Overwintering cacti outside tips

For the discussion of topics related to the conservation, cultivation, propagation and exhibition of cacti & other succulents.
Forum rules
For the discussion of topics related to the conservation, cultivation, propagation and exhibition of cacti & other succulents only.

Please respect all forum members opinions and if you can't make a civil reply, don't reply!
NaZzAtAzEr
Registered Guest
Posts: 90
Joined: 13 Jan 2020
Branch: NORTH SURREY
Country: United Kingdom
Role within the BCSS: Member

Overwintering cacti outside tips

Post by NaZzAtAzEr » Tue Aug 25, 2020 6:12 pm

Hi, I'd like to keep some cacti outside this winter as I have bought too much and won't have space inside!
  • I have Winter Hardy
  • 1 Aloe Vera
  • 2 Anacampseros Filamentosa
  • 3 Ariocarpus kotschoubeyanus frost hardy to -10°C[/b]
  • 4 Astrophytum Myriostigma -7°C for short periods
  • 5 Austrocylindropuntia Vestita Cristata Protect from severe frost
  • 6 Crassula Ovata hardy to -1° C.
  • 7 Crassula Springtime hardy to -1° C
  • 8 Echeveria Agavoides Cristata -3.9° C
  • 9 Echinopsis 'Sierra Skyline' varies from -5°C to  -12° C 
  • 10 Echinopsis subdenudata hardy to -7° C
  • 11 Ferocactus Glaucescens -3.9° C
  • 12 Ferocactus histrix
  • 13 Ferocactus Wislizeni var. Herrera
  • 14 Gymnocalycium Friedrichii Quite frost resistant if kept dry -10° C 
  • 15 Gymnocalycium Kroenleinii ssp. Funettae
  • 16 Haworthia Vicosa
  • 17 Kalanchoe Tomentosa
  • 18 Lithops Aucampiae They require a minimum temperature 5°C (But will take a light frost and are hardy down to -7° C for short periods if they are in dry soil). 
  • 19 Lobivia Ferox hardy to -5° C)
  • 20 Mammilaria Lloydii -1.1 °C
  • 21 Mammillaria Polythele f. Nudum hardy to -5°C if kept dry
  • 22 Matucana Madisoniorum minimum temperature of 10° C
  • 23 Myrtillocactus Geometrizans 0
  • 24 Notocactus Turecekianus 0
  • 25 Opuntia rufida hardy to -5° C 
  • 26 Oreocereus Trollii/Celsianus down to 10°
  • 27 Peperomia caperata 'Abricos'
  • 28 Peperomia Columnella 10 °C. Protect from frost
  • 29 Pilea Mollis
  • 30 Rebutia Minuscula hardy to -7° C
  • 31 Rubber Plant (ficus elastica)
  • 32 Syngonium 'Neon Robusta'
  • 33 x Graptoveria ‘Kew Marble’
  • 34 x Graptoveria ‘Milky Way’
  • 35 Thelocactus Hexaedrophorus hardy to -7° C for short periods
  • 36 Thelocactus Hexaedrophorus
  • Euphorbia bupleurifolia x susannae  It needs to be kept warm
  • Gymnocalycium saglionis / pflanzii
  • Mammillaria haageana Hardy down to -4°C.
  • gymnocalycium erinaceum hardy to -12° C 
  • Gymnocalycium anisitsii hardy to -5 C ° C
  • Crassula plegmatoides hardy as low as -5° C
  • Bulbine mesembryanthemoides
  • Euphorbia bupleurifolia
  • Euphorbia meloformis variegated
I researched the hardiness for these cacti and I am able to protect from frost. I have a small plastic polytunnel that can fit them all in, and I'll stop watering them soon to reduce chance of rot. I read that humidity can cause them to rot so any advice?
esp
BCSS Member
Posts: 602
Joined: 20 Dec 2015
Branch: BIRMINGHAM & District
Country: UK
Role within the BCSS: Member
Location: Birmingham, UK
Contact:

Re: Overwintering cacti outside tips

Post by esp » Wed Aug 26, 2020 10:39 am

Take minimum temps as vague guides only - you will often be able to find different, contradictory minima for species. Minimum temp figures obtained from US growers are often geared towards extremely brief freezes of a few hours only, followed by rapid daytime warming. These may be a lot less challenging for plants than the UK's more prolonged cold (and humid) periods.

