Seed Sowing Time!

peterb · Post by **peterb** » Fri Nov 17, 2006 4:45 am

Hi- One of the things I like about growing cacti at 7,000 feet in Santa Fe's wacky climate is there's a weekend sometime between now and mid-December set aside for sowing Pediocactus, Touymeya and Sclerocactus seed.They are in pots in a germination chamber and left outside all winter. Pedios germinate when it is still freezing at night, sometimes as early as the first week of March. When cold stratified for several months germination rates are very high. Some of the Pediocactus simpsonii v. indraianus seed I'm sowing is 11 years old, intentionally kept around to test the "old seed germinates better than new" theory re: Pedios. T. papyracantha, Sclerocactus parviflorus and a few other Pedio seeds might just get sown this weekend, I'm not sure.

peterb

Post by **daiv** » Fri Nov 17, 2006 5:07 am

Peter, you're a better seed grower than I. Getting those guys to bloom is quite a deal. Keep going!

iann · Post by **iann** » Fri Nov 17, 2006 7:40 pm

I'm not quite sowing yet, but I am looking at seed lists

I do have one tiny Pediocactus seedling that recently sprouted up amongst a bunch of Mammillarias long after I had decided they were finished with germination and re-used the tray!

Post by **daiv** » Sat Nov 18, 2006 1:11 am

Ha Iann, that has been my experience. The only ones that survived for me are those that I figured didn't make it and neglected them.

Plantcelot · Post by **Plantcelot** » Sat Nov 18, 2006 9:35 am

11 years old, intentionally kept around to test the "old seed germinates better than new" theory re: Pedios. T. papyracantha, Sclerocactus parviflorus and a few other Pedio seeds might just get sown this weekend, I'm not sure.

Hi peterb, that sounds very interesting! I will be sowing seeds for the first time during the weekend and I plan on saving half of my seeds for the future. I certainly hope that the theory works.

peterb · Post by **peterb** » Sat Nov 18, 2006 4:41 pm

Hi Plantcelot-

I am under the impression that age of cactus seed has widely varying effects on viability depending on the genus. In this part of the southwest I've talked to several growers who are convinced that Pediocactus and Sclerocactus seed germinates best after several years of dry storage. But I know there are other cacti that have much higher germination rates if the seed is sown right out of the fruit.

On the other hand, I think, generally, cactus seed is "designed" to sit around for a while without too much impact on germination, since the habitats are often inhospitable to germination for many years.

Anyone with more experience or data?

peterb

peter · Post by **peter** » Sat Nov 18, 2006 5:26 pm

peterb wrote:But I know there are other cacti that have much higher germination rates if the seed is sown right out of the fruit.

Hi
That is exactly my experience, so I prefer always new seeds.

On the other hand, I think, generally, cactus seed is "designed" to sit around for a while without too much impact on germination, since the habitats are often inhospitable to germination for many years.

I agree, but that "designed feature" is not a must in cultivation.
OK, on the other hand, I know the facts about Opuntia seeds and temperaturs.

Best regards

parodias · Post by **parodias** » Sat Nov 18, 2006 5:41 pm

It is commonly accepted (is it?) that seeds need an "ageing" stage to allow germination inhibitors to be broken down by natural conditions (low temps, scarification, possible moisture+freezing etc)

The controversial observations here make the matter even more confusing. A number of species seem to germinate abundantly when sowed freshly from the fruit but then seem to provide no germinating yields anymore after having rested for some weeks (days?). They also seem to go back to germination after some months of normal storage or even when triggered by cold. I've seen this happen in Rebutia and Parodia sensu strictu.

The age of the seeds is another field where actually nothing is known for sure. Microsperm Parodia are claimed to lose their germination power after one year but several sowings that did not yield any germination where just put under the greenhouse benches and forgotten for 3 years (they got pretty cold feet in winter!) and then suddenly they started germinating, not "en masse" but at least for 40-60%. So actually this experiment made me wonder once again. Other people in the same field of interest came to similar conclusions ..
FWIW

iann · Post by **iann** » Sat Nov 18, 2006 9:42 pm

t is commonly accepted (is it?) that seeds need an "ageing" stage to allow germination inhibitors to be broken down by natural conditions

Not commonly accepted at all and certainly not accepted by me. Many species of cactus and virtually all mesembs (there are a couple of known exceptions) germinate at very high rates straight off the plant.

There are several types of well studied dormancy in seeds. One is by chemical inhibition by the fruit pulp so that seeds do not germinate until they have been eaten or otherwise well cleaned. Another is the "immature embryo" type where seeds will not start to germinate until they have spent some weeks or months out of the seed capsule, usually in warm moist conditions. Another very widespread dormancy, although not so common in cultivated cacti, is chemical inhibition which is broken by a period of cold moist conditions. Other dormancies that can be harder to pin down or break involve very tough seed coats designed to be broken by digestion, periods in a river, or simply over a long time. And one last type of dormancy that may be relevant to Parodias findings is a dormancy that only takes hold some time after seed maturity, so that fresh seed germinates easily but any stored seed requires appropriate treatment, frequently cold stratification. Several dormancies may occur in the same seed, obviously a tough seed coat can be combined with anything, but seed that requires a warm period to mature the embryo followed by a cold period to break dormancy is very common.

Most cacti outside the Opuntioids do not show strong signs of any of these dormancies. Many Opuntioids show erratic and slow germination, but in my experience they just have tough coats and germinate readily if you can get around this. The Pediocactus clan appear to be similar, there is no simple warm or cold or time treatment that will reliably germinate them but techniques like nicking, soaking, and acid all help greatly. Others have reported that cold treatment is necessary for some species but more commonly it is found that alternating cold/warm treatment and especially freezing is effective, all symptoms of an impermeable seed coat. Warm and cold stratification dormancies in non-cactus species are generally found in herbaceous or deciduous plants, including geophytes, from climates with cold winters.

I have never found a type of seed that reliably germinates better after any aging more than a few months. I have found some that becomes unviable very quickly, sometimes in just a few months, but most seems to store well for several years as a minimum. Warm moist storage is fatal for most seed in months or a few years at most.

Mesemb seed mostly germinates at close to 100% straight out of the capsule. Mesemb seed capsules have disallowed - see forum rules some extremely complex physical mechanisms to release their seed either over an extended period of time, at a particularly suitable (ie. wet) time, or both, and further seed dormancies would be redundant. Some species do seem to mature their seed capsules some time before the seed is mature, and it has been observed that seed from the same capsule will germinate in two or three waves a week or two apart.

peter · Post by **peter** » Sat Nov 18, 2006 11:52 pm

Hi all

Here two interesting articles about that theme.

From the DKG (Don't worry, the text is in english)
http://www.deutschekakteengesellschaft. ... humi2.html

And a text in pdf format
http://www.scielo.org.ar/pdf/phyton/n1/n1a26.pdf

Best regards

Plantcelot · Post by **Plantcelot** » Sun Nov 19, 2006 10:10 am

All the info and links are very interesting. Too bad that there is no specific data lists on the viability of all of the diverse types of cactus and succulents seeds. Most of the information available are for grains and vegetables. It will be great if some of peterb’s seeds could germinate, at least we will know about the species that could germinate after 10 years. I don’t have any old seeds to test but will save some of mine to test eventually. I was trying to find some info on the best way to store my seeds and got these two interesting links:

Seed Viability

Introduction to Seed Viability

Good Thread