sustainable potting media

sustainable potting media
mark akimoff via pbs (Mon, 18 Dec 2023 09:11:19 PST)

HI Tim,

Get 6 pots that you will be using to germinate your seeds in, you can use
beans, tomatoes, cucumbers or mustard greens, pretty much any fast growing
annual vegetable seeds will show some sort of toxicity response, I think
cucumbers are used because they salt tolerant and highly sensitive to most
common pesticides especially growth regulators like 2,4d that show up in
municipal composts because of lawn clippings. Plant 8 seeds per pot, but
make sure 2 of the pots are known to be pesticide free, like something from
your garden where you know hasn't been sprayed (control group) or a bagged
commercial mix that you trust.

Put the pots in warm, well lit place just like you are starting seeds and
record the results when they start germinating. Stem twisting, stunting,
yellowing, deformities of the growing tips or failure to germinate can all
be signs of toxicity of some sort. Hopefully all the pots germinate and
grow away with strong and healthy seedlings and you know you should be good
to go to use it for your valuable seeds. Share your results with us!

Some time ago, I had a commercial lab do a soil test on my three way soil
blend that I use for growing bulbs commercially. It's a three way of
Composted Cow Manure, Screened sandy loam topsoil and pumice. I do
occasionally see some salt burn on the tips of emerging bulbs, some South
African species like Ferraria seem particularly susceptible to it. I know
it's salt because the soil test showed high levels likely from too fresh of
cow manure, In this case, and possibly with your mixes you have made, you
can leach out some of the problem by leaving the soil exposed to rainfall
for a season.

Mark

On Mon, Dec 18, 2023 at 8:04 AM Eric via pbs <
pbs@lists.pacificbulbsociety.net> wrote:

All these horror stories of losing plants to bad compost has me worried. I
used a local company from which I’ve purchased mulch, topsoil and sand.
I mixed up some potting mix to plant an entire season of seedlings in
larger pots. Now, I hope I didn’t kill the lot.
I have some of the compost sifted and sitting in 55 gal cans.
Can anyone detail the “cucumber test” mentioned in earlier post.
Thanks
Eric

Sent from my iPhone

On Dec 18, 2023, at 10:26 AM, Joseph Gorman via pbs <

pbs@lists.pacificbulbsociety.net> wrote:

Tim,

I've had mixed experiences with municipal compost. When I lived near DC,
there was free "leaf mulch" they shredded in small batches and left at
transfer stations. It didn't get hot but never gave me any trouble with
trash, herbicides, weed seeds or pesticides.

I tried municipal compost from a few smaller cities within about an hour
from me before I found any that seemed decent. Lots of rocks and plastic;
some of the composts I saw didn't resemble composted organic matter at

all

and seemed more like dredged river sediment. Used one city's compost that
had industrial windrow machines and temperature logs and was happy with

for a few years before I got a batch in 2018/2019/2020 that contained

high

levels of an (aminopyralid?) herbicide, killing off thousands of square
feet of garden that still not even weeds will grow in. Some of the tree
service folks around here run their own composting operations, and I'd
trust their stuff a little more with regard to herbicides but less with
regard to temperature control.

I don't currently mix most of my own potting mixes, but when I do I buy a
lot of the raw ingredients from a local potting soil mixer (Dirtcraft
Organics) or get custom mixes if I can get in on a group buy. Their

compost

comes from hospital food waste in Charlotte, the nutrient balances are

good

and the only weed seed I think ever came in through it was one productive
and delicious tomato plant.

As for rice hulls, I've been trying them for a few years after they

showed

up in Dirtcraft's seed starting mix. I don't repot often so I don't know

they'll last as long as my soil mix needs to, but Cyclamen have been
happier in mixes with rice hulls than almost anything I've tried.

Currently

a lot (like 3x) cheaper than perlite here. I've seen a few nurseries

using

it as a top dressing for pots, haven't tried that myself. If anyone has
info on rice hull/perlite replacement ratios I'd love that info!

