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I have a Cleistocactus vulpis-cauda in flower. With no other plant of same species I tried pollinating with whatever else was around. It took seed and I waited until the pod began to split. Tried sowing. It's been two weeks and nothing. Temp gets to 29C. Would these seeds be non-viable? I planted the seeds straight after harvesting without drying.

I must say, with as much as I know about cacti by now, I am still confused whether or not 'nonviable seeds' exist. I mean, do cacti actually produce empty shells that won't grow? I heard people claim this, but never actually saw it referenced.

Also, from the seeds I picked the other day, I decided I would dry them for a week before sowing so they would feel dryness before sowing. I thought they wouldn't realize there was anything different between wet fruit and a wet pot. Maybe that's nonsense, but that's how I imagined it at the moment.

I don't know myself. Some 3 years ago I noticed an E.subdenudata had produced seeds. Stored them (30+) with my other seeds in a cool dark place. Tried germinating this year and nothing. Physically they looked fine. Same story in that I only had one plant of the species. I've had seeds older than that which still work fine.

Two weeks is about the time most of the species I sow just start to germinate. For many it can take three or even four weeks before I start to give up. If I give up, then I just let the pot dry out and restart a few weeks later, to give them another chance. And again the next year. I do sow in an unheated greenhouse that gets quite warm during the day when I sow early April. Their second chance is early May, when it is even warmer. The nights are still chilly then.

Are the seeds that you have sown in a constant temperature of 29C, or does it get colder too? For most cacti in the 20C is fine, but 29C still is mostly on the high side if it is a constant temperature. The nights can be colder too. A difference of up to 20C between day and night is not a problem, probably even beneficial.

I have germinated Cleistocactus at around 70 degrees. Seeds germinated in 10 days. I don't think 85 degree temperatures (29c) would be necessary.

metsolt wrote: ↑Tue Jan 11, 2022 8:46 am I must say, with as much as I know about cacti by now, I am still confused whether or not 'nonviable seeds' exist. I mean, do cacti actually produce empty shells that won't grow? I heard people claim this, but never actually saw it referenced.

I think this is an interesting question. Does anyone knows anything about it? I was just wondering it when I saw this thread...I have myself seeds collected from a presumably self sterile species...asking myself if they will germinate, since they are the product of self-fecundation (?) or cross pollination with another species, which means that they can be non-viable...but, why produce seeds when they will not germinate?

I have seen two types of Non Viable seeds. The first are the seeds which are hollow, and without an embryo, mostly on opuntia species. The other is seeds that are lighter in color, mostly on echinopsis.

Aeonium2003 wrote: ↑Tue Jan 11, 2022 4:35 pm I have seen two types of Non Viable seeds. The first are the seeds which are hollow, and without an embryo, mostly on opuntia species. The other is seeds that are lighter in color, mostly on echinopsis.

That is interesting!
I haven't dealt with Opuntia much, I must admit they're not my favorite genus because of the glochids.
With the second type of seeds you mentioned, was that the whole fruit? Or only some? Has the fruit ripened fully with bad seeds?

mmcavall wrote: ↑Tue Jan 11, 2022 4:26 pm

metsolt wrote: ↑Tue Jan 11, 2022 8:46 am I must say, with as much as I know about cacti by now, I am still confused whether or not 'nonviable seeds' exist. I mean, do cacti actually produce empty shells that won't grow? I heard people claim this, but never actually saw it referenced.

I think this is an interesting question. Does anyone knows anything about it? I was just wondering it when I saw this thread...I have myself seeds collected from a presumably self sterile species...asking myself if they will germinate, since they are the product of self-fecundation (?) or cross pollination with another species, which means that they can be non-viable...but, why produce seeds when they will not germinate?

That is exactly what confuses me. I'm not sure why a plant would spend resources on making something that's not usable, but even if it happens, I'm sure there are chemical triggers to it.
What species/genus is that? Because even within the same species there are variations that are or aren't self-fertile, maybe yours is one of those that is self-fertile.

metsolt wrote: ↑Tue Jan 11, 2022 5:32 pm What species/genus is that? Because even within the same species there are variations that are or aren't self-fertile, maybe yours is one of those that is self-fertile.

I don't remember...have to check the seeds I've collected recently.
It's interesting to know that self-fertility can vary within the species. There are very few sources of information about it. The seed list of ADBLPS brings information about self-fertility and you can see there that there is variation within the species...but besides that I can't find any additional information...it's a shame, since this is an important information for we collectors...maybe we could start a thread listing self fertile and self sterile species?

mmcavall wrote: ↑Tue Jan 11, 2022 7:19 pm I don't remember...have to check the seeds I've collected recently.
It's interesting to know that self-fertility can vary within the species. There are very few sources of information about it. The seed list of ADBLPS brings information about self-fertility and you can see there that there is variation within the species...but besides that I can't find any additional information...it's a shame, since this is an important information for we collectors...maybe we could start a thread listing self fertile and self sterile species?

If you take Lophophora williamsii, for example, its locality determines whether or nor it's self fertile. I might have remembered this wrong, but I think Northern varieties are the ones that are self fertile...?
That would be good, yes, but maybe there already is an abandoned thread about this?

metsolt wrote: ↑Tue Jan 11, 2022 5:32 pm

Aeonium2003 wrote: ↑Tue Jan 11, 2022 4:35 pm I have seen two types of Non Viable seeds. The first are the seeds which are hollow, and without an embryo, mostly on opuntia species. The other is seeds that are lighter in color, mostly on echinopsis.

That is interesting!
I haven't dealt with Opuntia much, I must admit they're not my favorite genus because of the glochids.
With the second type of seeds you mentioned, was that the whole fruit? Or only some? Has the fruit ripened fully with bad seeds?

Usually it's just a few seeds. Sometimes up to 1/10 of the batch.

Aiko wrote: ↑Tue Jan 11, 2022 3:02 pm Are the seeds that you have sown in a constant temperature of 29C, or does it get colder too?

It peaks at around 29C during day because it's been quite hot lately. For germination I use small 150ml containers inside a larger container which has a 7W reptile heat mat (manual thermostat) stuck to the bottom. This spring/summer is the first time I used the method described here:

https://youtu.be/NvPPawMPQlM

It seems to work well but I worry combination of too much heat & moisture can (has?) cause seed rot.

Aeonium2003 wrote: ↑Tue Jan 11, 2022 4:35 pm I have seen two types of Non Viable seeds. The first are the seeds which are hollow, and without an embryo, mostly on opuntia species. The other is seeds that are lighter in color, mostly on echinopsis.

The seed I obtained from the cross-pollination were brownish in colour and black at the open end. Normal for this species? Too small to crack open to see if anything inside. Perhaps I should have let seeds dry before planting? I have more so I can wait and try again later.

Cleistocactus seeds are usually black. I planted seeds right away, it doesn't seem to matter. Did you harvest the fruit when it was fully red and cracking open?

Aeonium2003 wrote: ↑Wed Jan 12, 2022 2:18 am Cleistocactus seeds are usually black. I planted seeds right away, it doesn't seem to matter. Did you harvest the fruit when it was fully red and cracking open?

Not with first pod but later pods that split looked about the same. Coincidentally I got C.strausii to set seed after cross-pollinating. Pod not fully ripe but cracked it open anyway. Took photos it and the C.vulpis-cauda. Different in shape and size.

FWIW here are the pics I previously attempted to upload.