Wait a bit before fertilizing 'Thanksgiving cactus'

Q: I have read your columns for years, including the ones on Christmas cactus, and enjoy them very much. I must have a “Thanksgiving cactus” since it seems to bloom in early November, and sometimes (again) in the new year. I have transplanted into larger pots several times. It is currently starting to bloom. The room it lives in is cool, with only indirect lighting that isn’t separately lighted at night very often. I never had to cover it with a box and probably wouldn’t go through the effort. I am wondering what type of fertilizer I should add and when? — J.S., Tijeras

A: I have done some poking around about Christmas cactus because I think the variety available now showing bloom are, if I’m correct, actually the variety known as crab cactus.

They are a smidgen different looking than the true variety Christmas cactus. The difference being the Christmas cactus segments have a smooth, scalloped edge, and the crab cactus has teeth protuberances along its segment edges, two teeth especially where the next segment grows from the one behind it.

The crab cactus is noted as coming in several color choices of blooms, too. You can find them in salmon, pink, orange and white.

Now going through life being called a “crab” would get old quick, and since they seem to bloom, usually in November, I have heard them called Thanksgiving cactus more times than not. The Christmas cactus, if triggered properly, usually blooms at Christmastime.

Also, Christmas cactus blooms are typically a rosy-purplish red color. The Christmas variety doesn’t seem to offer the myriad of bloom color choices the Thanksgiving cactus does.

All that being said, I think that your cactus is triggered naturally. You say the room it lives in is cool and the light is indirect. With the change of seasons, that indirect light has lessened, the room is cooler and voilà, the plant has sensed the time to set bloom and show off has arrived. It’s doing everything so naturally that you should be pleased.

I don’t know how often you are watering this treasure. I have learned that they come from the jungle in nature, so they are to never dry out. Think of both the Thanksgiving and the Christmas cactus as succulents. Depending on the size of the pot, the warmth of the room and whether or not the air in the home is terrifically dry, you might water every ten days or so. But yours looks good. You can stick your finger in the soil a knuckle deep, at least, and see if the soil is dry. If it is, water. If it’s soggy, then don’t.

Also know that they prefer a rich, yet porous, soil. The soil they live in best wouldn’t compact. Any good potting soil, like the brand Happy Frog, with the addition of a bit of clean sand to keep the soil from compacting and continue draining properly, would make a perfect environment for growing. From the picture you sent, I didn’t notice any calcium or salt build up on the rim of the pot, so that’s really good. I just don’t know how often you do water, but the segments look plump, not wrinkly skinny, so that’s good too.

I did want to ask if you “take the plant for walks?” I suggest a quarter to half turn of the pot every week, so the plant gets equal light. Don’t move it to a new locale, just get in the habit of turning the pot so the light absorption is more equalized. Seems like most of the blooms are more on one side of this guy than evenly distributed, so get in the habit of “taking it for a walk.”

Now for fertilization, once it’s finished blooming, wait a couple of weeks to fertilize it. Depending on when the plant was repotted you might even wait until spring to feed since the soil might still contain all the nutrients the plant needs. A liquid fertilizer, following manufacturing suggestions, will work. You want to remember to have watered the plant just before fertilizing because you NEVER fertilize dry soil or roots. Miracle-Gro makes a liquid that’s easy to find and use.

One more suggestion, I wouldn’t go up in pot size, since the Christmas and Thanksgiving cactus like to keep their roots snuggly. Too much room in the pot for the plant to have to fill with root, usually the above ground plant suffers a bit and this one looks pretty darn good.

Keep enjoying the bloom, get in the habit of taking it “for a walk” and it seems that you are on the right path to having it for a long time.

Happy Diggin’ In!

Tracey Fitzgibbon is a certified nurseryman. Send garden-related questions to Digging In, Albuquerque Journal, 7777 Jefferson St. NE, Albuquerque, N.M. 87109, or to features@abqjournal.com.