Cold-hardy cacti

Cold-hardy cacti are enjoying increasing popularity. Not least because they are relatively easy to care during the winter months and require no special accommodation. In consideration of some important facts, they can endure all year round protected from rain in the garden on the terrace or on the balcony, and reward us every year again with the most beautiful flowers. Not everyone can afford a greenhouse or has the financial means of buying one and heating it in the winter.
A collection of cold-hardy cacti may also have a special charm, and the currently available species and hybrids can be a delight for any collector's heart.
On the following page I would like to give some useful experiences about cold-hardy cacti and complete it with a list of some recommendable cold-hardy cati.

 

What is special about cold-hardy cacti?

What do I have to mind?

How survive cold-hardy cacti the winter?

What care do cold-hardy cacti need?

Recommendable cold-hardy cacti

 

 

What is special about cold-hardy cacti?

Cold-hardy cacti are those cacti wich are able to reduce their cell sap and the volume of water in their body so much that temperatures below 0°C (32°F) can not demage the plant. The cactus stores sugar in its cells and reduces therefore the freezing point of water in its cells. So the cactus prevent itself from freezing.
To achieve this these plants don't take any water at the beginning of the cold season in fall. The existing water in the body is converted by photosynthesis into sugar. Due to the sugar which is stored in the cells the green epidermis change its color into red, brown or almost black. This process is absolutely normal and serves to protect the plants. Such prepared plants can survive the winter almost with any further intervention. These plants get another protection through the snow that covers them this provides an insulating layer against cold temperatures and cold winds.
The main range of the species is located in the United States of America up to southern Canada. But also the higher located cactus plants from Mexico and the Andes in South America are able to survive a short frost period.
It is important that the temperature rises during day time again up to 10°C (50°F).

 
Echinocereus baileyi in June   Echinocereus baileyi in December
     
 
Opuntia rutila in May   Opuntia rutila in December

 

 

What do I have to mind?

To grow successfully cold-hardy cacti in cold regions (e. g. Germany) you have to observe some rules. Most of the plants do not have the bigger problem with the low temperatures, but rather more with the high humidity that prevails in Central Europe during the winter months.
At the habitat of some Opuntia, Gymnocalycium, Echinocereus and Escobaria the night temperatures can drop down to -40°C (-40°F). The key to cultivate these plants the year-round outside without damaging them is a good drainage in the pots, boxes or the outdoor bed.
For this you can used coarse gravel or crushed stone which ensure a fast drain of water after rain or melting snow. The drainage layer must be at least 10 cm (3.94 in) thick and should be covered with a nonwoven material. This is neccessary because:
1. to prevent overgrown with weeds and
2. that the plant substrate does not fill the required cavities of the drainage layer.

Then you fill the bed with a 10 cm (3.94 in) thick layer of the actual planting substrate which contains a lot of mineral components, such as broken bricks, broken lava or coarse gravel. In addition a little or non humus should be included but also a little clay.
On the plant substrate you put on a 2 cm (0.79 in) thick layer of coarse particles, such as gravel with a grain size up to 1 cm (0.39 in). This causes a rapid drain of water and keep the neck of the root dry, which can easily rot in standing wet.
If you want to build a outdoor bed it is best to chose a place which has a southern exposur and a slight slope from 20 up to 30° which can easily achieved through a landfill. Large stones will be set on the first drainge layer which not only improve the appearance but also contribute the microclimate positively. During the day these stones store the heat from the sunshine which they emit slowly in the night. You can also set some plants in the clefts with the result that these plants are once again protected against cold winds.
It is also good if the bed is placed against an existing wall. It can also store heat and serves as a protection against the cold wind. An existing roof edge can also protect the bed against some heavy rain falls.

 

 

 

How survive cold-hardy cacti the winter?

Some of the cold-hardy species can survive the winter, but not entirely unprotected. Therefore, it is necessary to establish a rain protection from early October until early April. This should definitely consist of translucent material. You can use e.g. corrugated polyester or glass mounted on a wodden frame. Of course the whole construction must be storm-proof.
The rain shelter should be at least placed 0.5 m (19.69 in) above the plants and should also be open to all sides to allow that the plants get fresh air. This is necessary so that the plants can dry fast after they got a bit wet from a rain shower or from snow.
Snow which was blown under the roof must not be removed, as this also protects the plants and prevents the dangerous frosts on clear nights. You can also carefully cover the plants with light snow if some strong frosts are forecasted.
In the natural habitat, the plants are often covered with snow for months and do not come out until the snow melts in spring.

 
     
 

 

 

What care do cold-hardy cacti need?

The ongoing care is limited to pluck a few weeds, that's almost everything. You should only water in exceptional cases when it has not rained for several weeks. Then you can give some water in intervals of 10 to 15 days. A fertilization done twice a year is quite sufficient for the supply of nutrients. The most appropriate time to fertilize is between May and June. From August on the plants are slowing down their growth at that time it is appropriate to do a slight potash fertilization. This causes a maturation of the new drives reduces the cold sensitivity and has a positive effect on bud formation.

 

 

Recommendable cold-hardy cacti

The following list is just a small selection of cold-hardy cacti which are easy to cultivate. A lot of other cacti species and hybrids are offered in special nurseries. Not forgetting the many winter-hardy succulents which valorize a well constructed outdor bed with their beautiful blooms.

Corynopuntia clavata

Cylindropuntia imbricata
Cylindropuntia kleiniae
Cylindropuntia whipplei

Echinocereus adustus
Echinocereus albispinus
Echinocereus baileyi
Echinocereus caespitosus
Echinocereus caespitosus var. minor
Echinocereus chloranthus
Echinocereus coccineus
Echinocereus coccineus ssp. rosei
Echinocereus davisii
Echinocereus fendleri var. kuenzleri
Echinocereus mojavensis
Echinocereus oklahomensis
Echinocereus reichenbachii
Echinocereus reichenbachii var. albispinus
Echinocereus reichenbachii ssp. baileyi
Echinocereus reichenbachii ssp. perbellus
Echinocereus triglochidiatus
Echinocereus viridiflorus

Escobaria leei
Escobaria missouriensis
Escobaria missouriensis var. caespitosa
Escobaria sneedii
Escobaria vivipara

Opuntia aurea
Opuntia basilaris
Opuntia fragilis
Opuntia fragilis 'Feldberg'
Opuntia fragilis 'Freiberg'
Opuntia fragilis var. denudata 'Prag'
Opuntia howeyi
Opuntia humifusa
Opuntia phaeacantha
Opuntia polyacantha
Opuntia polyacantha var. hystricina 'Hamm'
Opuntia polyacantha var. hystricina 'Muenchen'
Opuntia rutila

 

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