sustainable potting media

Eric via pbs pbs@lists.pacificbulbsociety.net
Mon, 18 Dec 2023 08:04:22 PST
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 it
> 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 if
> 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, I
>> 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 be
>> 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 we
>>> 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
>>> 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.
>>>>>> 
>>>>>>> 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.
>> 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:
>>>>>>>>  Regarding arborist debris, I'd be curious to know whether the
>>> kinds
>>>> of
>>>>>> 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.
>>>>>>>> Any mycologists out there who could weigh in on this?
>>>>>>>> Bob  Zone 7
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