I have been using toilet paper rolls for my first stage nursery for years. Last year I moved, and since I had no idea where I would land I recycled them.
Now I have only a few, nowhere near enough for spring planting.
After a great deal of thought, I have purchased a silicon ice mold and will be using it to make soil blocks. I will be using the native soil (heavy clay loam) and would like to hear from people who have used soil blocks in the past.
Advice? Drawbacks?
I’ve used soil blocks, but I used a mixture of peat, perlite, and compost, with some native soil (clay) added to help them hold together. My guess is that clay soil by itself would compact too much to work for seed starting blocks.
With the peat-based mix, the blocks worked really well for me.
Thanks. The goal here is to find something I can do with no external resources, which puts peat and perlite off the list.
I use soil blocks, and try to not buy anything. It was hard to get away from at least a little coco though (but sometimes that was just a lack-of-time problem). The thing that made it work for me if I had the time, was sifted oak leaf mold. I had access to a tan oak forest where I would get bins of rotting leaves +soil. Then sift that and make it a heavy part of the mix. Instead of perlite I used composted biochar for more aeration. That worked, but again I was lucky with that. I did some blocks of tomatoes with pure soil, they were really stunted because of lack of oxygen in the root zones. So I think you’ll do fine if you can just find some source of aeration for your clay.
Here’s a random video. Sand is in the recipe here, from Elliot Colemans recipe, but I stopped needing it.
Last week I was on a tour of the Chinampas near Mexico City. This farm makes soil blocks from canal silt. Dries for a day on wood, then cut into blocks, then press a hole in the middle of the block.
They have two depressions about 4’ x 20 '‘- the first one for the seeds just started that need extra warmth. 2nd is for holding the starts ready to be planted.
Having it in the soil instead of in trays keeps them moist longer. Hoops with greenhouse plastic for protection.
This one had the plastic removed for hardening off. We took from this open section to plant some flower blocks.
When I asked for advice on alternatives to canal silt, they suggested mixing your own soil with purchased potting soil. So I’ll probably stick with my previous recipe of native soil, worm compost and leaf mold. It was nice to see soil blocks working well with what looked like compressed native soil, nothing added.
Here is their demonstration farm in Xochimilco. In the summer there are milpas everywhere, during winter most of the plots grow greens for the market. The canal water all comes from a water treatment plant, its high PH and you can see effects of high minerals.
