Too hot to germinate?

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Too hot to germinate?

Postby steve.smith » Tue Jan 21, 2014 4:54 pm

Is there a maximum temperature beyond which cacti seeds will not germinate?

The reason I ask is that I have a non-thermostat propagator and on putting a max-min thermometer in discovered the temperature was occasionally reaching 95F. I have 36 individual square pots in there, of which 7 have so far germinated after 10 days, but i thought maybe the high nineties might be a bit excessive for certain types.

If they have been subjected to "too high" temperatures is it worth shifting them to a temperature regulated propagator at 75 to 80Fish or will the seed have been destroyed?
Steve Smith

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Re: Too hot to germinate?

Postby iann » Tue Jan 21, 2014 5:00 pm

There are over 1,000 species of cactus. Which ones were you thinking of?
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Re: Too hot to germinate?

Postby steve.smith » Tue Jan 21, 2014 5:06 pm

They are a mixed bunch:
Ariocarpus
Aylostera
Aztekium
Copiapoa
Coryphantha
Discocactus
Escobaria
Echinopsis
Parodia
Ferocactus
Frailea
Lophophora
Melocactus etc.
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Re: Too hot to germinate?

Postby iann » Tue Jan 21, 2014 5:12 pm

None of them will be damaged at 95F, but some will almost certainly not germinate if kept at that sort of temperature, even just for a few hours of each day.

For those that don't germinate within a couple of weeks, drop the temperature. Try to drop the night temperature in particular. 75F - 80F during the day is a good figure, but if that still isn't good try dropping the night temperature to 60F or even cooler. Aylostera seems like one that would prefer a cooler temperature, but possible also the Escobaria, and maybe Echinopsis and Parodia depending on which species.
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Re: Too hot to germinate?

Postby steve.smith » Tue Jan 21, 2014 5:19 pm

Thanks for that Ian. This was a "spare" propagation unit I am using and I must admit I did not realise how warm it got in there! I will give them a week and move them to a better controlled unit if I don't get germination.
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Re: Too hot to germinate?

Postby iann » Tue Jan 21, 2014 5:22 pm

Did the Melocactus germinate? They're a group where most at least are supposed to germinate well at high temperatures? I don't know because I've never grown them. Same for Frailea. I do find that Ariocarpus germinate well at the high end of the temperature range, althoiugh they can still be slow.
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Re: Too hot to germinate?

Postby steve.smith » Tue Jan 21, 2014 5:31 pm

So far in these conditions these have germinated:
Cochemiea poselgeri
Copiapoa coquimbana
Coryphantha vivipara
Echinocactus parryi
Eriosyce esmeraldana
Frailea cataphracta
Gymno riojense
Lobivia aurea
Lophophora lutea
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Re: Too hot to germinate?

Postby CactusFanDan » Tue Jan 21, 2014 7:25 pm

Ariocarpus, Aztekium, Copiapoa, Discocactus, Frailea, Lophophora and Melocactus probably appreciate the high temperatures more than any of the others on that list. Ariocarpus, Aztekium and Discocactus especially love really high heat.
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Growing an eclectic mix of Cacti, with a few Caudiciforms and other Succulents. Also interested in African bulb plants.
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Re: Too hot to germinate?

Postby iann » Tue Jan 21, 2014 7:45 pm

CactusFanDan wrote:Ariocarpus, Aztekium, Copiapoa, Discocactus, Frailea, Lophophora and Melocactus probably appreciate the high temperatures more than any of the others on that list. Ariocarpus, Aztekium and Discocactus especially love really high heat.

I bet the Aztekium germinated already and you just can't see them :lol:
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Re: Too hot to germinate?

Postby DaveW » Tue Jan 21, 2014 7:47 pm

I copied these tables out some years ago:-

GERMINATION2.jpg
GERMINATION2.jpg (99.1 KiB) Viewed 245 times


GERMINATION.jpg


As you can see high temperatures can inhibit germination if much above the optimal temperature. 25C mentioned as the mean temperature = 77F. As Ian says cooler night temperatures mimicking day and night fluctuations in habitat can often be beneficial.
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