Mammillaria SP Grafted Large white also known as Pachycereus schottii

also known as Pachycereus schottii monstrosus

But it can tolerate temperatures down to 5° C (or even 0° C) for very short periods if very dry and ventilated

If your space does not get enough sunlight

Be sure to water your Opuntia ficus-indica thoroughly before applying the fertilizer to avoid any potential root burn

Mammillaria SP Grafted Large white also known as Pachycereus schottiiThis is a really nice grafted mammillaria measuring around 6 to 7 incheas long is sold grafted onto stem of Hylocereus. It needs a well draining potting mix. Water thoroughly and let the soil dry at least halfway down the pot before watering again. In winter, decrease or withhold water. Some of the information in this description has been found at desert tropicals. com, llifle. com and cactus art. biz