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In this post Julie and Kevin demonstrate how to start seeds using soil blocks and explain why they went potless.

Watch the video, How to Start Seeds with Soil Blocks, on YouTube.

Starting seeds indoors is a great way to get an early start on vegetable gardening, especially in climates like ours where the growing season is cooler and shorter than many regions. It can also be more affordable than buying starts or seedlings from a nursery. Another benefit of starting your own seeds is that a much wider variety of plants is available, making it easier to find varieties suited to your bioregion or gardening zone. Be sure to check out our Top 5 Seed Suppliers post if you are looking for trusted sources.

Containers for Starting Seeds

There are so many ways you can start seed indoors! We’ve heard of people using everything from eggshells to those disposable metal lasagna trays you can buy at the grocery store. There are two types of containers most commonly used to start seeds. They are widely available at nurseries, hardware stores, and online. The first is plastic containers, which are often called cells or trays. The second is decomposable containers, which are also sold under the name peat pot or cow pot.

Over the years we have used both plastic cells and peat pots. Each of them has pros and cons. Overall though we noticed common issues with both of these kinds of containers, such as seedlings getting root-bound. Getting these plants into the ground sometimes damaged the roots, or caused the plants not to spread their roots. These problems can lead to plants being less vigorous, making them more vulnerable to pests and diseases as well as not producing as much food.

Making the Move to Soil Blocks

After running into issues starting seeds with both plastic and compostable containers, we began researching alternatives. Early on, we looked to Eliot Coleman, of Four Season Farm in Maine. He’s an author and gardener we have admired for decades. He’s also the one who inspired us to grow vegetables during the winter.

Through Coleman’s articles, we learned about the soil block method. He prefers this method because the roots of the seedlings do not circle inside the pot (the issue we had been having) but instead “air prune” by growing to the edge of the soil block. This made us excited because it was not only a way to reduce our use of plastic, but could create healthier seedlings!

Soil Blockers

To create soil blocks, you need soil blocker tools. We have learned the hard way that it’s worth investing in good tools. So while there are several companies that make soil blockers, we use only those made in England by Ladbrooke. You can tell if you have a genuine Ladbrooke because they imprint their name patent number right into the handle. At this time we have 3/4” blocker and a 2” blocker. Someday we hope to also own the largest version, which is the 4'“ blocker. The blocks are designed to fit into each other, so as plants grow, you can “pot up” or put the smaller blocks into the bigger sizes.

How to Make Soil Blocks

As Kevin says, if you could make mud pies as a kid, you can make soil blocks. But there is a bit of trick to getting good blocks. First is having a good soil mix and consistency. We use our raised bed soil mix combined with worm castings from our worm bin. Then we run the soil through a sifter. Then we add a lot of water to this mix. A lot of water. Think cake mix consistency.

At this point we press the tool into muddy mix and keep pressing it into the soil until water starts to seep out the top. Then we turn the tool over to make sure all the squares are full. Using a hand trowel, we scrape off excess soil. Then we position the filled soil blocker over our seedling tray and using a ‘double squeeze’ method we push the blocks out.

We set up our trays with big and small squares so that one tray can function for a group of seedlings as they grow. This helps us manage our starting space (of which there is never enough).

Sowing Seeds in Soil Blocks

Once the tray of soil blocks is complete, we sow our seeds. Using a toothpick or skewer we poke a hole in each of the 3/4” blocks. Then we drop one seed into each block near the correct depth (which is usually printed on the seed packet). Once all the blocks are seeded, we go back and seal the block back up.

We try to make sure that each tray has seeds with similar needs. For example, cool season lettuce and kale go in one tray, while heat-loving seeds like eggplant and chillis go in another.

Don’t Let Perfection Paralyze You

Whatever method you decide to use for starting seeds, don’t worry about getting it perfect! The best container for you is the one you’ve got. Reading and research is important, but the learning that you will gain by doing can’t be beat. Each growing season brings new learning and new ideas.

Keeping notes about your own garden will help you build on your experience year after year. If you don’t have a garden field journal and you aren’t sure where to start, be sure to check out our FREE Quick Start Vegetable Gardening guide, which has some nice blank template pages in the back. We created these based on our garden journal.