Ok...this is a family heirloom cactus...from my mothers twin sister Velma...out of the delta...I have grown it for decades myself...these were a group that were removed from the mother a few years ago...blooming together today...ok they have had the same conditions so it is understandable that they might bloom together..today...
Across town in the. Village. There is sitting on a window sill another sibling ....grown in as different a situation as possible..both summer and winter all were separated from the mother about 3-4 years ago..at different times and have been living apart ever since...
Is there a date stamp imbedded in the genes..how do they know/ remember that date

Soooo pretty!

It is nice

Completely gorgeous & awesome!

W/o knowing a thing about actual prickly cacti, the "same day" comment makes me wonder if it's a plant that is responding to day length. Some plants bloom during the shortest days of the year, some the longest, some closer to an equinox, and some are just opportunistic and toss up blooms whenever conditions don't prohibit.

Your post didn't include the name, hard to add to wish list. ;)

Love your Pelargoniums & Oxalis in the background too!

Yes, my thought was long day vs short day bloomers. Short day bloomers bloom in the fall when the night starts to lengthen. Long day bloomers bloom in the spring when the night is shortest. You can intentionally (or unintentionally) manipulate that with lights.

My grow lights are timed to sunrise and sunset so about once a month, I reset the timers. That allows my plants to bloom when they are supposed to bloom. But, if the lights were the only source of sunlight, I could change the length of my days and make my plants bloom out of season. Likewise, by having a plant that is very sensitive to long day/short day in a spot where the lights were turned on and off, it might never bloom. It's not the day length that triggers blooming cycles but rather the night length. If you turn on the lights, the plant's internal clock resets and starts counting all over again.

Echinopsis oxygona - the Easter Lily Cactus

Daisy

GordonHawk said:Is there a date stamp imbedded in the genes..how do they know/ remember that date

This is something I have observed and it is fascinating. The synchrony of certain plants can be remarkable. I think the embedding mostly has to do with pollination. If you only have one chance to make the magic happen, it really helps to agree about the date of the date. Like Daisy says it has to do with the day length and stuff like that, but this pollinator angle really explains a lot of stuff that we observe with flowers.