I have heard various opinions on how sunshine affects Sempervivum coloration. I'm not too sure so I thought we could crowdsource this. I don't need facts or evidence, just your opinions based on your experience. It seems to me that semps are healthy with a half day of sun or a full day in a reasonably semp-friendly climate. (Sorry, Southerners)

But which is better for color?
Or is there no difference?
Is it different between Sempervivum vs. Heuffelii?
Is it different between color schemes? (reds vs yellows vs purples vs greens)
Or is it different based on individual cultivar?

My own unfounded opinion that more sunshine is better, but I don't really know.

Here is 'Michaels Golden' not looking very golden. But it is November and he is actually a very lovely bright, jade color. But I wonder if moving him to the sunnier part of my semp garden will bring out his golden potential next season. Maybe I'll just move some of his offsets and compare them next summer.

My experience is that the most vivid colors come out on 'Michael's Golden' when in full sun. That being said, this one suffers from full sun in the drought season here in the Pacific Northwest.
Here it is in full sun in October of 2014. I would take a new photo today, but I recently moved them to a bed with some morning shade and they aren't to happy looking with all this rain.


I do feel that full sun brings on more intense colors in almost all of the semps. Then there are semps that seem to show more extreme coloring when stressed by heavy spring rains. Like this heuff.


Spring and early summer does seem to bring on the color show in many of the semps.
May


June This one is blessed with great color year round.


June and October


There are so many variable between the hybrids. Some have the best color in spring, some in summer, and then there are those with great color changes throughout the seasons.
But I do believe that day length, temperatures and exposure to sun affect how well each cultivar will color up.

I wouldn't be too surprised if extended sunshine would help the colors. But I kinda figured heavy rains or lots of water would make them dull. I'm glad to hear that's not necessarily the case.
I seem to recall Greg being a fan of less sun, what say you Greg?

I've found that it can depend on the cultivar. If I'm not happy with the performance of a plant I'll try another location with different amounts of sun and see what happens. But there are other factors too. I did an experiment with 'Plastic' one year. I grew it in the ground and also in a container right next to each other for a year. Here is the result - same plant, same sun, amount of moisture, etc. I thought the results were pretty interesting!

Wow, that is a really dramatic difference Chris.

Chris, your results seem to indicate that we simply can't make very good predictions. That's both annoying and interesting at the same time. I wonder what those 'Plastic's would have done if they were both in only half sun.
Those potted 'Plastic's would have had alot more root zone temperature fluctuation, and confinement. I sometimes think that a mildly stressed semp will color up better. By the same token maybe Lynn's Summer water restriction would yield different results than my garden which gets moisture year round... maybe too much.

Wow Chris that is really cool!!
Tim my answer isn't an easy one...I think there is a balance between how much sun for the different types of semps. (some like more some like less)
I don't have a pic but my Michael's Golden is a different color from yours and mine was in full sun, so I'm thinking specifically that one - sun makes a difference to coloration. I found a couple heuf. Feuerrad that were up against the side of my trough (in the shade line) and they were a different color from the others in more sun. For me my best result is morning sun, afternoon shade, and in full summer heat shading a bit more as needed. This year I didn't do that and several were crispy, don't even know if they are going to make it...but the ones with shade are all doing great. Stress does get them to color up (again my experience) and I think the stress of crowding helps with odd behavior (monstrose, or cresting) but these could be totally coincidental, and these plants would have done the same thing without my having crowded them? Since I often don't have a good 'control' to compare with, then it seems like guess work, but it does make me think certain things about how to get what we want from our semps.

I knew it was a long-shot when I started this thread. That a simple answer could be given is a fantasy. It's clearly a multi-variant situation with confounding factors... I know I'm confounded. I'll try to keep my eyes peeled and see if I can spot any trends. I'm also kind of interested in soil mineral content. I think I may experiment with Calcium, Magnesium and Phosphorous. Maybe some seaweed meal which contains many trace minerals. Who knows what might turn up.

