Dear fellow cultivators,

To expand my collection of more mature Pedro's and Peyotes I started growing cacti form seed.

It started out perfectly with healthy nice looking mini cacti. Now I moved 2 months ago and that's when problems started.

Almost all of the cacti lost their color and became white (except the tip). Some of them became brown.

In my previous house it always was 22 degrees because it was a very well isolated apartment, now I moved to more rural area in an older house where temperatures drop to 15-16 at night. I don't want to heat at night because it'll be a waste of energy.

Could these night temperature drops cause this whitening? Or are there other factors where I should think about?
I didn't change watering pattern and they get about equal sunlight.
Also they stand in a transparent box on the window sill which maybe gets hotter now and then because in the apartment the heating was never on. I closely watch that they don't dry out though.

It's a bit of a bummer, but I want to start all over and any tips are appreciated.

My more mature cacti doing pretty well in the new housing but actually started to grow without giving them to much water and therefor are a little thinner in the tops now.

it is very hard to know, but it seems like it might be excessive sunlight...

when you moved, what was the story for the cacti, did they ever sit in shade for awhile?

does the window they are in face the same direction as the one the were in before?

does the container they are in face the same direction that it did before?

to much sunlight for sure.cacti that age need a screen to shade the sun.first year is crucial and you must observe closely your specimens.
get more seed and start over.

I have seedlings in sun, I sprouted them in sunlight, they face southeast right now and are totally healthy.

They can take full sun when young if they are cared for carefully, but if they are moved into it quickly doom is certain.

Thanks guys.

I didn't realize it but they indeed are south facing now instead of north so they get a lot more sun, although it's the winter sun. I thought it was the temperature. Also I didn't know that at 8 months they were still so sensitive to too much light.

It really went quick (only a couple of days for the fast damage) from nice healthy vivid green little pups to white and brown disaster. Sad but I won't give up. I had a success in sprouting them. Of 25 seeds 22 made it to this stage and were all healthy till I moved.
I have more seeds from different trichocereus species so attempt two will be taken soon.

I dont think that is absolute, as it vastly depends on the age and what kind of sun we are talking about.2 week seedlings wont last a day in a 40C direct summer sun...

at 40C (104F) maybe not, but I shave started seeds in full sun many times and had them grow great from germination on. At those temps it isn't the sun that is the issue though, it is the heat itself.

However if I did not start them in full sun and moved them to full sun they would die in hours if small and be severely burned and permanently scarred if they were older.

I have also seen them survive very hot bright conditions, but they stall in heat (mine always stopped growing when the temp climbed in summer and mostly grew in fall and spring, these plants do not like excessive heat, one of the best climates for them is the Bay Area in CA.
http://www.weather.com/w...y/monthly/graph/USCA0987

Another is Florida though they like nights slightly cooler than are often found there:
http://www.southfloridavacation.com/weather.html

In such environments they can and will thrive with full sun, once acclimated to it.

If I had climate controls I would raise them with daytime temps from 70-80 F (20-26C) and nighttime temps from 50-60 F (10-15C).