How to Grow and Care for a Boob Plant

The plant known as the “Boob Cactus” is scientifically named Myrtillocactus geometrizans ‘Fukurokuryuzinboku’, a cultivar from Japan. It is a monstrose form of the Blue Myrtle Cactus, which means it has an abnormal growth pattern. This mutation results in lumpy, rounded protrusions along its blue-green stems, creating the distinctive appearance that inspires its nickname.

Boob Cactus Care

Light

This cactus grows best with plenty of bright, direct sunlight to maintain its blue-green color and compact form. An ideal indoor location is a south-facing window that provides several hours of direct sun daily. While the plant tolerates direct sun, young plants are more sensitive. Intense afternoon sun, especially when magnified by glass, can cause sunburn on the plant’s surface.

Soil

The soil for this cactus must be exceptionally well-draining. Standard potting soil holds too much moisture, so a commercial cactus and succulent mix is a better base. To further enhance drainage, amend the mix with inorganic materials like perlite, pumice, or coarse sand. A 50/50 ratio of cactus soil to an inorganic amendment is a good target.

Water

Use the “soak and dry” method for watering. Thoroughly water the plant until it runs from the pot’s drainage holes, then allow the soil to dry out completely before watering again. Check for dryness by inserting a finger a few inches into the soil. During the dormant winter months, reduce watering to as little as once a month to prevent root rot.

Temperature and Humidity

This cactus thrives in temperatures between 65°F and 85°F (18°C to 29°C) with low humidity. It is not frost-tolerant, so if kept outdoors, bring it inside when temperatures drop below 50°F (10°C). Avoid misting the plant, as moisture on the stems can encourage fungal growth.

Fertilizer

During the spring and summer growing season, feed the cactus with a balanced fertilizer formulated for cacti and succulents. Dilute the fertilizer to half or quarter strength and apply it once every two to four weeks. Stop fertilizing in the fall and winter when the plant’s growth slows.

Propagating the Boob Cactus

The best way to create new plants is through stem cuttings, which preserves the unique monstrose traits. Propagation from seed is not recommended, as the resulting plants will likely revert to the standard Myrtillocactus geometrizans. This process is most successful during the active growing period in spring or summer.

Select a healthy arm or section of the main stem and use a clean, sterilized knife to make the cut. Allow the cutting to callus by leaving it in a dry, shaded, and well-ventilated area for one to two weeks. The cut surface must form a dry, hard seal, which prevents the cutting from rotting when planted.

Once callused, place the cutting about an inch deep into a pot with a dry, well-draining cactus mix. Do not water it immediately. Wait for roots to develop, which can take several weeks to a few months. Check for root formation by gently tugging on the cutting; resistance means roots have formed and you can begin a sparse watering schedule.

Common Problems and Solutions

Root rot is a common problem, with signs including a mushy, blackened base and soft, yellowing stems. Prevention is the best approach, but if rot is present, the only solution is to cut away the healthy portions of the plant. These healthy cuttings can then be propagated.

Mealybugs and scale are the most common pests. Mealybugs look like small, white, cottony masses, while scale insects are small, brown bumps on the stem. Manage them by dabbing affected areas with a cotton swab dipped in 70% isopropyl alcohol. For widespread infestations, use an insecticidal soap.

A lack of light causes etiolation, or stretching, where stems become thin, pale, and elongated. This stretched growth is permanent, altering the plant’s shape even after its health is restored. To fix the issue, move the cactus to a location with more sunlight, acclimating it gradually to prevent sunburn.

Repotting Your Boob Cactus

Repotting is needed only every two to three years or when the plant has outgrown its container. Signs of a root-bound cactus include roots growing from the drainage holes or the plant becoming top-heavy. The best time to repot is during the spring or summer growing season.

Select a new container with drainage holes that is one to two inches wider than the previous one. Handle the plant safely with thick gloves, tongs, or folded newspaper to protect your hands and the plant’s surface. Gently remove the cactus, knock away the old soil, and place it in the new pot with fresh, dry cactus mix.

After repotting, do not water the plant for about a week. This waiting period allows any bruised or broken roots to heal and form calluses. Watering too soon can introduce moisture to these wounds and cause rot.