Growing Cereus (Cuddly Cactus)

Latin Name Pronunciation: see' ree-us  

Cereus is a large genus of generally fast-growing, night-blooming cacti with columnar stems, from dry portions of South America. Species grown as houseplants thrive in dry heated interiors, require very little water and little more than copious sunshine.

Light: Cereus plants require very bright light and may benefit from supplemental grow lights if natural light is insufficient. Some hours of direct sunlight, such as that from an unobstructed south or west window, is ideal, as is placement in a sunroom or greenhouse. Lack of new growth or pale, weak growth indicates the need for more light; summering outdoors protected from heavy rains is beneficial.

Watering: Very low water needs for these plants. Let soil dry out completely before watering. Tissues will become wrinkled if water is insufficient, mushy if too wet. Overwatering is likely to cause root rot and death of the plant.

Temperature: Warm household temperatures are suitable for these heat-tolerant plants. A cool (50-60° F), dry rest period in winter is beneficial.

Soil/Fertilizer: Repot and freshen soil with a very well-drained potting mix or Cactus formulation every few years, upsizing the container as necessary. Cereus requires very little fertilizer. You may fertilize with a balanced houseplant formulation at ¼ -½ strength, no more than monthly during periods of active growth.

Humidity: These plants, being from an arid climate, thrive in low humidity. Do not mist or add humidity.

Pests/Diseases: Fuzzy white “wool” that protects emerging growth naturally forms around the areoles. It is best to leave it in place. Mealybugs can be distinguished from this natural fuzzy growth by their irregular appearance, sticky residue, and random occurrence around areoles or between ribs of the plant. They are easily removed with a cotton swab dipped in alcohol.