A soil block maker is your key to growing seedlings sustainably, cost-effectively, and most of all, with the BEST root development possible!
Over the years I tried every seed-starting system I encountered, including cheap plastic pots and trays, "plantable" peat pots, cowpots, newspaper pots, empty toilet paper tubes, yogurt cups, egg cartons, milk carton halves, used styrofoam coffee cups, and, for the last decade or so, sturdy, reusable seed-starting flats.
Then along came the soil block maker, which has changed the game entirely.
Here's why I now love starting my seeds using a soil block maker:
Since the soil blocks that come out of a soil block maker have no pot, there are no hard sides that cause a root to start circling around and around in search of freedom. When the roots hit the air at the edge of a soil block, they just stop growing, going somewhat dormant. This is actually much better than circling, because when they get transplanted out they just fire back up, growing down and out in a normal root pattern that will continue to develop fully (this is a case where "down and out" is a good thing!).
The deeper and wider roots can grow, the more nutrition and water they can gather and the more resistant to drought and disease they will be. This is explained in much greater detail here.
It's important when starting seeds in soil blocks to get the timing right, or you'll end up having to "pot-up" your soil block into a larger block or pot, which somewhat defeats the purpose of not using plastic. You can visit the When to Start Seeds Indoors page for help on getting the timing exactly right for your region and your specific crop, so your soil block seedlings can go straight in the ground at the right time.