Low humidity, a quick drying compost with a high mineral content and ventilation will help as well as keeping the temperature up. You may also get overheating problems with a small polytunnel if it's in a sunny spot. Having a dry, waterproof base will also help, if you can prevent water coming in (e.g. on concrete or tarmac, rather than on soil).

Having plants on a bench or table rather than on the ground will also help, and should reduce any slug / snail problems.

With some of your plants, I wouldn't be keen on trying the poytunnel - slow growing expensive plants (e.g Ariocarpus) and more tender plants (e.g. Matucana madisoniorum).

As previously mentioned, overwintering indoors, even if it's dark (but cool) will be a safer bet for many of your plants.

If you are placing plants outside, I'd try to take back-up cuttings to keep indoors if possible, e.g. for Crassulaceae and clustering / offsetting species. Ideally do this in spring or early summer :shock:
User avatar
KarlR
BCSS Member
Posts: 539
Joined: 13 Oct 2014
Branch: None
Country: Norway
Location: Kristiansand, Norway

Re: Overwintering cacti outside tips

Post by KarlR » Wed Aug 26, 2020 10:43 am

Where do you live? You say you are able to protect from frost - does that mean you live somewhere you don't get frost or do you mean you will install some form of heating?

Most cacti from somewhere that is not close to the equator will survive frost (exceptions etc). Some may blemish if exposed to freezing temps. The key is definitely to keep them bone dry throughout winter. Tolerating short spells of frost and surviving for longer periods in freezing temps are two different things. A lot fewer will tolerate the latter than the former.

Most "other" succulents are less tolerant of freezing temps, but a lot of the South African ones will tolerate short spells below freezing. The important thing is that the soil is bone dry and that the period spent in freezing temps is short.

You could always try unpotting the plants, brushing off all the soil and putting them somewhere dark and cool for the winter. That might well be safer and more successful than keeping them outside.
User avatar
Phil_SK
Moderator
Posts: 5083
Joined: 11 Jan 2007
Branch: MACCLESFIELD & EAST CHESHIRE
Country: UK
Role within the BCSS: Forum Moderator
Location: Stockport, UK

Re: Overwintering cacti outside tips

Post by Phil_SK » Wed Aug 26, 2020 11:29 am

One other thing worth doing before you commit to any of these plans or suggestions is to reexamine your indoors space. Cacti and, to a certain extent, many other succulents are very tolerant of unpromising indoor locations provided you can keep them dormant (ie cool and dry). You say that you won't have space inside but are you thinking only of the windowsills where they might grow in summer? If your home is big enough/family small enough to have any unheated rooms or space you can use it - porch, under the stairs, spare bedroom, utility rooms are all fine and, if dormant, light levels aren't a problem so they can go in cupboards, under spare beds on shelves well away from windows. The tricky bit can be getting the plants dry through Sept/Oct when they do still need good light (and getting them used to bright light without burning in the spring). For a few years I overwintered my plants in a cellar!
Phil Crewe, BCSS 38143. Mostly S. American cacti, esp. Lobivia, Sulcorebutia and little Opuntia
NaZzAtAzEr
Registered Guest
Posts: 90
Joined: 13 Jan 2020
Branch: NORTH SURREY
Country: United Kingdom
Role within the BCSS: Member

Re: Overwintering cacti outside tips

Post by NaZzAtAzEr » Wed Aug 26, 2020 3:54 pm

KarlR wrote:
Wed Aug 26, 2020 10:43 am
Where do you live? You say you are able to protect from frost - does that mean you live somewhere you don't get frost or do you mean you will install some form of heating?
No, I thought if they were covered, then the frost wouldn't touch them? It won't be heated and they are on a garden table with the cheap plastic polytunnel.

