Common plant as a light meter ?

Portage, WI(Zone 5a)

Miners used to take Parakeets into the mines with them. I have read recently that frogs are being considered as a gauge of the health of an eco system. An indicator species. Since most beginners in the C&S world cannot recognize etioaltion when they see it, and since most beginners have no real idea of what their plant is supposed to look like - I am wondering if there is a common ( by that I mean - easy to get and inexpensive) C or S plant that might serve as an indicator of the amount of light it is getting? A gauge. In the "tropical" plant world I might say Split Leaf Philo. Heart shaped when young or in the dark. Splits given better light. Holes and splits are ideal. OK, it may take a while for the poor plant to show us how it is doing, but still, a guage. First C&S that came to my mind was an Aloe Walmsley's Bronze. (light green vs dark green vs red, variegated, etc.) Any suggestions appreciated. A plant we can tell all beginners to get. I'm thinking light level is critical for C&S success.

Baja California, Mexico(Zone 11)

I'm interested to hear what people have to say on this. My problem is always too much light (none of my succulents live in the shade). That's entirely by choice. There is no etiolation here.

Your basic aloe vera looks pretty distinctly etiolated in low light, and that's a beginner plant at the lowest cost level. There are some seriously etiolated plants in the Plant Files picture set. Jade is another common one that you could calibrate by internode distance or color.

Lots of purple or reddish Aeoniums go distinctly green in lower light. The threshhold depends on the plant but it's a pretty good indicator of light level. And barring climate challenges, Aeoniums are easy to grow. Another good color changer (and easy plant) is Echeveria agavoides, especially the red-edged varieties.

Menasha, WI

What about rebutias? This cacti is easy to grow and quickly shows elongated growth at lower light levels.

Cannelton, IN(Zone 6b)

What about the SEMPERVIVUMS? Some of them seem to change colors with every season. I don't know if it is just the light, but maybe the temperature (or both) that changes them. I do have the Aloe Walmsley's Bronze and it turns green rather quickly when brought in for the winter.
I also use an Opuntia as a water meter. When it bends about 20 or 30 degrees, then I know to water certain plants.

Portage, WI(Zone 5a)

Cactusloverlady - I'm trying to avoid appearance of growth since many cannot recognize such. Color change would be nice.

Baja California, Mexico(Zone 11)

Lots of aloes change color depending on light level (eg. dorotheae, cameronii), also various tabletop hybrids (eg. "Black Beauty", "Vito"/"Green Sand", the list is quite long there). The problem is that other factors also go into the equation (eg. season, temperature, water) and so the color change is not necessarily useful as an indicator of light per se. The purple/red Aeoniums share this problem to some degree (especially the seasonal aspect). The red-edged Echeveria agavoides not so much in my experience.

Since that Echeveria puts out pups pretty regularly, I have had a chance to experiment with them in different locations. The way I have things set up, they go through a gradual process of light accommodation. They start out as cuttings, in bright shade (dappled morning sun). Then when they show new growth, I move them to morning sun. Then when they graduate a pot size, I move them to mid-day sun. So I have had a chance to see how they change color during the process. The morning sun area gives them a good blush, the midday sun makes it darker.

Since we had a lot of hazy days this summer (nighttime fog, morning haze, afternoon burnoff), that morning sun area got very little actual sun. The Echeverias lost their blush. I know from my local weather station that the difference between a hazy day and a sunny day is about 2-fold in terms of light energy arriving per unit area. So there you go. That tells you the useful range of the plant, don't know if it was what you're looking for.

Carlsbad, CA(Zone 10b)

How about the lowly jade plant? It's easy and cheap, or often free from friends. I have as many varieties as I can find and have found that most show some different behavior in various light conditions, plus they take a lot of under-watering abuse before that effects them. I've only had one variety really show etiolation.

I've noticed over the years that the basic jade has quite a bit of different coloration depending on the light. Outside In normal sun they are medium green with a red edge. In more intense hot sun the colors deepen, and some sunburn when suddenly exposed to unexpected hot sun. I brought one pot inside to fill a hole in my houseplant area and although it's under an 8'x8' skylight it turned a much deeper green and lost its red border; but the leaves are plumper and slightly elongated, and it's very healthy looking even after no repotting for ten years.

It would be an easy plant to do light experiments with so perhaps I'll pot some up and let them have regular sun for a few months to get established and then put them in various light conditions outside and inside and take pictures.

I also agree with Baja about the Echeveria agavoides with the red edge. I have about six in the ground and they all started out with almost full sun. Then as other plants filled in the amount of light changed and is now quite varied and so is their green color, including the amount of red edging. They've continued to grow and pup in all light conditions.

Baja California, Mexico(Zone 11)

Two clones here. The larger the plant, the more light it gets. All but one of them get some sun.

Thumbnail by Baja_Costero Thumbnail by Baja_Costero Thumbnail by Baja_Costero
Portage, WI(Zone 5a)

(please excuse the bad pun) But, are we looking at just 2 shades of Grey? Either they get red tips or not?

Baja California, Mexico(Zone 11)

Yes. The set point is in a useful range, the plant is easy, the color is unambiguous. If your red-edged Echeveria has no red edges, chances are the agave growing next to it probably isn't getting enough light. As a general rule by best guestimation, anyway.

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