Crassula COLUMNARIS

Crassula COLUMNARIS - Khaki Button, Columnar crassula, Crassula columnaris, Crassula MITRATA.

Crassula is a large genus of succulent, herbaceous, subshrubby, and shrubby plants in the family Crassulaceae, comprising several hundred species distributed almost worldwide, but particularly diverse in South Africa. In nature, representatives of the genus are found on rocky slopes, sandy plains, quartz outcrops, in the Karoo, fynbos, dry shrub communities, seasonally moist places, and on poor, well-drained soils.

Plants of the genus vary greatly in shape: among them are miniature ground-cover species, rosette succulents, compact columnar forms, and large shrubs with woody shoots. The leaves are usually opposite, fleshy, capable of storing moisture, often tightly pressed against each other, covered with a waxy coating, dots, cilia, or a matte cuticle.

The flowers in crassulas are small, star-shaped, most often white, cream, pinkish, reddish, or yellowish, gathered in terminal inflorescences. After flowering, very fine seeds form. In many South African species, seeds germinate better during the cool season, under bright diffused light, with surface sowing and stable light moisture without wetness.

Crassula columnaris is a miniature succulent from the northwestern part of South Africa and southern Namibia, associated with arid regions, rocky and quartz plains, where the plants often camouflage among gravel and dry vegetation. In nature, this is a very compact species, adapted to bright light, sharp fluctuations in moisture, and prolonged dry periods.

The plant forms a solitary or sparsely branching short vertical column, usually 2-8 cm (0.8-3.1 in) high, rarely up to 10 cm (4 in). The leaves are very fleshy, rounded, gray-green, brownish, ochre, or reddish-brown, arranged in four dense rows and overlapping each other so closely that they almost completely conceal the stem. Thanks to this shape, the plant resembles a small turret, cone, button, or stacked column of dense leaves.

Flowering occurs in mature plants after a period of accumulating strength and is tied to seasonal conditions. From the upper part of the column appears a dense inflorescence with numerous small flowers, usually cream, yellowish, orangey, or pinkish-cream, sometimes fragrant. After flowering, part of the shoots may gradually die back, but the plant often persists through lateral shoots or self-sowing.

Seeds of Crassula columnaris are very fine, brownish, dust-like or near dust-like, easily lost during careless handling.

Sowing is preferably carried out in autumn or winter, corresponding to the natural development cycle of the plant. With artificial lighting, year-round sowing is possible. A sterile fine-grained mineral substrate is used, with a well-drained lower part and a thin top layer of washed coarse sand or fine mineral chips. Seeds are distributed over the surface, neither buried nor covered, but only lightly pressed against the moist layer.

The sowing is moistened from a spray bottle with a weak solution of potassium permanganate or biofungicide with the addition of a growth stimulant. The container is covered with a transparent lid or placed in a greenhouse. Germination is carried out under bright diffused lighting at a temperature of about 16-22 °C (61-72 °F), without direct sun or overheating. The surface is maintained slightly damp but not wet, sowings are aired regularly, and condensation is removed.

The first seedlings may appear within 7-14 days, the usual germination timeframe is about 2-4 weeks, and the maximum possible timeframe under overheating or partial surface drying can stretch up to 6-8 weeks. After seedlings appear, the cover is gradually cracked open, and seedlings are kept under bright diffused light, moderate coolness, and very careful moistening. Pricking out is performed only after noticeable strengthening of the small columns, when plants can be transferred without damage to delicate roots.

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For cultivation, a very bright spot with bright diffused light and gentle direct sun in the morning or evening is selected. In hot climates and behind glass, it is better to protect the plant from harsh midday sun, especially after repotting or a dark wintering. With insufficient light, the column stretches, the leaves separate, the coloration pales, and the plant loses its compact form.

The main period of growth falls during autumn, winter, and spring, whereas in strong summer heat the plant often enters a state of relative dormancy. Growth proceeds best at a temperature of about 12-22 °C (54-72 °F) and good air movement. During hot periods, frequent watering and heavy damp soil are especially hazardous. Overwintering is kept bright, rather dry, and cool, without overheating and without constant dampness at the roots.

Watering is carried out very cautiously, in small portions, only after complete or near-complete drying of the substrate. During active growth, infrequent moderate moistening is permissible, while during hot summer dormancy and cool keeping watering is drastically reduced. Water must not linger between the tightly closed leaves and at the apex of the plant, as this quickly causes rot.

A very loose mineral substrate with a high content of quartz gravel, coarse sand, fine stone chips, pumice, zeolite, perlite, or other inert aerators is used. The organic component is added minimally, only to retain slight moisture during growth. Substantial drainage is placed at the bottom of the pot, and the container is chosen small, shallow, and necessarily with drainage holes.

Fertilizer is applied rarely, only during the period of active growth, no more than once every 8-10 weeks with a very weak solution of fertilizer for cacti and succulents with low nitrogen content. Excess nutrients cause loose growth, increase the distance between leaves, and reduce resistance to rot. Repotting is carried out at the beginning of active growth; after repotting, the plant is kept without watering for several days.