Ask Mr. Smarty Plants

At first glance, our thought was to give you the standard instructions for transplanting an Agave, because the Manfreda variegata (mottled tuberose) is a member of the Agave family. From a previous answer by Mr. Smarty Plants, here are those instructions:

"Agaves produce new smaller plants around their base. All you need do is remove the pups from the mother plant using a trowel or knife and put them in smaller pots with the same kind of soil mixture that your original plant has been thriving in.  If you don't know what the original is growing in, nurseries carry "cactus mix" potting soil which is grittier and more like the desert ground the plants are used to. Keep them watered, but let the soil dry a bit between waterings so they don't rot.  These pups can have very long roots that connect them to the mother plant, but you can break them off to about the same length as the height of the plant or whatever will fit in your new pot.  Even if you think you have lost too much of the root, pot it up anyway and see what happens.  Agaves are very hardy and forgiving plants!"

However, we noted that the Manfreda variegata is also considered a tuberose, so we did a little research along those lines. From this rather technical website Flora of North America, we learned that the rhizomes (underground stems) were "globose" as in fatter than the usual stem. We also found tuberose information on this Pacific Bulb Society site, saying that the tuberose was herbaceous and bulbous. Then we went to Easy To Grow Bulbs.com picture of tuberose clump, and this led us to wonder if you would do better with the transplanting of the plant if you treated it more as dividing bulbs than of cutting away a piece of the root. If you have already tried the transplanting by cutting away smaller plants around the base, and found that unsatisfactory, give the division of the roots, which are fat, a try. 

Manfreda variegata

Manfreda variegata

Manfreda variegata

Manfreda variegata