sustainable potting media
Jane McGary via pbs (Sun, 17 Dec 2023 11:21:13 PST)

As Mark mentioned, municipal compost in this area includes lawn
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.

When I started growing bulbs seriously around 1990, I had a country
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.

Probably the hardy, summer-dormant bulbs I grow are not as vulnerable to
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.

Jane McGary, Portland, Oregon, USA

On 12/17/2023 8:18 AM, Robert Lauf via pbs wrote:

_______________________________________________
pbs mailing list
pbs@lists.pacificbulbsociety.net
https://lists.pacificbulbsociety.net/cgi-bin/…
Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net>
PBS Forum https://…