I think I will resort to keeping them in my corner of my room, I have a few shelves that they can go on, to be forgotten about for the winter, and I'll be at uni (home at the weekends) so I can reduce the temperature in my room 5 days a week. I don't have any cool place in the house. I do also have places to keep them under grow lights but that space is really limited.
User avatar
KarlR
BCSS Member
Posts: 539
Joined: 13 Oct 2014
Branch: None
Country: Norway
Location: Kristiansand, Norway

Re: Overwintering cacti outside tips

Post by KarlR » Wed Aug 26, 2020 4:08 pm

They'll be protected from wind chill, but if it's below 0 outside it'll most likely be freezing inside that polytunnel too. Particularly if it's overcast or during night.

I think keeping them inside is the best option. The conditions you mention don't sound too bad. You could always move them outside when you're home, weather permitting.
NaZzAtAzEr
Registered Guest
Posts: 90
Joined: 13 Jan 2020
Branch: NORTH SURREY
Country: United Kingdom
Role within the BCSS: Member

Re: Overwintering cacti outside tips

Post by NaZzAtAzEr » Thu Aug 27, 2020 8:28 pm

Just had another thought, would keeping them in an unheated, uninsulated, weather-sealed shed be ok or is that too cold?
Mal L
BCSS Member
Posts: 332
Joined: 28 May 2011
Branch: MACCLESFIELD & EAST CHESHIRE
Country: UK
Role within the BCSS: Member
Location: Stockport, UK

Re: Overwintering cacti outside tips

Post by Mal L » Fri Aug 28, 2020 10:08 am

If it is uninsulated and unheated then the shed is not going to be that fundamentally different from your polytunnel idea, except much more wind-resistant and therefore far less risky. You would probably get protection from a marginal frost that lasts a few hours, but during a longer sustained freeze there is nothing to stop the temperature inside the shed eventually equalising with the temperature outside.
Malcolm
Stockport, UK
Member of Macclesfield & East Cheshire BCSS Branch

Collection mainly of cacti, though interested in a much wider variety of plants than I can accommodate!
esp
BCSS Member
Posts: 602
Joined: 20 Dec 2015
Branch: BIRMINGHAM & District
Country: UK
Role within the BCSS: Member
Location: Birmingham, UK
Contact:

Re: Overwintering cacti outside tips

Post by esp » Fri Aug 28, 2020 10:48 am

Mal L wrote:
Fri Aug 28, 2020 10:08 am
If it is uninsulated and unheated then the shed is not going to be that fundamentally different from your polytunnel idea, except much more wind-resistant and therefore far less risky. You would probably get protection from a marginal frost that lasts a few hours, but during a longer sustained freeze there is nothing to stop the temperature inside the shed eventually equalising with the temperature outside.
The shed may be very dry inside, so another benefit.
It still won't provide more than marginal help against sustained sub-zero spells.
Andyh
BCSS Member
Posts: 139
Joined: 25 Dec 2015
Branch: BIRMINGHAM & District
Country: United Kingdom

Re: Overwintering cacti outside tips

Post by Andyh » Fri Sep 04, 2020 8:59 pm

Its great researching isnt it! Ive done similar and overwintered many in cold greenhouse. Just some bubble wrap around part of grow area. eg low down. Under table there on and wooden planks around pots. Fleece if v cold. Many are now planted out and will just have a winter cover to stop rain. As someone suggested if its minus outside it will be minus inside too....just less the damp and wind.
If we had extreme cold...minus 5 below ive used parafin heater when it dropped to minus 10!
Id suggest making sure pots dry out and only risk those that can go to lower temps eg minus 5 or below.
Many minus 1s might be ok for odd night but can they cope with weeks? Some on llifle website say things like tollerates cold but prone to rot...im avoiding those! Keep such indoors or in heated ghouse.
Post Reply