Originally native to South America, we primarily use it as an attractive houseplant that can develop into a magnificent tall plant over the years. Even if the columnar cactus by far does not reach the stately height of up to 15 m as in the great outdoors of its home. Column cacti are succulent plants that can store water over a longer period of time and are therefore able to withstand longer periods of drought.

The species.

The aesthetic plants come in many different varieties, but not all of them are cultivated in our native latitudes. The best known that are offered in stores include:

  • Cereus jamacaru – single-stemmed columnar cactus with a bluish green appearance, which has narrow, deep incisions between the strong, pronounced six to ten ribs. On the hairy side shoots (areoles) it has numerous yellow-brown thorns that reach a length of 1 to 2 cm. In large and older specimens, long flowers of 20 to 30 cm form with beautiful white bracts that shimmer green.
  • Cereus peruvianus – can easily be confused with the C. jamacaru in appearance but this columnar cactus has only 5 to 8 blunt ribs and has 7 to 8 brownish thorns and 15 cm long flowers that are white on the inside and red on the outside.
  • Cephalocereus senilis – this shallow root is a night bloomer, but it rarely blooms and reaches a height of 12 to 15 cm. As a special feature, the plant has bristle hairs up to 12 cm long, which hang down twisted in white.
  • Cleistocactus strausii – is also known under the German name Silberkerze because of its soft, silver-gray bristles, which extend representatively over the green trunk. When the columnar cactus has reached a height of approx. 30 to 60 cm, it develops bright wine-red flowers in late spring.
  • Cereus peruvianus – Monstrosus variety – also known as rock cactus, is a particularly popular specimen among cactus lovers, and is characterized by an irregular and gnarled shape, which is created by numerous vegetation points. Compared to conventional column cacti, this species grows much more slowly and tends to rot if there is poor drainage.

The optimal location

The columnar cactus is located in its country of origin in dry, hot areas, so it should also be given a suitable location as a houseplant.

  • full sunlight
  • preferably on the south window
  • in the cold frame or in the greenhouse
  • alternatively in a sunny place outdoors during the warm season
  • but then with appropriate rain protection
  • on the balcony or terrace with lots of fresh air
  • Stronger, longer spines and a more intense color soon appear
  • During the low-light winter months, the columnar cactus must be allowed to rest
  • at cool temperatures
Tip: So that the plant does not grow unilaterally towards the sun, the columnar cactus should be turned at the window every now and then.

Caring for the cacti

In order for the plants to develop well and, depending on the species, to form magnificent flowers, a few essential aspects must be observed when caring for them.
The substrate

Normal potting soil, which is available in stores, is generally not suitable for columnar cacti because a loose, permeable substrate is required to avoid waterlogging. A standard mixture should consist of the following components:

  • a quarter of quartz sand, a quarter of high-quality peat-free potting soil and two quarters of fine-pored, water-storing material such as seramis, pumice, leca 2-4 or lava
  • alternatively, there can also be a mixture of coconut substrate, such as coco-hum and garden soil, which is mixed with sand
  • For sufficient water permeability, however, the proportion of garden soil must not be more than two thirds

Pour carefully

The growth phase of the succulent plant begins from the beginning of May or even earlier when the temperatures rise to over 15 degrees. Now the columnar cacti are poured extensively but evenly. It should be noted, however, that the surface of the soil can dry to a depth of about 2 cm between the individual waterings.

  • It is poured in the morning and in the evening but not in the blazing midday sun
  • with well-tempered irrigation water
  • Spraying with water is now also recommended

If the temperatures rise to over 35 degrees during the day, the columnar cactus will temporarily stop growing. Then the plant should be watered less and the substrate should dry out almost completely before watering again. At the end of the vegetation phase in autumn (September) the cactus receives less water, so that the soil of the plant can dry properly before the winter dormancy.

Tip: Every now and then, columnar cacti can shrink a lot during hibernation, but this is a completely normal process and should not encourage watering.

Fertilize

It is only fertilized twice a month during the main growing season with a special cactus fertilizer that contains a little lime and a lot of potash and phosphorus. Ordinary plant fertilizers should not be used as they contain nitrates and an excessively high nitrogen content which can damage cacti.

This is how the plant winters properly

  • cool location so that the natural resting phase can be observed
  • at temperatures of 8 to 10 degrees
  • If the plant winters in a very cold room, fertilizer and water are not used

Once the columnar cactus has found its place above the heater on a window sill, it can be given a little water once a month.

The increase

The plant can be easily and simply propagated by cuttings in spring or summer. To do this, proceed as follows:

  • Cut off the shoot with a sharp knife
  • Let the cutting edge dry off for a couple of weeks to avoid rot
  • During this time, place the cutting upright in a glass or vessel
  • Once the interface has dried, the cutting is placed in a pot filled with cactus soil
  • the soil is only kept slightly moist in order to avoid rot

sowing

Another variant of the propagation is sowing by seeds, which however requires a little patience.
Since the seed of the columnar cactus has to go through a long growing season, sowing takes place in February. In addition, by autumn the young plants will have developed so far that they can hibernate well like all other cacti.

