Cactus bends over in the sun

[Marc-vdw]

Dear all!

One year ago, I was on a holiday in Naples (Italy) and saw many thin and long cactuses growing alongside houses, footpaths and stairs everywhere. I broke off two pieces to see if I could grow these into a cactus of my own, and I'm proud to say they have been doing very well. However, now that the weather has improved and they have been receiving about 3-4 hours of direct sunlight every day, I have noticed something strange happen.

Every day, after only a short period of sun, my cactus begins to bend over. Without support, it bends to an angle of nearly 45 degrees. I have checked the cactus up and down, the base feels very firm and healthy, and there are no signs of rot or insects. After a bit of sun, the cactus does feel a bit thin and less firm at the top. After some time without sun, it slowly becomes firm again to a point where it doesn't need any support to stand upright.

Now, I probably know what you're thinking, this cactus needs water. However, I have properly watered it only a few days ago when I first noticed it bending over (filling the full pot with water from below and then draining it) and the soil hasn't even fully dried up yet. On top of that, the other smaller cactuses seem absolutely fine. I have tried finding an explanation online, but the only cases I have seen of cactuses falling over were as a result of over-watering or simply growing towards the sun. Neither seems applicable here. Surely it is not too warm or too sunny??

The only thing I can think of is that I need to add fertiliser, but wanted to get your thoughts before. Thanks in advance!

PS: In the pictures, I have moved the cactus away from the light in order to take a good photo- so it's not in its actual location here.
PPS: If anyone knows what the name of this cactus is, please do share .

[teo]

Two words: etiolation and phototropism. The plant (an Opuntia, maybe ficus-indica) wants more light and stretches out in the direction of the strongest light. Also when so skinny it turns/bends easily in the direction of the light.

[Onzuka]

My first thought on I/D was Opuntia monacantha, they are popular in gardens around the Med. With more light I think it would revert to the freely offsetting habit it should have.

Steve

[Marc-vdw]

Hi guys, thanks so much for your quick replies.

However, I do not believe light could be the explanation. This cactus is placed in front of a window that faces the south-west. As such, it not only has full light the whole day (morning to late evening now that the days are longer), but it also receives a couple of hours of direct sun. When it bends over, it touches the window, that is how close it is (like I said, the photos do not show the actual location, I placed it away from the light to be able to take a better photo).

It also doesn't explain why my cactus falls over when the sun is out, and slowly becomes more firm again and able to stand upright without any support a couple of hours after sundown. On top of that, this bending over 'issue' only started happening as it was getting more sun compared to winter/early spring. And when it does bend over, it bends over all the way, so the sun doesn't shine on the top anymore, but rather the back side. It's like it needs to recover from the sun, rather than reaching for it. That is precisely what makes it such a strange case!

Perhaps also good to mention here, is that I noticed its growth has started to accelerate with the extra hours of sun it's been receiving. Could it be that it can't absorb enough water to sustain its growth and endure full sun/warmth at the same time? Notice that it hasn't properly developed its needles yet (coming out now), so it might not be fully able to protect itself?

[Marc-vdw]

Just did a quick search using the name mentioned above (thanks for that btw!) and it's suggested (here: http://davesgarden.com/community/forums/t/681818/" onclick="window.open(this.href);return false;) that this is "normal behaviour" for this species, it either still needs to develop its root structure further or it might even be a way to reproduce?

[george76904]

While it is normal for it to be sprawling. Yours are in need of more light. I have one that is completely erect even though it is about 15 inches tall. It should be thicker than the pictures show. I promise that with more light the new growth will be different.

[greenknight]

Yes, it needs more than a couple hours of direct sun.