If you’ve been thinking about trying soil blocking, you might have found that there are an overwhelming amount of soil-blocking recipes online. But which one is the best option for seed starting? I’ve experimented with several different recipes, so you don’t have to!
In this post, I’ll break down the pros and cons of soil blocking, the best recipe to ensure your soil blocks don’t fall apart, and my tips and tricks to get the most out of your soil blocking experience! Let’s get into it.

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WHAT IS SOIL BLOCKING?
Soil blocking is essentially the manual process of making soil blocks. This is done by packing a handheld tool called a soil blocker with a soil mixture (more on this below) and manually pressing that mixture into blocks. You can then plant your seeds in these blocks, place a tray of them under a grow light, and begin the germination process! With the proper technique, soil blocking can be a fun, easy way to seed start, which eliminates the need for various seed-starting pots and sowing trays.
Related: Indoor Seed Starting Schedule for Easy Vegetables & Flowers
PROS & CONS OF SOIL BLOCKING
PROS
- healthier root systems are produced through air pruning and an increase in oxygen
- no transplant shock–some plants don’t like to be bumped up in their seed containers or moved once they’re started. if you soil block, your roots stay in the same container, and it’s easier for the plant to climatize to life outdoors
- the ability to start more seeds indoors
- ease of transplant into the garden
- reduced use of plastic containers
- the ability to save money in the long run
CONS
- the initial cost of the soil-blocking equipment
- not ideal for larger vegetables like pumpkins or squash
- can be a little more time-consuming than other methods
- a sharper learning curve initially than traditional seed starting
Related: DIY Seed Starting from Your Window
WHAT SUPPLIES DO YOU NEED TO SOIL BLOCK?
These are the basic supplies to get started on your soil-blocking journey:
- soil blocker
- potting soil, seed starting mix, or a combination of peat moss / coconut coir, perlite, all-purpose fertilizer, topsoil, and organic compost
- spray bottle
- seeds
- seed tray
Related: How to Start an Indoor Herb Garden from Seeds
WHAT IS THE BEST SOIL-BLOCKING RECIPE?
I recently experimented with various soil-blocking recipes to determine which soil-block recipe would work best for my gardening needs. I tried plain potting soil, plain seed starting mix, the classic Eliot Coleman recipe, and a version of the Eliot Coleman recipe with coconut coir, a more sustainable alternative to peat moss.
While there was no clear winner, as you’ll see in this video, I did find that the best results came from ingredients that were as finely milled as possible. That said, if you don’t have much time, I suggest using a seed starting mix. If you’ve got the time, the coconut coir mix stands out as the one I will use again. I would stand by any of these mixtures, though, as long as you use the correct watering technique and tightly pack the cubes.
Both of the recipes below produce about 2 bushels of soil block mix. The term “bucket” refers to a 5 gallon bucket. If you use a smaller bucket or container for your base measurement, make sure to scale back on your use of fertilizer in proportion.
The Industry Standard: Eliot Coleman’s Recipe
- 3 buckets finely milled peat
- ½ cup lime (use agricultural lime if you can get it)
- Add 2 buckets coarse sand or perlite and
- 3 cups fertilizer (use an all-purpose one where the NKP numbers are all the same)
- 1 bucket garden soil or bagged topsoil
- 2 buckets screened compost
Mix all ingredients thoroughly
Coconut Coir Seed Blocking Recipe
- 3 buckets coconut coir
- 2 buckets perlite
- 3 buckets finely sifted compost
- 1/2 bucket worm casings
- Optional: 3 cups fertilizer (use an all-purpose one where all three NKP numbers are the same)
Mix all ingredients thoroughly
2025 Update: The recipe below is good for home gardeners who only need one or two trays of soil blocks. This recipe would work well for one standard sized tray of large soil blocks and one standard sized tray of tiny soil blocks. I used a 2-litre milk jug as my measuring cup.
Wool Pellet Seed Blocking Recipe
- 4 litres seed starting soil
- 4 litres coconut coir
- 0.5 litres worm casings
- 0.5 litres wool pellets
- 1/4 cup fertilizer (use an all-purpose one where all three NKP numbers are the same)
Mix all ingredients thoroughly
Tips for Beginner Soil Blockers
1. Allow coconut coir and wool pellets enough time to soak through
As I’m trying soil blocking again in 2025, I realized when I was using the wool pellets is that I should have maybe let them soak in my soil for about an hour or two, because the next morning when I looked at my soil blocks they were all puffy. I think this affects the mix a little bit, but we’ll see as the plants grow a bit if they pull apart a little more. I don’t actually know at this point!
After I shared on social media my process for using coconut coir, which felt a bit ridiculous, followers let me know that you’re actually supposed to soak it in a large tub of water and let it soak for 2-3 hours. It’s best not to take the coconut coir apart until it’s completely soaked through.
So, if you’re wanting to seed start promptly with your soil blocks, there is some advance planning that needs to happen with both the wool pellets and the coconut coir. You can’t just decide on a whim that you’re going to do this, and it will all work out well.
2. Pack your soil blocker well so your blocks don’t fall apart
It’s worth it to take the extra time and make sure you’ve really got the soil in the soil blocker good, as the blocks can fall apart when you water them if they weren’t initially packed tightly enough. If your soil block looks like a brownie, you’ve done it correctly!
3. Keep your soil blocks moist
The best method for keeping ¾-inch soil blocks moist is to use a spray bottle. Misting soil blocks with water helps hold them together and prevent them from drying up and crumbling.
When you’re bottom watering, leave a space in your soil blocks to pour the water, so it doesn’t immediately hit the soil. If you pour the water this way, they shouldn’t fall apart. Be warned: if you pour the water directly into the center of the blocks, they will break apart.
If you liked this blog post, find me on Facebook, TikTok, and Instagram for more cold-climate vegetable gardening tips, delicious recipes, and cut flower goodness! I also make weekly videos over on my YouTube channel. I hope to see you there!
HAVE YOU TRIED SEED STARTING, ONLY TO BE LEFT WITH STRETCHED-OUT SEEDLINGS AND DEAD PLANTS?
You’re not a bad gardener–you just need a little know-how. For the price of a few seed packets, you can stop wasting time and money and start growing seedlings that actually live, and you get to harvest. Don’t miss out on another growing season. Get your copy of Seed Starting Success now (videos included)!
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Kathy Quinn
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