Botanical Name — Dolichothele longimamma
Common Name — finger cactus
Plant Family — Cactaceae
Dolichothele longimamma are small, low-growing cacti, that form fleshy, fingerlike tubercles and produce many offsets. Unlike many cacti, they grow from a large taproot that reaches deep into the soil and stores plenty of water. They are native to central Mexico where they can be found growing on limestone or in volcanic soils in areas of sparse vegetation. Though fairly common in cultivation they are rare across their native range due to unsustainable harvesting practices.
- These cacti prefer lots of sun, at least five hours of direct sun daily.
- Indoors a south facing window is ideal. Outdoors place them in a spot where they will get plenty of sun exposure, but provide them with light shade to protect them from intense, peak afternoon sun.
- Dolichothele longimamma do best in high temperatures and low humidity. Ideal temperatures are above 70 ºF. These plants should be brought indoors when nighttime temperatures fall below 50 ºF.
- Dolichothele longimamma prefer to stay on the dry side. In the summer water them only when the soil has dried out entirely. Always err on the side of under watering. They are built to withstand drought, and overwatering is one of the quickest ways to kill them.
- During the winter water very infrequently, if at all. It’s safe to cut back on watering entirely. This will encourage flowering during the spring!
- These plants require a gritty, sharply draining soil mix. Amend regular potting soil with sand or fine pumice up to 50% to improve drainage and soil texture.
- These plants have thick tap roots which store a good amount of water, be careful not to water as these plants are sensitive to root rot.
- These plants produce lemon yellow flowers, about 2.5” in diameter, a relatively large flower for the genus.
- Flowers blossom abundantly in the summertime. A true drought during the winter will increase the likelihood of blooms during the summer.
- These plants do not require fertilization. During the spring and summer time they can be fed monthly with a fertilizer formulated for cacti and succulents to give plants a boost of nutrients and increase the possibility of blooms.
- These can be reliably propagated by offsets or by seed. Individual tubercles can also be removed from the plant, allowed to dry and then planted.
- These plants are not especially susceptible to pests or diseases. Keep an eye out for pests that commonly affect houseplants, such as scale and mealybugs. Also look out for any unusual spotting that may be a sign of an infection.
- Treat infested plants with diluted neem oil. If plants are infected with a bacterial or fungal disease, prune away any affected parts of the plant.
Maintenance (pruning, legginess, repotting)
- Very little maintenance is required to keep these plants happy. Repotting should only need to be done once every two to three years. Repot plants in a container that is two to three inches wider in diameter and be sure the pot has enough depth to accommodate the large tap root.
- This plant is not reported to be toxic, still, to be safe, it is a good idea to keep out of reach of pets and children.