Any concerns with these species in unheated greenhouse?

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AnthonyH
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Any concerns with these species in unheated greenhouse?

Post by AnthonyH »

I am migrating my indoor cactus and agave collection to a greenhouse (ideally year round) as it's gotten too large. I'm not proposing to heat or insulate the greenhouse. Would you have any major concerns about these being out (bone dry) in a greenhouse throughout the winter in London?

I'm prepared to take a degree of risk because I think the most expensive of these came to a whopping £3.50. That said, I don't want to kill any particular plant if it's obvious it definitely won't survive. I have some space in the house but very, very little.

I would expect -7 or -8 on the absolute worst nights, but very rare.

CACTI
- Stenocereus Pruinosis
- Ferocactus Hystrix
- Ferocactus Latispinus
- Mammillaria Pringlei
- Cereus Forbesii/Peruvianus (who knows?) Spiralis
- Opunti Dejecta
- Acanthocereus Tetragonus (possibly a monstrose form - warty areoles, no spines)

AGAVES
- Salmiana
- Fourcroydes
- Sisalana
- Filifera

I understand that my Myrtillocactus, Pilosocereus and Gasterias are out of the question - but let me know if you disagree.

Thank you.
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Aiko
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Re: Any concerns with these species in unheated greenhouse?

Post by Aiko »

Of these, I suspect only the Ferocactus, the Mammillaria and Agave will survive.

The Agave filifera for sure. My 15 years old self sown A. filifera have survived the last few winters in an unheated greenhouse. A year ago we got a real cold winter, and they seem to have survived this easily still.

Pilosocereus and Gasteria are indeed not suited for frost. Although the Gasterias can take a bit of frost late autumn or early spring, but not a prolonged cold.
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AnthonyH
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Re: Any concerns with these species in unheated greenhouse?

Post by AnthonyH »

Thank you. Do the clumnar cacti not do so well then?
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Re: Any concerns with these species in unheated greenhouse?

Post by rodsmith »

AnthonyH wrote: Sat Apr 20, 2019 10:26 pm Thank you. Do the clumnar cacti not do so well then?
They are generally less able to cope with very low temperatures.
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Growing a mixed collection of cacti & other succulents; mainly smaller species with a current emphasis on lithops & conophytum.
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Paul in Essex
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Re: Any concerns with these species in unheated greenhouse?

Post by Paul in Essex »

I've had Agave salmiana and filfera growing outside unprotected from the elements through -8C so kept dry they'll be fine. The other two are more tender species but may well be fine kept dry.
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AnthonyH
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Re: Any concerns with these species in unheated greenhouse?

Post by AnthonyH »

rodsmith wrote: Sun Apr 21, 2019 7:46 am
AnthonyH wrote: Sat Apr 20, 2019 10:26 pm Thank you. Do the clumnar cacti not do so well then?
They are generally less able to cope with very low temperatures.
Thank you. Do you agree that the stenocereus would need to be taken in then? Want to minimise the number taken indoors but will take in if needed.
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AnthonyH
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Re: Any concerns with these species in unheated greenhouse?

Post by AnthonyH »

And has anyone any experience with Optunia/Nopalea Dejecta? On the one hand it is from Cuba, which doesn't suggest cold tolerance. On the other hand, Opuntias are generally quite tough battleaxes which makes me think it might well survive?

Does anyone else keep this species?
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rodsmith
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Re: Any concerns with these species in unheated greenhouse?

Post by rodsmith »

AnthonyH wrote: Sun Apr 21, 2019 10:39 am
rodsmith wrote: Sun Apr 21, 2019 7:46 am
AnthonyH wrote: Sat Apr 20, 2019 10:26 pm Thank you. Do the clumnar cacti not do so well then?
They are generally less able to cope with very low temperatures.
Thank you. Do you agree that the stenocereus would need to be taken in then? Want to minimise the number taken indoors but will take in if needed.
I would recommend you take it in.
Rod Smith

Growing a mixed collection of cacti & other succulents; mainly smaller species with a current emphasis on lithops & conophytum.
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Re: Any concerns with these species in unheated greenhouse?

Post by habanerocat »

I don't heat either. I try to grow the species that will survive the cold. Climate change, cost, for any number of reasons.

But you do need some backup frost protection for the really cold nights, otherwise you could loose your complete collection. Always plan for the unforeseen, being busy, work, God forbid illness, whatever.

Automatic frost protection is a must.
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Re: Any concerns with these species in unheated greenhouse?

Post by KathyM »

The Gasteria might be worth trying in the greenhouse if you need to. I've only ever grown common ones and found that they might not look great but they can survive.
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