Last year we experimented with something called soil blocks. They worked pretty well, so this year we decided to use them exclusively.

A soil block is basically a cube of potting soil that is formed using a mold. Seeds are sown into the top of the cube. Because the blocks have no sides the way a plastic tray does, the seedlings do not get rootbound. The roots grow out and then stop when they reach the air, poised to continue growing outward as soon as the block is transplanted into the ground. The plants suffer less shock when they’re transplanted, and seem to be healthier than those transplanted from plastic trays.

Soil blocks have presented more logistical challenges than plastic trays, however. We haven’t gotten super efficient at making them, so starting seedlings is taking longer than it should. We’re still experimenting with creating a simple, reliable system for marking which blocks contain which plants. And they’re a little more difficult than plastic trays to keep watered properly. The exposed sides of the blocks tend to dry out quickly.

All of our seedlings are started inside in the basement. We have a system of wire shelving, drip irrigation, and fluorescent lighting that provides 150 square feet of growing space. That’s enough space for over 3,000 plants.

The blocks are formed by pressing the mold into a pile of wet potting soil, and then ejecting the compressed blocks onto a tray. The formed blocks look a little like chocolate cake!

Next, the blocks are seeded and marked. They are then transported to the germination bench, where they sit on heated mats under a plastic tent until the seeds sprout.
As we plant more blocks, we’ll add shelves to the germination bench to make more space.

And that’s how we start our veggies!

Cheers.