Topic: John Innes Seed Compost v Multipurpose

[plotstoeat]

Just doing some forward planning and getting ready to start sowing in the (cold) greenhouse next month. Toilet rolls in modules, cleaning trays etc and I will have to get some sowing medium. I have always had decent results with multipurpose but can anyone make a case for John Innes Sowing Compost? It should be the very thing but it always seems colder with less air in it. Maybe some vermiculite mixed in would solve that? Your views would be welcome.

[OllieC]

Is that the soil based one? I tried it last year & it seemed very dense & as you say, cold. I used to use a peat based seed one but can't find it any more. Have used MPC before & can't say I noticed the difference with germination or early growth, so plan to use it again next year. Would be interesting to read what others do.

[BarriedaleNick]

For seeds I just use multipurpose compost - mixed down with grit or sand or vermiculite.  New Horizon is the brand I use..

[pumkinlover]

I had got the impression that it was perlite that you mix into the compost and vermiculite went on top,  or does it not matter?
 Bought them both in bulk for the plot shop, much cheaper that way.

[lincsyokel2]

i use JI for seeds, because its loam based and therefore contact with the seed by the medium is better

perlite goes in the mix, vermiculaite on top. No point in doing it the other way, because perlite holds water and vermiculite doesnt.

[plotstoeat]

I know Wikipedia isn't 100% accurate but this is part of the entry for vermiculite:
Seed germination: either used alone or mixed with soil or peat, vermiculite is used to germinate seeds. Very little watering is required. When vermiculite is used alone, seedlings should be fed with a weak fertilizer solution when the first true leaves appear. A tablespoon of soluble fertilizer per one imperial gallon (3.78 : 1) of water is the recommended mix

[lincsyokel2]

I know Wikipedia isn't 100% accurate but this is part of the entry for vermiculite:
Seed germination: either used alone or mixed with soil or peat, vermiculite is used to germinate seeds. Very little watering is required. When vermiculite is used alone, seedlings should be fed with a weak fertilizer solution when the first true leaves appear. A tablespoon of soluble fertilizer per one imperial gallon (3.78 : 1) of water is the recommended mix

The point of perlite is its full of holes, and can hold 40% of its weight in water. The point of vermiculaite is it acts as an insulating layer.  Perlite can also act as an insulator, especially as a fire liner for furnaces and building cavities, and Vermiculite works in any compost mix that doesnt require much water but needs air. if you want a medium that acts as both a top dressed insulator that also holds water, then you use Hydroleca.

But dont take my word, or anyone else's, do your own experiments. My view is coloued because I worked for the man who owned the Perlite factory in Gainsborough.

[BarriedaleNick]

perlite goes in the mix, vermiculaite on top. No point in doing it the other way, because perlite holds water and vermiculite doesnt.

Hmmm not according to anything I can find..

http://www.thegardensuperstore.co.uk/vermiculite__uses_in_the_garden.htm
http://www.dupreminerals.com/downloads/vermiculite/vermiculite-datasheet.pdf
http://en.wikipedia.org/wiki/Vermiculite
http://www.gardenguides.com/79553-use-vermiculite.html

all suggest adding it to compost or soil

The latter specifically states that Perlite does not retain moisture as well as vermiculite

http://worldseedsupply.org/blog/?p=113 - "Both perlite and vermiculite are great at retaining water, but vermiculite retains much more water and offers a little less aeration than perlite"

[lincsyokel2]

perlite goes in the mix, vermiculaite on top. No point in doing it the other way, because perlite holds water and vermiculite doesnt.

Hmmm not according to anything I can find..

http://www.thegardensuperstore.co.uk/vermiculite__uses_in_the_garden.htm
http://www.dupreminerals.com/downloads/vermiculite/vermiculite-datasheet.pdf
http://en.wikipedia.org/wiki/Vermiculite
http://www.gardenguides.com/79553-use-vermiculite.html

all suggest adding it to compost or soil

The latter specifically states that Perlite does not retain moisture as well as vermiculite

http://worldseedsupply.org/blog/?p=113 - "Both perlite and vermiculite are great at retaining water, but vermiculite retains much more water and offers a little less aeration than perlite"

whatever. Do you own experiments, stop believing what you read on the net, trust your own observations.

[BarriedaleNick]

I already do what I think is right - I cartainly don't believe what some people write on the net and sometimes I even reply to them when I think they are wrong.  :D

[plainleaf]

i have always used a peat based seed compost with good results. the important part seeds to be that compost has been sterilized to kill any nasties in it before you use it for seeds.

[goodlife]

Perlite/vermiculate...it all depends what you are making the mix for. But I find vermiculate being generally more acceptable for general seed mixes..its warmer, doesn't hold onto too much moisture and makes airier mixture. I make my own seed mixtures from multipurpose compost (peat based)..but with some more 'perennial' or 'hardier' plants seeds I might add in mix some soil based stuff as well.
I'm not too worried with veg seeds about the 'sterilization'  for nasties..as after all..you can sow seeds straight into soil and its far from being sterilized. But with flowers I always use 'clean' mixes as those often need more 'pampering' to get successful germination.

[bionear2]

We often start with a (peat based) multi-purpose, and mix-in some John Innes, which improves seed contact and slows-down drying out.
Has always worked well for us.

[plotstoeat]

Some really useful replies. Thanks folks. I don't see the point of experimenting when I can benefit from the experience of others. Isn't that what this forum's all about?  :)