Just keep it in dapples sun then...no need to have stretched succulents in your climate :) - I have, but winter is too long and too dark for succulents and even supplemental lights are not as good as real thing. They are native to Mexico, am sure closer to your climate than mine. Here is one of mine, in January, under the lights:

They are reaching for more light. To keep these guys compact they need a good amount of sun. If these were mine I would start all over by cutting off the top. Let callous for a day or two and then replant. If you can they would do better outside. Before you put in sun or water make sure they have roots and introduce them to the sun slowly. They may burn if not ready. Lastly, take some leaves off to propagate. Goodluck:)

Plants are kept, very often, in poor conditions in the stores. They suffer most 'abuse' even if not intentional. Some conditions could and should be changed immediately (like a potting mix, proper container and so on), some may take time - like light exposure (best to go slowly). I hope Kevin or someone else with lithops will chime in - I would be tempted to burry them deeper upon repotting - obviously, well draining mix is very important. Potting them or any other succulent, deep in dense & water retaining soil wouldn't be a good idea. I don't remember reading anywhere how soon to burry them - maybe that info is somewhere. I copied one of the posts by hanzrobo while he was posting, below is that thread with good photos: hanzrobo(11) Also, you could afford to put a little more soil in there, bury them a bit more. They're about twice as tall as they should be at their leggiest. More light will help. Try adding an extra hour of light if you can. http://forums.gardenweb.com/discussions/1799852/lithops?n=14 Here is one of the posts almost year ago where Kevin posted many good links: ewwmayo(ON-CA 6a) Minty - I haven't really been keeping track, but perhaps here are a few helpful online reads: Llifle - Photos for Identification Llifle - Care and Info Cactiguide - Growing Mesembs by C&C (very useful with photos and discussion) Flowering Stones - Extremely detailed IDs, if you can handle the massive qty. Flowering Stones - Cultivation Art of Growing Mesembs - must read with a lot of insight Lithops Info - Cultivation, I like the little sketches Cono's Paradise - short but helpful Terry Smale - Growing Lithops Blog of a Plant Whisperer - Lithops facts and trivia A lot of the information is repeated and regurgitated across so many sites... after a while it's pretty obvious when the articles are by someone who really doesn't grow Lithops (or grow them well). Also spent a lot of time digging (all posts) through the Gardenweb cacti forum back to 2010? I found that all the tidbits of information are really helpful, just initially it was very difficult to figure out what's valuable/helpful or just will not apply to me ever. For the longest time I never even thought I would grow Lithops!

Dark spots are not water spots, they are sunburn. Water spots are more 'whitish/milky' color. Burn happens when you expose plant to too much sunlight suddenly, and yes - some are more sensitive to it than others. There should also be whitish powdery coating on leaves that protects them little from sunburn. But it is important to acclimatize plants. It would have been, probably, enough to turn the pot so other plants cast bit of shade on this one. It could be moved/turned bit every couple of days until plant is in full sun. Maybe Sun in Colorado is very strong? Acclimatizing would be even more important. And how good were roots when you transplanted it? Maybe not that strong. Almost all my succulents get sunshine from sunrise till sundown, but they have been outside since early May, when sun isn't as strong (at least in my zone/location).