I'm new to this forum, I recently came across it due to my new little reddish orange topped cactus, it's just like the one in the picture in this thread. I am so in love with the little thing. I know its not native to TX and I've read that I shouldn't expect it to live very long since the top can't sustain itself, however I don't want to give up on it. I don't know how to care for it or how to successfully plant the baby bulbs. Any information would be greatly appreciated.
The green bottom part (grafting stock) in the picture in the linked thread looks like a Hylocereus undatus, a semiepiphytic species that rots easily in cold weather, so don't water it when temperature is low (below 15 °C or so). It is true that these "lollipop cacti" generally are short-lived, but I am not sure about why. Anyway, you cannot plant the offsets and expect them to live since they don't have any chlorophyll and (as you wrote) are unable to sustain themselves. If you want to propagate it you must learn how to graft them, and preferably on a hardier stock than Hylocereus, such as certain Selenicereus or Echinopsis species .
Thank you, so in actuality I'm caring more for the bottom cacti than the top in order for it to survive? And how does grafting work?
Yes, the bottom part is the more sensitive of the two. How grafting works? One plant is transferred to another (similar) plant, and the vascular tissues (the transportation channels) join up. For cacti it is usually used to speed up growth or, as in this case, to help a plant that cannot carry out the photosynthesis on its own.
Thank you. Is there anything else I would need to know about the bottom one such as lighting or temperature, soil, bugs, etc.?
My experience of Hylocereus is limited as Sweden is too cold, humid and risky for them. Whenever I have got one I have cut off the scion and rooted it (if it has had chlorophyll) or regrafted it on a hardier stock. As said it is rot-prone, and I keep them in a growing medium with good drainage made of coir, pumice and similar materials. I avoid peat-based soils since peat in my experience (and many others) is bad for the roots in the long run. Bugs: the usual ones that seem to be an almost worldwide problem to cactus growers, i.e. mealy bugs and red spider mites and a few more, are a problem to this one as well. Light: They are grown in strong sunlight in Thailand and Israel (for the fruits, called "pitaya", see here for some pictures), so I think it should be able to cope with the sun in Texas, at least if gradually introduced to it (most cacti must acclimatise to ultraviolet light first, otherwise they will get sunburnt). Indoors overheating is a bigger problem, air circulation is important. I am not sure about the scion, I don't know how chorophyll-free plants react to strong sunlight. Water: As for other cacti the soil should not stay (too) wet for long periods. How much water that means depends on how the water-holding capacity of the soil and the local climate. Cacti do of course use less water than "normal" ornamental plants and I find it better to plant them in a soil that holds less water and water them more frequently. Many who grow non-succulent plants tend to grow their plants in organic matter (like peat) that can hold lots of water and then overwater them.
