Is My Seed Raising Mix Really Bad?

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Is My Seed Raising Mix Really Bad?

Postby abrogard » Fri Jan 06, 2012 3:49 pm

Here's a couple of pics of my homemade seed raising mix. It seems to develop a hard crust on it and it seems to be growing that green mold you get in stagnant ponds and such.

In these pics it's chives making their way up here and there:
IMG_9519 [640x480].JPG
How The Tray Appears Generally

IMG_9521 [640x480].JPG
Close Up Showing Crust and Mold

Is this really nothing at all to worry about? Or is it very big no-no I should fix immediately.

The mix is 50% compost ( a council 'tip' compost ), 25% sand - a builder\s sand from off the job and definitely kinda fine, and 25% my garden soil - also very fine sand, really.

It doesn't look right to me. In fact it looks horrible...

My thoughts are that the compost I'm using is too 'tarry' or something, not like other composts... and that my sand is too fine and needs replacing with something.

Perhaps adding some of the coir I got yesterday might help? I guess it needs grating up first though?
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Re: Is My Seed Raising Mix Really Bad?

Postby lucylu » Sun Jan 08, 2012 4:33 pm

You put builder's sand in it? As in yellow sand? I don't really understand why you would add this in if you have sand available in your garden? I'd leave it out.

I thought the seed raising mix you buy is sterilised? But I don't know.

I'd say the compost is not having a good affect on your mix.

I've made my own using God's gift to gardeners compost (very well composted and very fine) mixed with cocopeat and sand. I soaked the cocopeat in seasol.
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Re: Is My Seed Raising Mix Really Bad?

Postby goldbullion » Sat Jan 21, 2012 11:17 pm

A good seed raising mix needs to allow oxygen in and for water to drain freely.
For seeds to germinate they don't need any fertiliser or nutrients.
I would sift the compost to allow air into the mixture. If the mix is crusting the seeds will struggle to germinate properly. I would also avoid builders sand; it's not washed so may contain salt and other elements that may inhibit germination or cause problems for your seedlings.
Garden soil is also problematic as it tends to be too compacted to make a good mix. In addition you may find many weed
seeds germinating too.
Coco peat is a good medium together with washed sand and/or perlite/vermiculite.
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Re: Is My Seed Raising Mix Really Bad?

Postby abrogard » Sun Jan 22, 2012 7:50 am

Thanks for these replies. I'm still struggling to get a handle on this and to get a good seed raising mix.

I would rather not buy one - I'd like to have the understanding and the ability to make as required.

Constantly I'm thinking I need something a little more than a 'sterile' mix that allows seeds to germinate. I would like a nutritional environment for them to start life in if possible. A little more nutritious than those mixes that require constant fertilisation from scratch. So that's why I look for some 'heavier' ingredients, such as garden soil.

Plus I see the germinated seeds as spending some time in those trays before being planted out - reaching some size, maybe 100mm (as is frequently suggested on seed packets - I still read them, I'm still this raw beginner in his first ever season of growing ). So I'm seeing the seed raising mix I will use, I need to use, as being a half way house between those open, sterile, vermiculite looking mixes and a potting mix.

And there's a thing: some of, many of, those potting mixes appear to be open, sterile, vermiculite mixes, too, but that's another thread, I guess.

I put the builder's sand in because I was copying a recipe which didn't (I suppose) take into account that my soil might be so sandy. ... ising.html

But in any case that thought crossed my mind and went: my soil isn't sand, it's silt, the 'builder's sand' apparently has the ability to 'open' compacted soil and allow water through, hence: add the sand as instructed.

Probably I was in error. The builder's sand I used is anything but coarse grained and I guess coarse grained is what is needed for the sand to be able to 'open' the soil. And then again the soils it would 'open' would be clay soils I guess and mine is at the opposite end of the spectrum from clay.

So what shall I do now?

Think of my soil as 'sand' ? No. Because it doesn't have the coarse sand properties.

Forget my soil? Make a mix with 100% imported ingredients?

I got some coir. Soaked some in a bucket and took a look. I can see how useful it might be, especially in a soil or potting mix. But I guess I got the wrong one. Mine has great big chunks in it, 15mm cubes or bigger.

So get fine coir?

Get coarse sand? Or use only one of these two?

Get compost. Any compost? The one i've been using after wetting slumps down into a sort of tarry layer when used as a mulch and it looks like it is doing the same thing when mixed into a seed raising mix - it is making a crust. It doesn't mix in well. So find another compost?

Here's a compost/coir/sand/perlite recipe:

Here's one I like with sand/cowpat and in sandy soil areas she says just use soil - excellent for me
and for potting on, which she does at 5cm, she simply adds compost to the mix.

I like the sound of that last one so much I'll try to go with it. If I take the finer bits of the coco peat I got and mix it with my soil (thinking of it as sand as that last URL suggests) then I've got a mix.

And that's just about the mix goldbullion suggested, too.

Soil and cocopeat. Couldn't be easier. I've been making it too heavy, with extra fine sand and compost. Just leave 'em out.....

Back to the shed....
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