We're heading into the last couple weeks of April and I feel experienced enough with soil blocking to write a little bit about it. First off.......I love soil blocking! I really, really do. I just discovered the soil blocking method this past year, but then I began to wonder, where did soil blocking come from? Mexico! Yep, about 2000 years ago an Aztec tribe retreated to the "Floating Gardens" area, which is present day Mexico City, and they devised the Chinampas method of gardening of which the seedling nursery technique (or soil blocking) was integral. The soil blocks, or chapines, were made from muck which had been dredged from the drainage canals in the Floating Gardens area and dried on piles of weeds. The chinampero (farmer) would then make a small indentation with his little finger or a stick in the top of the chapines and then drop in a seed and cover the seeds with loose manure. The chapines were watered until the seedlings were of a size to be planted into the chinampa.
I wanted to try soil blocking this year for several reasons, but the main reason was so I would not have to buy all shapes and sizes of seed trays and then wash them and store them from year to year. With the soil blocking method I only need one size seed tray, the standard 1020 seedling flat without drain holes. These will be easy to quickly clean out after transplanting and will all stack together in a small pile. Use of the clear domes is optional. Clear plastic wrap works very well in place of the domes during germination.
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| Standard 1020 tray without drain holes |
My other reasons for wanting to try soil blocking included the fact that I wanted to mix my own soil anyway (versus utilizing a prepackaged mixed soil), I liked the idea of the roots of the seedlings being air pruned instead of encircling the seed trays, and I liked the idea of the ease of transplanting the soil blocks into the garden.
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| Tray of 50 2-inch soil blocks |
There would be one reason that I can think of now why I would use plastic pots or divided seed trays in the future for starting seeds---if I decide to sell plants commercially. Most customers would probably prefer to buy a tomato plant or petunia in a plastic container instead of just getting bare blocks of soil containing the plants. However, I may be able to convince them otherwise if I ever get to that point.
What I've discovered thus far in my soil blocking experience is that they are very simple to make if you just follow the basic directions. There are videos on YouTube that show you step by step how to make the blocks. There are many "recipes" for making your own soil mixture on the internet. I use the recipe that Eliot Coleman uses in
The New Organic Grower with just a slight change. Once you make one batch of soil and experiment with the soil blocker, you pretty much have it figured out. If you buy your basic ingredients in bulk, the cost per tray is minimal. Once I purchased my initial ingredients, I was set for thousands of soil blocks. A bonus that I had not anticipated with making soil blocks......kids love to make the blocks! I had a group of middle schoolers come out to the gardens last week and several of the boys had a blast making trays of blocks.
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| One 12-inch tomato plant in soil block |
At this date I have tomato plants in the greenhouse ranging from tiny seedlings to 12-inch plants. They are all in 2-inch blocks and they are all doing great. Because of the organic nutrients in the soil mix, I have not needed to fertilize anything and I do not anticipate needing to do so before they are transplanted out into the garden. Even the largest tomato plant roots are air pruning in the blocks which means when the roots grow to the edge of the soil block, they automatically hold back when they sense air. As you know, if a 12-inch tomato is in a plastic pot the roots will not only be circling the inside of the pot, but also growing out the drain hole in the bottom. The worst case scenario with soil blocked plants is if you have the blocks very close together, roots may eventually grow from one block to another, but it is easy to take a knife and quickly cut between the blocks when you're ready to transplant and the plants will be fine.
I am looking forward to being able to start transplanting some of the hardier plants out into the garden next week such as seed onions, brussels sprouts, and cabbage. I anticipate it will be an easy transition for the plants as they will be moved with their own dense package of soil and placed into the garden where they will quickly spread their roots and thrive.
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| Micro and 2" soil block makers |
One more positive note about soil blocking, watering the seedlings is much simpler than with traditional seed trays or plastic pots. Those little plastic cells and pots will only take so much water, then the rest drains out and the seedlings dry out very quickly when they have a lot of root mass, especially on very warm days. Even on the hottest days (and sometimes my greenhouse gets well over 100 degrees) I just fill the flat tray full of blocks with water so that all of the blocks are sitting shoulder deep in water. They will immediately absorb some water, but what they don't absorb can be left in the tray for absorption later in the day with no chance of the blocks disintegrating or the seedlings rotting. I've tested this many, many times with the unseasonal heat we had late winter/early spring and the seedlings all did great!
Michelle@BearButteGardens.com
www.BearButteGardens.com
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