Soil Blocking


I am writing this on the second day of spring with a nice white blanket of snow covering everything, by the time it is posted on Friday everything will be a muddy mess. Today's snow day was spent starting seeds. We are in week 3 of our seed starting schedule and I thought I would share with you what our process looks like.

I use a method called soil blocking, I don't know if this is something that I will always do, especially as we grow because it is fairly time consuming but it also has some great benefits. One huge benefit is that you can fit a ton of seedlings into a very small space. We are able to start 4,400 seedlings on a 5 tier rolling rack, it measures 18 inches deep and 48 inches wide. Another benefit of soil blocking is that the plants seem to be healthier, they do not become root bound from being in a container.

The first thing I do is measure out the amount of soil blocking mix and proportional water, usually a 3:1 ratio. There are several options for blocking mix, the best I have found is from The Gardener's Workshop. This year we are using a different product called ProMix BX. After our first two seeding rounds I was not happy with how the blocks were holding up, (I had been warned about this but was trying to watch my costs), this week I added peat moss to the mix and am hoping they will hold better. You are aiming for an "oatmeal" like consistency, not to wet, not to dry but "just right".

Next I take my blocker (I ordered this one from Johnny's) back and forth into the mix and gently press along the bottom and scrape off the sides with a rubber scraper. Then you dispense it onto the tray and "wa la" you have twenty 3/4" soil blocks. I use cafeteria trays and am able to fit 220 per tray.

I then place the trays on heat mats and cover with a plastic dome until about 50% of the seedlings germinate at which point I will transfer them to the grow lights.

Soil blocks do dry out very quickly because they are so small so they must be watered every day. I typically aim to have them planted out into the field 3-4 weeks after I sow them. We really had great success with this method last year and I am excited to see how this year goes.


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