potting mix for seeds: sand+pumice+peat and no compost?

Jane McGary janemcgary@earthlink.net
Mon, 11 Nov 2019 18:43:49 PST
Yes, I still use about the same mix for seed sowing. However, both the 
sand and the pumice include fines, which is not the case when one buys 
them "washed." I don't think unwashed pumice is available except right 
in the area where it's extracted (here). I would not use coir in a 
compost, but perhaps that's all that is available in some parts of the 
USA. I do use a soluble fertilizer at low strength once the seedlings 
are well developed. I used to use forest humus as an ingredient in bulb 
potting soil, but I moved and no longer have my own forest, so it's hard 
to know what to use. I don't have the equipment to make my own leaf 
compost. I buy something with "municipal compost" (composted yard 
debris) and screen out the bark. I don't like to use any bark product 
when growing bulbs that have a dormant period, because the 
microorganisms that attack the bark also can attack the dead (but 
important) tissue of bulb tunics. For our English correspondents, no, we 
don't have "John Innes mix" in this country.

Jane McGary

On 11/11/2019 5:59 PM, M Gastil-Buhl wrote:
> After much googling for the ideal seed starting mix for bulb seeds, of
> course I arrived at the PBS list, where I should have begun. In November
> 2008 Jane McGary wrote
> "my normal seed mix, which is equal parts sharp sand, screened peat, and
> ground pumice"
>
> Jane do you still use that same mix as 11 years ago? I notice it contains
> no compost and so will have nearly zero nutrients. That seems appropriate
> for long germination times where N-P-K will just grow algae, accumulate
> salts and do no good for the seeds. I assume once seeds are growing that
> you apply fertilizer.
>
>
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