In a pot environment, sand can hold onto water. Is their rock, or perlite in your mix?. I grow my atrophytum ornatums in part shade, morning sun outdoors. It stays around 100F (38C) during the summer. I water once a week with a non nitrogen fertilizer diluted down to 1/4 normal dilution.

Here are some pictures of some of my Asrtrophytum blooms. Once they start blooming they will bloom a couple of times or more a year.

It is confusing out there on the web. Some people do not fertilize their cactus . I do find that when I do , they bloom better. I have heard that they respond to more low frequent dosed sips that a full normal concentrated dose less frequently.

Here is a link that might be useful: Astrophytum bloom shots.

I have mine in full sun. It's in gritty mix and gets fertilized with foliage pro every other week.

Laura, what is the ratio of NPP to foliagepro. Our poster lives in India, It might not be available there..

Laura lives in Massachusetts. The sun is so much friendlier up there. I have some new sun scars on my A. ornatum from leaving it in its Spring/winter spot that became an all day sun summer spot and then it reached 108 one day . Sun burn does not take long to happen (says the redheadded girl).The white speckles on the surface of the A. myriostigma will make it more tolerant of sun, but I would tread carefully . I imagine the tropical sun is harder on the cactus than New England sun. These are known to grow in shade of brush and on the east or west side of steep mountains in Eastern northern Mexico where sun is strong but gets cut off for part of the day. Sun is weird in the desert. Things hide in rocks and under overhanging lechugia. I think they get tiny bits of moving shade (bright thin shade) from brush and rocks in Nature. It LIKES sun and its warmth, but maybe not all the time not interrupted or screened slightly. Shade from brush is a very light thin shade that comes and goes..
here is a description I found. I like knowing how things grow in their habitat

"A. myriostigma is a desert scrub species and can also grow on scrubby alluvial plains (Salas de Léon et al. 1999). It prefers steep, east or west (and southwest) facing slopes between 10 and 34 degrees angle, preferably around 25 degrees, and prefers low densities. It is rarely found on northern slopes or below 1,160 m asl. This species has a 100% vertical distribution bordering the El Sarnoso mountains and prefers stony, calcareous soils (litosol-regosol calcárico) often found in thin layers in the foothills of mountain ranges. Its distribution is limited by its need for stony, calcareous or lime soils. This calcicole also needs carbonates to integrate calcium and make itself more rigid. A. myriostigma also needs well drained soils as it is sensitive to high water levels. This species is also sensitive to the cold (Romero Méndez 2006).
A. myriostigma seems to flower independently of day length, flowering asynchronously from the end of winter to the start of autumn, although they flower synchronously June-July. Temperature may be a factor limiting the northern and southern limits of distribution, since in these latitutes the east-west slopes are most exposed to the sun and these are the slopes on which A. myriostigma grows most densely. This species is found in habitat dominated by Agave lecheguilla, which acts as the main nurse plant to A. myriostigma. Nurse plants may influence the distribution of A. myriostigma (Romero Méndez 2006)."

Here is a link that might be useful: Some habitat shots.

This post was edited by wantonamara on Sat, Sep 7, 13 at 11:23

i live in so cal and my astros get full sun, all day (around 80-100 and about 10 hours). I water them varying from once a week to once a month depending on how much stuff i have to do (the biggest thing i like about cacti is not having to care about watering) I have never fertilized them, but i guess i should give that a try. they seem extremely healthy except that some are actually splitting from too much water, so i guess thats kinda bad, but otherwise good.

Thanks everybody
going with majority opinion I shifted mine to full sun and given good soaking with plain water.Propose to water it weakly till onset of winters may be after two months.As I added bonemeal and vermicompost I am not going to fertilize it anymore.
thanks once again for handhelding support.