The Best Soil Blocking Recipe

For years I started all my seeds in plastic seed trays. Even though I like to reuse my seedling trays from year to year, when it came time to purchase a new set of trays, I found myself questioning purchasing even more plastic and I started to do some research where I found soil blocking. Soil blocking has been a game changer for my seed starting system and I’m slowly converting over my entire system to use soil blocking.

If you are reading this article, you’ve likely already discovered soil blocking and are looking for how to make the perfect soil blocking recipe. But can’t you just use seed starting soil? No – in order for your soil blocks to stay together you need to combine materials that have some holding capacity (like peat of coconut coir). The biggest obstacle for many people is finding the ingredients for the perfect seed starting mix to use for soil blocking. Many of the recipes available online are complex and can seem overwhelming.

In this article we’ll explore how to make your own soil blocking mix as well as some resources if you want to experiment with other recipes.

soil blocking recipe
Create soil blocks with this recipe


What is Soil Blocking

Soil blocking is a method of starting seedlings that involves using a special tool to create small blocks of soil. These blocks are then used as individual containers for starting seeds.

Here’s how it typically works:

  1. Making the Soil Blocks: A soil blocker tool is used to compress moistened potting mix into small, cube-shaped blocks. The blocks are usually around 1 to 2 inches in size, depending on the size of the soil blocker.
  2. Planting Seeds: Seeds are then placed directly into the depressions or holes in the soil blocks. One seed is usually planted per block.
  3. Growing Seedlings: The soil blocks with the seeds are placed in trays or containers and are kept in a warm, well-lit area to encourage germination and seedling growth.
  4. Transplanting: Once the seedlings have grown large enough and are ready to be transplanted into larger containers or directly into the garden, the entire soil block, along with the seedling, can be planted. This eliminates the need to disturb the roots by transplanting individual seedlings from traditional seed trays.

See a full article describing how to soil block.

Basic Soil Blocking Recipe

So lets get into the soil blocking recipe. I’ve had great success with the recipe below, but am continuing to experiment with different ingredients. I encourage you to do your own research into the best soil blocking recipe for you.

  • 3 Buckets of Coconut Coir or Peat Moss
  • 1/2 cup Lime
  • 2 buckets perlite
  • 2 buckets fertilizer – I made my own by mixing bloodmeal and colloidal phosphate
  • 1 bucket garden soil
  • 2 buckets of compost

Combine all the ingredients into a large container and use this to create your soil blocks.

soil blocking recipe
soil blocking recipe

Understanding your Soil Blocking Mix

To better understand the soil blocking recipe, it’s helpful to break it down into several parts. All of the ingredients in the list above can fit into one of the specific categories below.

Binding Material: In order for your soil blocks to stay together, you will need something to help bind the soil. Peat moss works incredibly well but is not an environmentally friends options and more people are choosing to use coconut coir as an alternative. I’ve also been experimenting with some of my goats fiber so that may also be an option but I haven’t used it enough to fully recommend it.

Fertilizer/Nutrients: You will need some type of additional nutrients to aid in your plants early growth. I like to use bone meal, green sand, and/or colloidal phosphate. Lime is also useful

Soil: Soil will form the base of your recipe. I’ve seen recipes with both sterilized potting soil as well as garden soil (which isn’t usually recommended for seed starting since it’s not sterile. I’ve had the most success with compost and garden soil combined.

Soil Loosening: You can to ensure that your soil blocks do not become too compacted. Perlite is a great solution and will help air and water infiltrate your soil blocks.

soil blocking recipe
soil blocking recipe

Other Soil Blocking Recipes

Check out this recipe by Hearty Sol

One recipe I plan to experiment with in the future is by the Gardener’s Workshop – you will need to purchase the mineral kits from the website and simply combine this with compost and coconut coir.

How to Soil Block

To review, here is a concise step-by-step guide to soil blocking:

  1. Prepare Soil Mix: Mix potting soil with water until it’s moist but not soggy.
  2. Use Soil Blocker: Press the soil blocker into the moist soil mix to create small blocks.
  3. Plant Seeds: Place one seed in each depression or hole of the soil blocks.
  4. Provide Optimal Conditions: Keep the soil blocks in a warm, well-lit area to encourage germination.
  5. Water Carefully: Water the soil blocks as needed to keep them moist but not waterlogged.
  6. Monitor Growth: Watch for germination and seedling growth, ensuring they have adequate light and water.
  7. Transplant as Needed: Once seedlings are large enough, transplant the entire soil block into a larger container or directly into the garden.

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