Ortegocactus macdougallii is a slow-growing clumping cactus that grows in a very limited area in Mexico (Oaxaca). It grows at a height of 1600-2000m on rocky limestone areas where little else survives.
They can display either black or white spines and have yellow funnel shaped flowers.
I cultivate mine in an 85-90% mineral soil with bonsai rock chips, quartz pebbles, broken bricks and some pumice all sieved out to a size of between 2 and 6mm. To this I add 10-15% of home made compost.
I water very sparingly through summer but also occasionally mist spray the plants.
Based on the general advice of adding limestone to the mix, I did so on a previous specimen and it promptly died. Now with any species from North America I avoid limestone like the plague. They are very sensitive to overwatering when in a less than ideal well drained soil. Also they can be susceptible to attack by mealy bugs so regular checking is essential, and treat appropriately if an outbreak is found.
Willy Verheulpen
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