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Potting on in soil blocks

Posted by macky77 2b (My Page) on
Sat, Mar 10, 12 at 18:43

Over the winter I bought a set of soil blockers. I've started a few shallot seeds in the mini blocks and they're now ready to go into the two-inch blocks. I attached the square inserts and went about making the blocks. When I inserted the mini block, though, it was smaller than the hole; there's no soil contact between the two cubes except on the bottom of the mini cube. That doesn't seem right. Any idea what I may have done wrong?

My other issue is that sometimes the roots are not penetrating the mini blocks. The seed germinates and then the root grows sideways instead of down. I tried moving them under the lights to see if that would help them orient themselves, but it continued to happen here and there as the rest of the seeds germinated over the next couple of days. I'm going to try setting the mini blocks on a wicking mat next time in case the trouble is that I'm just not keeping them wet enough and the root can't penetrate the compressed medium. (I'm already misting them three or four times a day. I draw the line at setting an alarm to mist them in the middle of the night, too; not gonna happen.) Do you think that might be the issue or is there something else I might be missing?

Follow-Up Postings:

RE: Potting on in soil blocks

I gave up on soil blocks a few years back in part, for the reasons you mentioned. You can 'adjust' the size of the insert hole a bit by using less pressure but what I did was set the mini cube in the hole and then sprinkle a bit more mix on top and lightly press into place. Kind of makes for messier blocks but works.

The side rooting problem is due to the compression of the mix you are using. When I made it a bit looser the problem went away. But if not it doesn't really hurt anything as they grow fine.

Hope this helps.


RE: Potting on in soil blocks

It does... thank you, Dave! I had to make substitutions because I couldn't find everything on the list and that may be contributing to the mini blocks being too compressed.

I still like the idea of starting seeds in the blocks, once I get the mix right, of course. I hate washing pots and cell packs with a passion. I think I might abandon the notion of potting blocks on to each other, though.

Tried setting a few on some dense fleece last night to see if it would wick from a bowl of water. It didn't. I guess I need the proper wicking mat. Not going to the city for a few days yet, though, so will have to keep misting until I can get to Lee Valley.

RE: Potting on in soil blocks

Plain old felt - the kind they sell in craft and sewing sections - will wick. Cotton terry - like towels - will to. So will the plain cotton clothesline.


RE: Potting on in soil blocks

Just wanted to update this thread now that spring is here.

I gave up on the mini blocks for the aforementioned reasons (for this year anyway), but did decide to go on and start the majority of my pole beans in the 2" blocks using just some Pro Mix BX. The blocks seems too spongy when I was making them, but they worked beautifully! The blocks did hold together very well in the end.

I transplanted some of them yesterday and the beans I started in the blocks were noticably stockier and much easier to handle than those I started in the cell packs, where the soil was looser and the plants quite a bit leggier. There was no overcompression with this soil mix, even though I didn't change my packing technique from the last (failed) attempt. I wonder if it was the better quality of peat in the Pro Mix BX compared to the cheaper peat I was using in my own homemade mix. The roots had no trouble pushing through this time.

I bought a fogging nozzle and found it a lot easier to water them that way, too. :)

RE: Potting on in soil blocks

Nice discussion.

For wicking I found an dead pine branch ~4" in diameter and cut it into 2" slices. Each slice then holds a 3" diameter soil block which I make right on top of the slice. I use ABS 3" pipe to mold them and a metal water bottle as the plunger. A normal black seedling tray holds 8 of these blocks with a pine slice base.

Watering is easy just water to the bottom of the tray about 1.5" and the pine slice wicks up plenty of water to the block. The soil doesn't get disturbed at all and no misting required.

It is also easy to move individual blocks around before plants have sprouted, since they have a hard base (pine slice) to hold them from.

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