Synthetic seeds

Lee Poulsen via pbs pbs@lists.pacificbulbsociety.net
Sat, 10 Jan 2026 17:44:32 PST
That PPM sounds interesting. I’ve tried several other materials and none seem to stop something from growing after a long time. 5 months is great. Thanks for that information.

--Lee Poulsen
San Gabriel Valley, California, USA - USDA Zone 10a
Latitude 34°N, Altitude 340 ft/100 m

> On Jan 9, 2026, at 05:30, Tim Eck via pbs <pbs@lists.pacificbulbsociety.net> wrote:
> 
> Bob,
> The only nuance you are missing is the fact that the gel medium contains *Plant
> Cell Technologies*' nearly magical concoction "*PPM*" as well as sugar.
> PPM (plant propagation medium?) is a mixture of two chemicals that are
> persistent over time and temperature and prevent *anything *except plants
> from growing.  It kills fungi, bacteria, chromista, animalia, etc., which
> means no mold or mildew will develop.
> But you are otherwise correct.  No direct connection to an energy source,
> so it will start slowly and need exposure to light, but it doesn't need a
> sterile environment but can be directly planted in a seed tray.  I assume
> the PPM will eventually leach out with watering.
> I bought some PPM once to protect chestnut seeds from mold while
> overwintering and I can tell you two things from that experiment - it is
> expensive to make five gallons of solution and those were the only bags
> that had zero mold after five months in the cooler.  I also tried hydrogen
> peroxide, bleach, povidone iodine (betadine), benzalkonium chloride, Star
> San, etc.
> It may be worth some members buying some to try on seed or cuttings that
> are prone to mold or mildew.
> Good Luck,
> Tim
> 
> 
> On Fri, Jan 9, 2026 at 12:43 AM Robert Lauf via pbs <
> pbs@lists.pacificbulbsociety.net> wrote:
> 
>> If I understand this correctly, the synthetic seeds might be larger and a
>> bit easier to handle, but "treating them like seeds" is in many ways
>> problematic.  Treating them like orchid seeds might be a better analogy,
>> for two reasons:1. Normal seeds have a seed coat to prevent dehydration of
>> the embryo.2. Normal seeds contain endosperm, which the embryo lives on
>> until it makes leaves and starts photosynthesizing.
>> So it would seem that the synthetic seed is roughly analogous to a
>> germinating orchid seed at the protocorm stage, and you couldn't take that
>> and plant it in dirt.  It still needs to be in sterile medium containing
>> sugar.  If these bodies are somehow encapsulated and removed from the
>> culture medium just for shipping, I would think they would be difficult to
>> sterilize, and if not sterilized, they would immediately contaminate the
>> new medium and you'd have a jar full of mold.  Maybe I'm missing something
>> here.  If you already have successful propagules of the desired plant in a
>> flask, why not leave them in the flask until they are little plants with
>> leaves and capable of living in the open?
>> Embryo rescue, which I have done, starts with a seed from two parents that
>> are dissimilar enough that the pod parent doesn't recognize it as her
>> offspring and doesn't make any endosperm.  But the embryo is in fact alive
>> and viable, but just like an orchid seed (except usually bigger).  Imagine
>> a Hipp seed but with practically no "yolk" in it.  So you surface sterilize
>> in diluted bleach or hydrogen peroxide, and sow on orchid medium to supply
>> the sugar, and voila.  This is probably why it's so easy to make
>> intergeneric orchid hybrids, because orchid seeds have all been germinated
>> by this method anyway.
>> Full disclosure:  I'm not a botanist, nor do I play one on TV (apologies
>> to Marcus Welby...)  If you don't get that joke, you are probably less than
>> 70 years old.
>> Bob   Zone 7   warm with rain on the way; daffs and hyacinths starting to
>> sprout
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