Soil Blocker Revisited

Soil Blocker Revisited

Clear As Mud

Let me back up a little bit. A couple of days ago I posted about my recent acquisition of a soil blocker and the recipe for the soil mix that I use to make the blocks. Since then I have gotten several questions about blocking, the recipe and the reasoning behind a decision to adopt the practice in the first place. So let me start in the beginning…

Read->>How to Use a Soil Blocker and DIY Soil Mix

Seed Starting Needs

When you have made the decision to start your own garden seeds, you have several ways to go about it. You can sow your seeds directly into the garden, then wait anywhere from a few days to several weeks for the seeds to germinate before anything starts to grow. For a few crops, like carrots, this is the only way to go because of inherent risks associated with transplanting seedlings. There are other crops that, for most of us, require transplanting because of the length of the growing season, germination requirements or other factors that make these crops a bit more touchy. There is also a large group of plants that can go either way, depending on what you are trying to achieve. If you are only starting a handful of tomato and pepper plants per year, soil blocking may not be terribly appealing. On the other hand, if you start a lot of seeds for transplanting it can make sense to use a soil blocker.

Soil Blocker Revisited

Blocking Versus Other Methods

  • By not requiring a pot, there is a cost and storage savings.
  • Soil blocking mix may be purchased ready-made or mixed on site with readily available ingredients.
  • Instead of forcing roots to the pot wall where they begin to wrap around the rootball, soil blocks (like peat pellets) force roots to develop within the soil, making them less prone to root damage and faster to get established when planted out in the garden.
  • The soil mix used in blocking is far superior to peat pellets or conventional “seed starting mix” because it steadily feeds the plants from the beginning.
  • True it is common practice to use a mild liquid fertilizer with conventional seed starting, but this extra step is eliminated because of the plant food in the blocking mix.
  • The blocks fit more closely on the tray than do round pots or pellets, and blocks have greater volume than do cylinders. Spatially you can fit more plants with greater root volume per plant, compared with round or tapered pots.
  • Although I have not purchased the other blocker sizes, blocking offers a method to “pot up” small sized blocks into larger blocks so that plants may be held for longer periods before planting out.

Blocking Increases Production

If your goal is to maximize garden production, using the soil blocker can help. It combines the greater control that indoor seed starting offers with increased vigor that is the result of well developed roots with less damage. You can harvest one day and set out well started plants the next, decreasing the interval between crops by weeks. Vigorous plants are less susceptible to disease and insect damage, further increasing success.


Questions On The Recipe

The blocking mix recipe I used is for small batches such as most of us would use. If, however, you want to do one large batch for the season, you might want to use a larger vessel for each “part”. If so, calculating the “handful” of lime as 1/8 part, and the 3 cups of Sure Start as 1/4 part should get you in the ballpark.

I buy peat moss in a compressed bale of 2 cubic feet and the vermiculite comes in a 2 or 4 cubic foot bag, both widely available at garden centers and home improvement stores. The lime comes in 40# bags labeled “garden lime” or “lawn lime” just be sure to get the powdered form and not pelletized. Stay away from “fast acting” lime because it’s not suitable for this application. You can either use homemade compost or purchase mushroom compost or high quality composted manure (no fillers). The garden soil is just that, soil right out of your garden (I have a heavy clay base and it works like a charm).

Read->>How to Use a Soil Blocker and DIY Soil Mix

I’m New At This Too

I would like to hear back from those of you who have used blocks. Any thoughts on the process, whether or not you have continued using them, would be helpful to the rest of us. Thanks for your comments!


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4 thoughts on “Soil Blocker Revisited

  1. I used the blocker last year to start some broccoli and tomatoes, and it worked great. One hint I use is to dip the blocker in water before each set if you find the soil isn’t releasing well. I’ve heard in the past that direct-seeded plants develop a different type of roots that help the plant survive better with fewer inputs over its lifetime. I believe seeds started early in blocks more closely replicate direct seeding than those started in containers. I use plastic dishpans from the dollar store to hold them. Does it make sense to use heat mats with these blocks, and do you have a good strategy for knowing when and how to water them? Great info, and thanks!

    1. Thanks for visiting! The plants I seeded on Saturday had germinated (90%+)by Monday when I peeked under the cover so I think the bottom heat I provided definitely helped. I used a thermostat controlled space heater on a low setting, placed on the floor beneath my seed starting rack. This may not be the safest method, but it’s what I have at the moment. My blocks are in used flats that once held 4″ groundcovers, that I begged from a garden center before they disposed of them. I use a trashbag as a cover to hold in the humidity until they germinate (the kitchen size fits two flats). To this point, I have used a spray bottle to water, but I’m thinking a small pump sprayer may be convenient as the plants get larger. I touch the surface of the block to see how dry it feels to decide whether or not to water. I hope to get a similar result as what you describe. Thanks for sharing your experience.

      Mark (via Debbie’s account)

  2. Thanks for all the info on this. I bought a soil blocker last fall and this will be my first year doing it. I imagine it will take a little trial and error but I can’t wait to start using it soon.

    1. Well, Erin, we’re in this together. I’ll be glad to hear about your raging success this year!

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