A question- about watering

[SpikyMike]

I have a little Mammillaria hernandezii. It is coming into flour. I am in UK, Hertfordshire

I am wondering if I should be giving it a little water now at all, or allow it to go into full rest period while the flower buds are forming. It is kept indoors on a very sunny south facing window. The temperature is between 20 and 25 C through the day and probably no less than 15-18C at night.

Thanks for any advice!

Mike

[Diane]

I didn't want your query unanswered, but I guess the lack of replies is because the majority of us grow our plants in greenhouses, which require a different approach to watering.
Anyway, I'll give you my thoughts (for what they're worth). Mammillaria hernandezii is a species with thick contractile roots, which, in habitat can pull the plant down into the substrate until almost invisible, and can withstand being dry for long periods. The roots are very rot-prone, and in cultivation, that means growing in a very well-drained potting mix and very cautious watering. With that in mind, I think my advice would be NOT to water, even though you are growing it indoors, as it's usually best to err on the cautious side - if in doubt, don't!
I hope you get it into flower - I have one in the greenhouse at the moment, full of buds, and hoping for enough sun to encourage them to open, but remember, however sunny your windowsill is, it can't compare to the full light of a greenhouse. Mine was last watered a month ago, and won't be watered again until next March/April.
I'm not sure how yours will fare over winter in the warm conditions of a room, as these plants usually do best with a cool winter rest, but good luck!