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