Christmas cactus

Light and exposure

Unlike desert cacti, the Schlumbergera does not like full sun: as an undergrowth plant, it wants bright but filtered light. A spot near an east or north window, or set slightly back from a bright window, suits it very well. Direct summer sun reddens and burns the stems.

Light plays a key role in flowering. In autumn, it is the shortening days, combined with the cool, that trigger the buds. In our climate, the long nights of the Belgian autumn naturally do this work: you simply must not thwart the plant with artificial lighting in the evening in the room where it spends the autumn.

Watering

The Christmas cactus is not a fleshy desert plant and does not like prolonged drought, but it hates excess water. Water when the first centimetre of the substrate has dried out, roughly once a week during growth. Always empty the saucer.

The watering schedule follows the flowering. During bud formation and flowering, in autumn and winter, keep the substrate lightly moist without swings, because water stress makes the buds drop. After flowering, take a break of a few weeks by watering less, then resume normally in spring. Water at room temperature, ideally soft, is ideal.

Soil and repotting

The Schlumbergera is epiphytic: in the wild, its roots cling to bark, not to heavy soil. It therefore needs a very free-draining, airy substrate. A potting mix for cacti and succulents, or a blend of potting soil, fine bark and perlite, suits perfectly. The pot must have holes.

Repot only every three or four years, just after flowering, into a pot barely larger. This plant actually flowers better a little cramped in its pot, so there is no need to repot it too often or too large.

Temperature and humidity

In full growth, the Christmas cactus is happy between 18 and 22 degrees. But the cool plays a decisive role in autumn: to trigger the buds, it needs several weeks around 12 to 15 degrees at night, at the same time as the days shorten. Below 7 degrees it suffers, and it tolerates no frost.

This requirement fits the Belgian climate well. In autumn, a little-heated room, a frost-free veranda or a cool windowsill reproduce exactly the conditions the plant needs. The real trap is then winter in full flower: once the buds have formed, keep the plant away from scorching radiators and draughts, whose temperature swings make flowers and buds drop.

Pruning and upkeep

After flowering, in spring, you can shorten the stems to make the plant denser. Simply pinch or gently twist off one or two segments at the tip of each stem: the plant branches at that point and becomes bushier, and therefore more floriferous the following winter.

Do not throw away the segments taken off, they root very easily. Over time, remove the faded flowers and the dried or shrivelled segments at the base. That is all the care this plant needs.

Pests and diseases

The Christmas cactus is robust. Its main enemy is rot, at the base of the stems or at the roots, caused by excess water and poorly drained substrate: segments that go soft, yellow or drop, a brown and soft base. Then cut back the watering, and urgently take cuttings from the healthy segments if the base is affected.

As for pests, watch for mealybugs, small white cottony clusters between the segments, more common in winter. Remove them with cotton wool soaked in diluted methylated spirit. Bud drop, for its part, is not a disease: it almost always comes from a change of place, a temperature swing or irregular watering during flower formation.

Propagation

It is one of the simplest plants to multiply. In spring, after flowering, gently detach a section of two or three segments by twisting it at a joint. Let the cut dry for a day or two in the open air so it heals over, which prevents rot.

Then plant the section one or two centimetres deep in a free-draining, barely moist substrate. Rooting takes a few weeks. By sticking several cuttings in the same pot, you quickly obtain a well-filled plant. This is how the old family plants are passed on, often a hundred years old.

Toxicity

Not toxic to cats, dogs and children. A flowering plant you can keep safely in a home with animals, even if it is better to keep the cat from playing with the stems.

Month-by-month care calendar

Green Hub tips

• It is not a desert cactus: it comes from the Brazilian undergrowth, wants filtered light and does not like prolonged drought.
• The Belgian autumn does the work: cool nights (12 to 15 degrees) and short days without artificial light in the evening trigger the flowering.
• Once the buds have formed, do not move the plant again: temperature swings make flowers and buds drop.
• Each segment taken off in spring roots easily; this is how the old family plants are passed on.