mix specially made to hold together on it’s own.  The benefits are that no plastic trays, which inevitably breakdown and make a mess, are needed. Biodegradable pots made out of peat or newspaper is a good option, but another reason makes soil blocks tempting.

Because the blocks are separated by air only, when the roots reach the air they stop growing. This is called “air-pruning” the roots and avoids the plants becoming “root-bound”, which is when the roots hit the side of their container and wrap around.  When those roots grow they essentially choke the plant.

There are various sizes of blockers and the plugs that make the indentations for seeds in each block can receive smaller blocks.  For example these 2″ blocks we’re using for tomatoes and peppers fit into the large 4″ blocker.  We likely will plant them out before they outgrow the 2″ block, but you never know and some people have shorter growing seasons and need a bigger head start.   We’ll be using the micro 1″ blocks for starting our greens in a few weeks.


The mistakes I made last year were to put to many different kinds of plant in one tray.  Tomatoes and broccoli have different temperature, light requirements, and germination times.  This year,  I put them together.

Last year we had a late frost and we lost most of our first planting and didn’t have enough for a complete 2nd planting.  This year looks to have an early spring, but just to be sure I’ll be starting at least 2 different batches several weeks apart to insure we have enough transplants and don’t have to buy any.

One thing I’ve already noticed that I’ll do next year is to write down what I plant in each row.  The rows are marked A-I on trays that are numbered.  I ran out of seeds for one of the peppers and had to go back and change my notes.

Also, in case you missed the video I made last year, you can check it out below.

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