  • Put coarsely sifted cactus soil in a seed bowl and sprinkle the seeds on top
  • but do not cover with soil as cacti are light germs
  • carefully damming up water from below
  • and cover with a clear cover
  • place warm and bright at temperatures between 25 to 30 degrees
  • the substrate must not dry out until germination
  • Impression takes place after 1 to 6 weeks
  • Then ventilate the bowl regularly
  • and keep the substrate moist
  • when the seedlings have reached 5 mm, they are pricked out and repotted in a planter at larger intervals
  • Do not cover the still young plants anymore
  • and water a little more during the transition phase of 3 months
  • then treat like all cacti

Cutting the columnar cacti

As a fast-growing desert cactus, the plant can reach a height of around 1 m and become up to 20 cm wide in a period of 6 to 7 years. Even if this imposing plant forms a wonderful contrast to the other indoor plants, the size can still be perceived as annoying. Therefore, the columnar cactus should be shortened at the latest when it has reached room height:

  • Saw off the desired area with a hacksa
  • Place the cuttings in a light place to dry for a month
  • then plant in cactus soil
  • and water it for the first time after 10 days
  • within a few weeks it will then form new roots
  • and starts to grow

The right repotting

This type of cactus is only repotted in spring or summer, when the diameter of the pot is no longer in reasonable proportion to the size of the plant.

  • Carefully remove the cactus from the pot
  • Detach dead roots and loose substrate from the root ball
  • then pot in a larger container at the same height as before
  • Top up with fresh substrate
  • So that any root injuries can heal, do not water for a week
  • the cactus does not receive any fertilization in the first year
Tip: When repotting columnar cacti, it is advisable to always wear leather gloves to avoid stings through the thorns. With a larger copy, it is worth using towels.

The optimal planter

Plastic pots are preferred for columnar cacti, as clay pots can lose moisture on the wall of the pot due to the porous material. Since roots always follow the moisture, they will then form a dense network of roots along the wall of the vessel, while there are no more fiber roots inside the pot, so that rapid water absorption is prevented.

Pests and diseases of the columnar cactus

Harmful insects
3 types of pests in particular repeatedly attack cacti:

  • Dust bunnies, which are 1 to 3 mm large insects, which are noticeable in the root neck and apex area of ​​the plant with their woolly web.
  • Root lice that are around 1 mm in size and form small, white webs in the entire root area, which means that they are often only noticeable when repotting.
  • Spider mites, which at 0.5 mm are very small but also very dangerous because they spread quickly, especially in dry heat, and can only be recognized by the damage caused to the cactus.

These 3 pests suck out the sap so that the cacti are weakened. Therefore, they should be consistently combated with:

  • a sufficient supply of nutrients with potassium and phosphorus
  • lots of fresh air
  • a close observation
  • because if the cactus shows an unusual discoloration, pests may be the cause
  • preventive pest control
  • as well as effective control immediately after the infestation

The following are suitable as control agents:

  • systemic agents such as Metasystox and Rogor
  • which is sprayed on the columnar cactus
  • but is also added to the irrigation water at the same time
  • as a preventive measure from mid-May and early September
  • after 10 to 14 days renewed treatment, however, with a different active ingredient
  • because insect pests have a short generation line
Tip: Biological preparations are not suitable for these pests, especially for spider mites.

Other possible pests are:
nematodes, scale insects and woodlice, although they are of subordinate importance in cacti, while snails can sometimes cause massive damage but can be successfully eliminated with slug pellets.

Diseases

Column cacti are not only attacked by insects and pests, but sometimes also by fungi due to incorrect care, too little light, incorrect fertilization or irrigation. These then often cause the plant to rot from the inside out, which means that the infestation can only be noticed quite late.

If the cactus is affected by fungal infestation, it has a diverse appearance because it can:

  • lose all roots
  • dry out from the inside
  • rot from the root neck upwards
  • rot from the crown down
  • or the cactus dissolves into slime from within
  • and can also be partially covered with mold lawn

A fungal attack can also be prevented through preventive measures:

  • sufficient light
  • lots of fresh air
  • an adequate supply of nutrients with phosphorus and potassium
  • avoiding injuries, especially when repotting in the root area
  • as well as sterile work during propagation and sowing can be prevented
Tip: If column cacti are infested with fungi, they should be completely destroyed with the planter and substrate.

Other diseases
The plants are sometimes attacked by bacteria or viruses, which can be seen as scabbed areas, reddish sunken spots or black spots. In this case, no measures help, only the disposal of the plant with substrate and pot.

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