America’s Test Farm: Let’s Try Soil Blockers

At Area 2 Farms, we're always experimenting to find better, more sustainable ways to grow. This time, we tested an alternative to our usual seed-starting trays: soil blockers. These tools compress soil into cube-shaped blocks. But do they actually work better? We put them to the test in a side-by-side trial with our standard method. Here's what we learned.

What is Soil Blocking?

Soil blocking is a novel seed starting method that molds soil into compressed cubes, no trays needed. We wanted to see if this technique would improve seedling health by increasing airflow to roots, reducing transplant shock, and eliminating the cost and need for storage of plastic trays for both our farm and homegrowers alike.

Soil Blockers vs. Standard Trays

At Area 2 Farms (like most farms) our go-to method for seed starting uses 1020 or 200-cell trays. We start everything from basil to lettuce greens to rosemary cuttings and petite red-veined sorrel in these trays. 

To test the soil blockers as a potential alternative, we designed a side-by-side comparison. We looked at how long each method took, how easy each one was to use, and how the plants performed.

Preparing the Soil

To start the comparison, we prepared the soil using our standard Area 2 Farms Composted Potting Mix, which includes:

• Coco coir

• Peat

• Compost

• Perlite

• Beneficial microorganisms  

Following the cube maker's guidelines, we moistened the mix until it reached a paste-like consistency that held its shape when formed into a ball. Here’s where the time difference stood out: filling a 200-cell tray took just about 1 minute, while preparing 200 soil cubes took about 5 minutes.

Testing the Methods

We tested two methods to see which worked best for seed starting:

• 20 soil cubes made with a microgreen compost and water mix

• 20 transplants in our standard 200-cell trays (our control group)

The soil cubes were tricky at first: hard to keep intact and didn’t form clear holes for seeding. Seeds sat exposed on the surface, and when we tried to push them in, the cubes began to crumble.

Despite that, both methods had nearly 100% germination within four days.

Each method had its trade-offs:

• With the 200-cell trays, roots occasionally broke away from stems during transplanting. The soil cubes, on the other hand, held together well and were easier to move into growing containers.

• Cleanup is also simpler with soil cubes. Washing 200-cell trays takes time—removing old soil, soaking, scrubbing each cell. With soil cubes, it’s a quick rinse and a wipe-down of the flat tray.

• And when it comes to storage, the 200-cell trays take up much more space. The compact soil cube setup is not only easier to store, but more versatile, too.

Yield Results & Final Takeaways

Once we transplanted the seedlings to our garden beds, the differences became clear. The 200-cell transplants yielded 359.0 g/m2/week, while the soil cubes produced 323.7 g/m2/week. That’s a 9.8% increase in yield from the trays. The trays held more soil, which gave our lettuce a head start. Plants were heavier and looked healthier overall.

Soil blocking is a promising idea, especially for reducing plastic use and appealing to eco-conscious growers. But the practical challenges—fragile cubes, tricky seeding, and slower growth—make the standard 1020 trays the more reliable method for us. We’ll keep experimenting, but for now, the trays are the more reliable option for Area 2 Farms.

Area 2 Farms for Locals

Your food should be equally accessible and nutritious. Which is where we come in. We’re Area 2 Farms, we grow organic produce, deliver it to your door weekly, and operate all within 10 miles of you.