Remember that you are probably already giving them far more nutrients than they'd get in situ.
But seaweed sounds gentle enough Also I have found that there seems to be a reaction when they aren't getting enough sun - they turn green pretty quickly. (or if like what you describe, they show less color) AND winter sun compared to summer sun is another thing to consider - winter sun being far more gentle on the plants

Soil minerals I now think is a more interesting topic. Most of us have more control over that than sunshine anyway. I've read many of the sempervivum-list.de descriptions by some of the big names over there and often it was mentioned that color was dependent on soil mineral content. No details provided of course.
Native soils in alpine (or desert) situations are quite "young" soils that have not been leached by rains for centuries like down here in the valleys. So mineral content may be more robust. Ph would also be slightly above neutral instead of below neutral like down here in the rain forests. That's why I've added a bit of Ca where I grow any succulents. I think it would be interesting to try some Ph experiments... why not. I think it may be time to break out that 50-pound bag of dolomite lime in my garden shed.

I was telling Kevin that I topped dressed with a mix of chick grit and lime chips. Seems like his reply was semos don't like lime. I could be wrong!🤔

Whatever you do I'd go very lightly since even in the mountain soils, it is usually a thin layer.
Curious to see if there is any amazing result

The answer is COMPLICATED!

Almost everything affects anthocyanin production: light, temperature, stress, pH, minerals, and moisture. So, not surprisingly the colors are all over the place and also why semps vary in color so during the season.

Right now I'm trying to select for those that keep at least some color year round. Killer for example never looks the same but always has some color phase. It is a red/ green bicolor right now. When I started growing semps, NONE of the semps retained their color in the summer. This has all come about through our breeding. Jungle Shadows was the first that did it for me and it passes this trait along to its progeny. Right now I have some huge purples that retain their color year round.

A study by a European showed that the soil in cavities where semps grow is ~pH 4.5, something that would grow good blueberries or cranberries! I never add lime to the soil although some are in beds bordering bearded irises which are limed. The all-semp beds are never limed. My soil is ~6-6.5. You can tell this yard was once solidly in Douglas firs.

Kevin

Yeah... I gather the answer is simply too complicated to even worry about. Just give them your native soil and that's as good as anything else we can figure.

A Ph of 4.5... that doesn't seem natural. I wonder if that's a condition created by semps to discourage roots of other plants.

On the other hand... I do wonder what are the optimal conditions for Sempervivums. I often think the mountain crevices are not optimal but rather survivable habitat for them. A place not survivable for most other plants. Would they actually flourish much better down in the valleys if not for the many aggressive shrubs, trees and weeds that would choke them out? Plants that cannot survive in those alpine environments. Do we not feed them Nitrogen although there would be precious little in a rocky crevice. They seem to like that. Maybe they would love some more Ca in my naturally Ca-deficient soil. I seriously doubt it would bother them even if it was needless. I would think the weathering rocks in an alpine environment would provide a good deal of Ca. So much I don't know.

Tim,

Yes I was surprised with the study too. When you think of those crevices though it is most degraded leaves and other organic matter trapped in the crevices. I had them planted in similar crevices in the huge banded gneiss boulders on my parents' property in MA. They looked great in it. Most of the "soil" was degraded pine needles and oak leaves so I'm sure it was very acidic too.

You are also right that semps grow in the wild where other plants don't. They couldn't compete with grasses but they can in a crevice in the rocks. They LOOK much better given good garden conditions. The Swiss horticulturist Correvon sort of rejected this lush growth as "unnatural" and grew some of his plants in austere conditions. In my opinion, you wouldn't starve your other plants, so why semps? I want mine to be HAPPY.

Kevin

I've been giving a lot of thought recently as to how to balance nutritional requirements as clumps become crowded. Kind of tricky when space is limited.

In my part of the world, they go pretty dormant by this time of year (November) and will soon be blanketed with 3' or more of snow until March/April.

I've noticed more this season as we've not had the sort of November snow we usually get. They look almost ratty right now and smaller than I would expect. I'm assuming this is partly because they are sort of dormant - waiting for snow cover and then sleeping until Spring when their leaves will swell and begin to color up.

Or is the size determined by how crowded some of them have become?