Municipal composters all have to adhere to very strict ISO requirements
and test regularly. They all hot compost and at the hot compost temps,
pesticides and pathogens break down so they are not a concern. The testing
is their - and you - assurance of that. All that testing is intended to
ensure there are no problems with the municipal composts. I am actually
more concerned about using compost from non regulated facilities like
nurseries.

Nan

Sent from my eye eye phone. All typos are the captain’s fault.

pbs@lists.pacificbulbsociety.net> wrote:

clippings, and I don't use it either for fear of herbicide residue. I do
use a mulch containing compost, but the company that provides it tests the
ingredients for residual harmful chemicals. I like to use a minor
proportion of organic material in bulb potting mix, and most recently I
bought bags of "garden topsoil" from certified organic sources for this
purpose. The main things I avoid are bark, which appears to be attacked by
a fungus with visible mycelia that can also attack the tunics of dormant
bulbs, and perlite and vermiculite, which have no value to the plants and
tend to rise to the top; the latter are also said to be dangerous if you
inhale the dust.

place with an alder woodland on part of it (alders are nitrogen fixers). I
screened the topsoil to make up part of the bulb mix, along with ground
pumice and coarse upriver sand. This worked very well and there seemed to
be no problem with disease, even though the leafmold surely contained all
sorts of microorganisms. I did not use this mix for seed sowing, but
instead used peat as a minor component. I think sterilizing seed soil is
pointless unless you can maintain laboratory conditions, since spores,
etc., will arrive in the air. I used to grow Meconopsis by surface-sowing
on milled sphagnum moss (not peat) as a preventive measure, but since
moving to a place where that genus doesn't grow well, I gave that up.

disease as the tropical and subtropical species some PBS members have.
Surplus bulbs that I've removed to the garden mostly flourish there despite
weekly irrigation in most places. It has always seemed to me that
cultivating these plants as "hard" as they can tolerate results in
healthier populations that appear in character. Coming to bulb growing from
the perspective of alpine and rock gardening is no doubt an influence. My
bulb house is very like an alpine house, but not even minimally frost-free.
Many PBS members might despair at a situation where South African bulbs and
tropical amaryllids can't be grown, but I like the relative freedom of this
kind of gardening.

bacteria and fungi inhabiting half-dead trees would present a problem to
bulbs or if they are sufficiently host-specific that they are harmless in
potting media. For all I know, they might be the same microbes working in
composters.

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