Luckily this is one variety that will take higher temps, so as long as it has enough light it should do well indoors. Even when it begins to send up flower heads it's used. Looks like a good choice.

And the plant is a wonder to behold. Here in zone 8b, in the mid of winter I can have rich green leaves on dark purple stems, with delicate bright yellow flowers. It is a grace in winter. The leaves are good in soup, salad and stirfry.

Which choy sum is being discussed here, the white stem type or the green (yu choy)? Names are confusing.

Jim