Botanical Name: Cactaceae family
Type: Succulent/ Cactus
Origin: Mexico, South America and Southwest USA
Height: The height a cactus can grow to depends on the particular species and varies significantly.
Soil: While special cactus potting mix is obviously the ideal solution, mixing 1 part of perlite or sharp sand with two parts of a quality all-purpose potting soil will do the trick. Adding a half inch thick pebble layer to the bottom of the pot will assist drainage and add weight to the lower end of the arrangement, as large cacti have a tendency to be top-heavy.
Light: Cacti need a minimum of two to three hours of full sun light per day.
Humidity: As a rule, a cactus will prefer dry to average air.
Temperatures: An average of around 18 to 24 degrees C (65 to 75 degrees F) will do nicely, with the cactus needing a cooler night time temperature of about 10 to 16 degrees C (50 to 60 degrees F) during the winter months.
Water: Most cacti need to be watered regularly during their growing periods, from spring through to autumn. In winter, watering should be reduced to a minimum. Under-watering will result in the plant appearing wrinkled and shrivelled (which can be easily remedied by watering lightly on successive days), while over-watering will cause its roots to rot and should subsequently be avoided.
Fertiliser: Because cacti need lower nitrogen levels than foliage plants, while needing extra amounts of potassium and phosphorous to promote strong roots and better flowering, a 2-7-7 cactus fertiliser should be used according to instructions.
Propagation: Many members of the Cactaceae family grow offsets at the base. These offsets can be cut off using a sharp knife during spring/ early summer. After allowing the cut surfaces to dry for a day or two (this prevents the sap from oozing out and causing the new plant to rot), the offsets should be placed onto the surface of a sandy, moist potting mix. They then need to be kept in a bright, warm place. For the first month, however, they should be kept out of direct sunlight.
Description and Care Tips
Comparatively easy to grow, cacti vary significantly in shape, size and flowering habits. As there are hundreds of different species, it is difficult to give detailed descriptions of any one particular species here (perhaps a special cactus encyclopaedia will be added at a later date).
Until it becomes possible to go further into different species of cacti and their individual care here, readers may find Easy Cactus and Cacti Guide will provide a wealth of useful information. There are also some great posts about cacti at House Plants Decor.
Essentially, cacti can be distinguished from other succulents by the raised or sunken spots (areoles) from which flowers and spines emerge. What is for sure is that all cacti love plenty of sunlight. Most of them will flower, although some species need to be mature to bloom, which can in some cases take years.
In spring, or when the roots have completely filled the pot, the cactus should be repotted into a pot one size larger than the original container. Choosing a pot that is too large will result in too much water being retained in the soil, causing the plant's roots to rot. Terra cotta pots are, by the way, the best solution, as this porous material will assist adequate drying of the soil.