I've switched from peat to coconut coir to mostly composted local

forestry

waste for everything except carnivorous plants (and based on some advice
from a local grower, I'll switch them to coconut as soon as this bag runs
out), and it seems there's a shift from coir to more sustainable/local
stuff like forestry waste, peanut shells etc as nurserymen dial in their
formulae. Feeling the heartbreak of living in a place where 10,000+ acres
at a time of Lilium, Trillium, Cypripedium etc. get destroyed by
mountaintop removal coal mining, I'm trying to avoid using
stripmined/rainforest deforestation etc. materials in my growing media as
much as possible.

-joe

On Mon, Dec 18, 2023, 7:23 AM Tim Eck via pbs <
pbs@lists.pacificbulbsociety.net> wrote:

Luckily they quietly took the bad stuff - arsenic - out of pressure

treated

wood a few decades ago when a demographic study (of well water in

Formosa,

I think) showed it was proportionally carcinogenic at all levels. Now,

think, they only use copper naphthenate for fungicide in pressure

treating.

Personally, I am banking on The American Chestnut Foundation (TACF)
eventually solving the problem altogether because chestnut wood seems to
persist untreated for decades in ground contact.
For those interested, TACF has withdrawn its support for their

transgenic

chestnut, partially due to their dissatisfaction with the growth rate

using

a constitutive promoter (always on) for the OxO gene (destroys oxalic

acid

secreted by the blight fungus). But the departure from SUNY's

deregulation

request was precipitated by the discovery of a misidentification of the
clone they were testing early in the program. TACF will continue
investigating transgenic (but with wound induced promoters) as well as
hybridizing and biocontrol.
If anyone is interested in breeding blight resistant forest quality
chestnut trees, I have (free) seed for the final generation of a

breeding

program I have been working on for a few decades. The ideal plot would

about two acres of well-drained cornfield.
Tim

On Sun, Dec 17, 2023 at 9:29 PM Laura Grant via pbs <
pbs@lists.pacificbulbsociety.net> wrote:

We had a bad experience with composted " pine bark" delivered by a

local

supplier. After most of the truck load was spread around the favorite
plants we noticed some losses. When we came to the bottom of the pile

found labels that read "pressure treated".
Laura

On Sun, Dec 17, 2023 at 3:33 PM Jan Jeddeloh via pbs <
pbs@lists.pacificbulbsociety.net> wrote:

I used to get tree trimmer waste at my old place. Some of those tree
trimmers also do some maintenance and I once got a load that that

wasn’t

straight trees. It was filled with crap from blowing off parking lots
etc. I learned my lesson. Always ask what’s in the truck before they

dump.

Jan

On Dec 17, 2023, at 12:23 PM, Arnold Trachtenberg via pbs <

pbs@lists.pacificbulbsociety.net> wrote:

We had the company deliver a load of compost to our community garden

and

it was full of debris and garbage from street pick up.

I've never seen any lab work on the compost they sell. It may be

tested

different in CA, but not here in NJ.

I can imagine the petrochemicals, heavy metals and brake lining

debris

picked up when leaves are vacuumed up in the fall from our streets.

Arnold

On Sunday, December 17, 2023 at 02:54:59 PM EST, Tim Eck via pbs <

pbs@lists.pacificbulbsociety.net> wrote:

Good point. I knew it got hot enough to kill most pathogens but was

not

aware it decomposes pesticides. I rather doubt it destroys those
organo-halide bonds but they aren't so common anymore.

On Sun, Dec 17, 2023 at 2:38 PM Nan Sterman via pbs <
pbs@lists.pacificbulbsociety.net> wrote:

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

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.

On Dec 17, 2023, at 11:21 AM, Jane McGary via pbs <

pbs@lists.pacificbulbsociety.net> wrote:

As Mark mentioned, municipal compost in this area includes lawn

clippings, and I don't use it either for fear of herbicide residue.

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

bought bags of "garden topsoil" from certified organic sources for

this

purpose. The main things I avoid are bark, which appears to be

attacked

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

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

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

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.

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

this

kind of gardening.

Jane McGary, Portland, Oregon, USA

On 12/17/2023 8:18 AM, Robert Lauf via pbs wrote:
Regarding arborist debris, I'd be curious to know whether the

kinds

bacteria and fungi inhabiting half-dead trees would present a

problem

bulbs or if they are sufficiently host-specific that they are

harmless

potting media. For all I know, they might be the same microbes

working

composters.

Any mycologists out there who could weigh in on this?
Bob Zone 7
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