personally i leave them on if they're still green, under the assumption they're contributing to the plant as a whole. but if i had a really big plant with lots of healthy, producing canes, i might whack off a couple of the old ones if they were starting to dry out and i were repotting it. otherwise i leave th canes till they turn brown/yellow then cut them down as far as i can get. (this on non-nobile types.)
i've got one in this situation now; longest cane is about three feet, and it's happily growing another one, and well, my kitchen ain't that big. repotting it's going to be just LOVELY i'm sure.
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"Apart from the utility of binomials for standardizing reference for effective communication,
Laelia Speciosa is a tad easier to pronounce and spell than its Atzec name
chichiltictepetzacuxochitl."
--Alec Pridgeon