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Germination Frustration with Soil Blocks

Posted by biblion z6 CT (My Page) on
Tue, May 22, 12 at 17:42

For the first time this year I have been trying to use soil blocks to germinate seed. I'm using 2 inch blocks.

I first tried using the starting mix recipe given by Eliot Coleman, a peat/phosphate/greensand/compost mix. I actually did get about a 5% germination rate for head lettuces. Given such poor results, I switched to using a (reduced) peat/compost/potting soil mix (both mixes also contain pearlite). This second recipe, minus the peat, gives me about 100% germination when used in cells or pots. Alas, the seed in the blocks refuses to sprout.

I've tried using lights indoors and growing outdoors, with the same results.

Have any of you had this problem and found a way to solve it?

Follow-Up Postings:

RE: Germination Frustration with Soil Blocks

I've had the same experiences with them and to be honest, have seldom read about much success using them with the exception of Coleman. The soil mix seems to be far too vital an element for me - shouldn't need to be that precise. Plus watering them correctly without way over-watering is difficult IMO. Not to mention the cost of the initial investment in the equipment.

But I will say that IME a good part of your germination issues are because you are using the 2" blocks rather than the smaller ones. It is the equivalent of trying to germinate seeds in 6" pots instead of in 1" cell packs - results are never as good. It is simply too much soil and water volume for good germination and the seed usually rots or even if it germinates the seedling dies off quickly.

How to solve it? Sorry to say tat other than using smaller blocks I never found any solution and finally just gave up on them (as have many others) and went back to more standard methods. 10x better results.


RE: Germination Frustration with Soil Blocks

Thanks, Dave. Wish I'd had the benefit of your experience before I bought the blocking tool.

RE: Germination Frustration with Soil Blocks

Hi biblion. I can understand your issues. Rest assured many are using them successfully, including me. Please check out for some excellent help and live toll-free helpline, too! Soil blocks are fun and easy once you get over the learning curve. Takes a little practice to make nice soil blocks and germinate successfully in them. Soil blockers can be used successfully even to beginner gardeners. Hang in there!

Here is a link that might be useful: Soil Block Makers

RE: Germination Frustration with Soil Blocks

Thanks, greencubes.
I would like to hear more about your experience germinating seed in them.
If by "learning curve" you mean actually making them, honestly? It took about ten seconds for me to figure it out.
I will go check out the website you cite, but its your experience I crave.
I have not given up. Since I originally posted I have had success with Dill, Cilantro and Chard geriminating in the blocks. However, Parsley appears to have an aversion to this medium. Parsley?
I guess what I am trying to figure out is.....
The only thing different about the planting media I've used is peat moss. It doesn't make sense to me, because I've seen Parsley grown in peat pots and it did well.

So, having given a lot more thought to this that it might actually merit, the only explanation I can come up with is that the intitial root system which the plants put down are either A) sensitive to the acidity of the peat or B) unable to penetrate the density of the peat.
From my own experience: its not the density of the peat. I've reduced it to a minimum. though I will experiment with reducing it more to see how little peat might be used to make blocks which hold together.......

RE: Germination Frustration with Soil Blocks

  • Posted by nan-6161 Zone 7 Long Island, (My Page) on
    Sun, Jun 10, 12 at 6:39

I received a soil block maker from a friend for Christmas this year. I used it with promix and had great success with both zinnia and nastursium germination.

RE: Germination Frustration with Soil Blocks

This is my first year with soil blocks. I'm using the 2 inch. I used a seed starting mix (sunshine 360 and second time Promix) combined with compost. 3 to 2 ratio. I had a pretty decent germination rate, I think. I put 3-4 seeds per block, though, so I can't be exact, but I do have lettuce growing in every block and many require thinning. Mine did best without a germination mat and in my basement.

I was coming to the board to ask about soil blocks and the brassicas. Everything else has done very well in the blocks except the brassicas. I sold my extra seedlings, and everyone seems very happy with their plants. I am really pleased with the soil blocks so far.

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