Sowing cacti seeds during offseason?

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LateBloomer
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Location: Curitiba, Brasil

Sowing cacti seeds during offseason?

Post by LateBloomer »

We all usually sow seeds spring or summer when temps are hot and for the most part this works perfectly however with the few 'difficult' seeds like saboae complex and E. horizonthalonius many growers have difficulty getting acceptable germination rates.

I have tried shaving seeds with success however with smaller seeds like bertholdii and even theresae this was too hard and I just sowed them without it since I had a fair amount even with lower germination I would have been satisfied.

I sowed the seeds first month of fall and have had a few very cold nights with most being around 10C. The seller mentioned that the seeds only had 6 months from harvest date and suggested I wait until they were a year old. This has shown to be effective when sowing these therasae and other saboae sp. with older seeds doing well and fresh seeds having very low germ rate.

HOWEVER don't most cacti fruits mature in the summer meaning they would be 'naturally sown' in fall/winter months? I believe that sowing during these months would result in more favorable conditions then sowing during the very hot temps. I haven't been able to test this theory with a control however my saboae seeds are all around 70% germ rate despite them all being fresh. I am still getting odd germination but perhaps cooler temps work better with some species similar to how poppy seeds need cold temps to germinate?

If someone that harvests own seeds could test this by sowing during different seasons to see if they break dormancy naturally without our help that would be awesome... I know many people sow during spring/summer due to extreme winter temps however maybe even a protected mid winter sowing indoors without additional heating?

Anyone already test this or have experience? I've sown in the winter last year without issues however had low germination which I think were seed quality.
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MrXeric
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Location: California, USDA zone 10a

Re: Sowing cacti seeds during offseason?

Post by MrXeric »

LateBloomer wrote: Mon May 30, 2022 10:11 pm
HOWEVER don't most cacti fruits mature in the summer meaning they would be 'naturally sown' in fall/winter months? I believe that sowing during these months would result in more favorable conditions then sowing during the very hot temps.
I would say most cactus seeds will just sit there after dispersal (whenever that may be) and wait for optimal conditions to occur to germinate.

Obviously, fruit ripening and seed dispersal highly depends on the species.
I've observed my Astrophytum ripen their fruits as soon as 18 days after flowering in the summer. As you know, astro seed germinates within a couple days, if not hours after sowing. My Astros throw out 3 to 4 flushes of flowers over the summer. Similarly with my Frailea (though those only bloom once per season for me).

In terms of controlled temperatures, there have been many studies showing that optimum germination temps are on the warmer side.
From Cacti Biology and Uses, edited by Park S. Nobel (2002) (pdf here):
For cacti, the optimal temperature for seed germination ranges from 17 to 34°C, with a mean of 25°C (Nobel 1988). Alternating temperatures give higher germination yields than constant temperatures (Rójas-Aréchiga and Vázquez-Yanes, 2000). For Opuntia species, optimum constant temperatures vary from 25 to 35°C (Mondragón-Jacobo and Pimienta-Barrios 1995). For Astrophytum myriostigma, germination rates are highest (80–98%) at temperatures from 20 to 25°C, and decrease at higher temperatures under conditions of diffuse light (Moreno et al. 1995).
Also:
However, the seeds of Echinocereus polyacanthus do not germinate in the winter, at the time of fruit ripening, suggesting that low temperatures or short days can induce dormancy for this species (Trujillo 1982).
See also this table:
cacti germ light and temp.PNG
cacti germ light and temp.PNG (99 KiB) Viewed 280 times
As you can see some species do have germination going on at temps as low as 10C, which you have observed with your sowing, but optimum germination occurs with warmer temps.

Recall also that in habitat the seeds more likely to germinate are those that make it beneath the protection of nursery plants, where temps and light are more mild and water is more abundant.
LateBloomer
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Location: Curitiba, Brasil

Re: Sowing cacti seeds during offseason?

Post by LateBloomer »

However, the seeds of Echinocereus polyacanthus do not germinate in the winter, at the time of fruit ripening, suggesting that low temperatures or short days can induce dormancy for this species (Trujillo 1982).

this is what I wanted to see... I would assume that other species would act similarly but maybe these 'hard' seeds are different?

Thanks for the reply.... I guess I'll do my own test when I harvest my own seeds...
keith
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Location: S. CA USA

Re: Sowing cacti seeds during offseason?

Post by keith »

I was able to germinate cactus seeds in Phoenix AZ in Winter on a south facing window in the garage. Now in CA I don't think they would do very well not hot enough and too humid. I guess a LED indoor setup and it wouldn't matter Winter would be made into Summer.
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greenknight
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Location: SW Washington State zone 8b

Re: Sowing cacti seeds during offseason?

Post by greenknight »

Most cacti grow in climates where winters are dry, they most likely sprout with the spring rains.

Anyway, if you provide artificial light and heat you can create optimum conditions for germination any time of year.
Spence :mrgreen:
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anttisepp
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Location: Suomi - Finland

Re: Sowing cacti seeds during offseason?

Post by anttisepp »

Ola! In our country many cacti-growers germinate seeds at beginning of winter and grow seedlings under artificial light, so when spring comes seedlings are relatively large to continue growth in shaded sun.
Cumprimentos
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