Soil Blocks

[Sandbar]

Has anyone use soil blocks to start transplants? I find this idea interesting and wondered what successes (and failures?) folks had experienced with them. I like the idea of starting my plugs with soil blocks instead of buying plastic every year.

TIA for your input!

[Angela Adams]

i've tried this recently, with tomato seed. i used the 3/4-inch size to start with, using a coir-based seedling mix; i set the blocks in an old 3-sided drawer (similar to that recommended by eliot coleman in his organic grower book). after i ejected them from the mold, i spaced each row of blocks a little because i planted a different type of seed in each row and didn't want to confuse the seed types. then i covered the drawer w/plastic to keep the environment humid. i didn't line the bottom of the drawer w/anything like newspaper which would wick away the water from the soil blocks. i have a metal-halide grow light suspended above the drawer providing light.

okay, i did something wrong because: (1) the blocks dried out, and kept drying out (probably separating the rows was the problem here), no matter how often i misted them; and (2) the blocks grew some nice, hairy mold - environment too humid perhaps, or not enough fresh air. seeds never did sprout. :confused:

so, i scrapped the 3/4 inch blocks and went to the 2-inch blocks. didn't separate the rows, put them in a plastic tray w/a transparent plastic lid, and set them under the same light. seeds sprouted in 3 days. no hairy mold. :p

i recommend starting w/the 2-inch blocks.

[austransplant]

This year I started seedlings using 2inch soil blocks. My recipe for making the blocks was a mix of coconut coir, county leafmold compost (Leafgro -- good compost made by Montgomery county in MD), and some sand. Blocks made from this mix hold together well, though making them is a bit messy.

I started seedlings in these under fluorescent lights. The blocks do dry out quickly, especially those at the outer edges of trays. I spray the blocks with water each day and poured a little water around the bottom, which the blocks quickly soaked up. But in general it seems you need to be more careful with water with these blocks than with seedlings started in containers.

Besides the drying out issue, the chief negative aspect of the blocks is that the plants roots will grow out under the block where the block rests on a tray, though not at the sides if space is left around them. Eliot Coleman claims that one great advantage of blocks is that the plant is forced to develop a strong root system throughout the block, since the roots cannot circle around as they do within a pot. This is true, except for the root at the bottom. This might create problems for plants with strong tap roots.

I had excellent germination in these blocks. Tomatoes in about 5-6 days, parsley in 10 days and so on. And plants grew well in them. The county compost did contain some fungi, and little toadstools tended to grow on the side of the blocks, but this seems to have created no problem for the seedlings (maybe it is even a benefit -- who knows?). I had no damping off problems.

I have since transplanted parlsey into the garden, and it started growing well.

All in all, the blocks seemed to have worked quite well.

[LoreD]

I had great success with the soil blocks. I do agree that they dry out under the lamps. I found that the best way was to use the plastic seedling flats and leave enough room between each group of 20, 3/4 in. group of blocks, I then watered them from the sides and the water flowed around the blocks and they absorbed the water from the bottom. I found that if I misted them that they never absorbed the water unless I sprayed for about fifteen minutes and I have arthritis in my hands so that definitely was not a possibility.

Worked great for me.

LoreD