Cacti are succulent plants that store water in their thick leaves or stems. While many varieties of cacti grow to massive sizes in their outdoor environments, some smaller varieties are especially suitable for growing in the confines of outdoor gardens or indoors as houseplants. These miniature cacti have unique requirements and need special care to grow and thrive.
Miniature cacti are generally slow-growing plants. Members of the genus Ferocactus are desert cacti, while members of the genus Oeocereus originate in the high altitudes of the Andes. Most types of miniature houseplant cacti are desert dwellers that require arid conditions. Button cactus (Epithelantha unguispina) and rainbow cactus (Echinocereus rigidissimus) are two varieties of miniature cacti that grow natively in the deserts of the United States as well as areas of Mexico. These plants reproduce by blossom and seed formation.
Miniature cactus plants require porous soil with good drainage. Mixing equal parts of compost, sand and grit provides a suitable medium for miniature cacti pots and gardens. Use horticultural grade sand rather than common fill sand that may contain excessive amounts of salt. Prepackaged potting soil is suitable for the compost material, as long as it doesn't contain a heavy ratio of peat moss. Perlite, pumice and porous gravel are types of grit, the large particles in cacti potting soil that ensure good drainage.
Miniature cacti prefer dry soils to moist ones. Continual moisture can lead to fungal conditions and rot in these plants. In their native environment, miniature cactus plants often withstand long periods of drought. Miniature cacti require less frequent watering in the winter than in the spring and summer. During the active growing season, water your miniature cacti deeply, allowing the soil to dry out between waterings. During the winter, wait for the cacti to show signs of dryness, such as slight shriveling near the stems, before you provide additional water.
Although they are small, miniature cacti do not grow as understory plants. These little cactus plants require full amounts of sunlight. Place potted houseplants near southern windows that supply a majority of daytime sunlight. As outdoor garden plants, miniature cacti thrive in open areas of the landscape that allow abundant amounts of full sunlight and airflow.