Efficiency Of Soil Blocks
When I originally posted about how to use a soil blocker, I had just begun making and starting seeds in soil blocks. I had known about the process for quite some time, but had been a bit skeptical. How could the the quality of plants started from this process make the time and effort of making soil blocks for seed starting worthwhile. Since none of my gardening friends had tried it, I couldn’t just ask someone who was using soil blocks already. I finally let curiosity get the best of me, and after a trial season, I’m hooked.
The Soil Blocker
The soil blocker itself is a simple, although specialized tool. I paid about $30 for the one pictured above, and it seems sturdy enough to last a very long time (I’ve made about 1000 blocks with it so far, with no problems and no signs of wear). Soil blocking mix, the stuff used to make the blocks, is also specialized; but can be purchased for about the same price as potting mix or you can make your own using a proven “recipe.” Either way, the cost is similar to what you would pay for any decent seed starting or potting mix.
The time commitment for making the blocks is a little more than putting soil into seed trays, or about the same as filling individual pots. The benefit here is that you make four pre-watered units at a time with the blocker, whereas potting soil may be very dry at the outset and can take extra time to thoroughly moisten initially. As a point of reference: I usually do 100 blocks at a time, and it takes about a half hour from the time I dump the blocking mix into the bin before adding water, until the blocks are sitting, seeded, under the lights on the growing rack.
Germination rates seem to be comparable to those in other planting mediums: near 100%. Caring for seedlings in soil blocks requires similar effort and time as it does for other seed starting methods. Blocks, however, are best watered either by misting or flooding. One small time saver in soil blocks is that they do not need to be fertilized after germination because the plant food is incorporated into the blocking mix.
To me, the real benefits of starting your transplants in soil blocks are not revealed until planting time. These benefits include:
- Soil block plants have more root mass than comparably sized round pots because of the larger volume of soil contained in a cube versus a cylinder.
- Soil blocks are simply planted in their spot in the garden. There is no pot to remove, no trash, no pinching or untangling of roots.
- Plants started in soil blocks are larger because of more roots and better nutrition compared with those started in round pots and sterile seed starting mix, making them either larger at harvest time or ready to harvest sooner.
- The reduced handling at transplant time allows for minimal transplant shock. Near zero transplant shock results if the seedlings are hardened off before transplanting.
- The particular blocking mix recipe that I use includes a small amount of garden soil. I believe this helps to inoculate the seedlings against some of the harmful fungi and diseases that other seedlings may struggle with after transplant.
- The seedlings I started in soil blocks consistently outperformed store-bought transplants in terms of growth rate and overall health.
The Better Way
After my first season playing with a soil blocker, I believe it to be a superior method for starting transplants. The multiple benefits of using soil blocks were evident from seed to harvest. Taken individually, these benefits may be marginal; but as a package they result in far superior plants from little extra effort and no extra time compared with other seed starting methods.