Pediocactus knowltonii L.D. Benson
Knowlton's Cactus, Knowlton's Miniature Cactus, Knowlton's Pincushion Cactus, Knowlton's Minute Cactus
Pediocactus bradyi var. knowltonii, Pediocactus simpsonii var. knowltonii, Toumeya knowltonii
Pediocactus knowltonii is one of the smallest cacti in the world and the smallest and rarest species in genus Pediocactus. This tiny cactus may reach up to 2.2 inches (5.5 cm) tall and up to 1.2 inches (3 cm) in diameter. An individual is considered to be an adult when it exceeds 0.4 inches (1 cm) in diameter. It is spherical or somewhat cylindrical. The areoles are round and covered in hairs. Each areole has up to 26 radial spines, which are red, pink, or white. The flower is up to 1.4 inches (3.5 cm) long and up to 1 inch (2.5 cm) in diameter, with pinkish tepals, the outer ones sporting brownish mid-stripes. The fruit is green, ripening reddish, and up to 0.2 inches (0.5 cm) long.
USDA hardiness zones 5a to 11b: from −20 °F (−28.9 °C) to 45 °F (+7.2 °C).
How to Grow and Care
Pediocactus are difficult to grow on their roots and are cultivated only by skilled and experienced cactus growers. The growing medium needs to be porous so it can drain well and dry out completely. It does best in partial shade, and it needs protection from the sun during the hottest part of the summer.
These cacti do not like high temperatures and humidity levels in greenhouses. Pediocactus should be placed in a well-ventilated position. They like "wind." Water them moderately from spring to fall and let dry out between waterings. Stop watering and allow them to go dormant for the winter months.
The flower buds stay dormant on the plant apex all winter. They will open in spring when the temperatures rise.
Learn more at How to Grow and Care for Pediocactus.
Pediocactus knowltonii is endemic to San Juan County, New Mexico, in the United States.
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