I'm stumped about one of my plant. It's currently 5 ft tall and have 3 buds growing. But I noticed the stems went from plump to skinny. It's the S8. I have another S8 that is about 4 ft tall with 2 buds. But the stems on that on is still plump. Is there a reason why it goes from being plump to skinny. Am I not watering enough? I water them max 2 times a week , sometimes one.
Skinny stems, ones that look more like actual branches and less like 3 sided 'finned' dragon fruit stems are usually caused be a lack of sunlight in my garden. My particular growing scheme means I have a lot of undergrowth if I don't keep things trimmed as much as I should and the new growth that is under eves or the plants canopy, meaning its shaded all day, will grow just as rapidly in length, but they don't have the plumpness to the branch as would be typical. Having said that, the internal woody core of the plant, its main circulatory '"artery" will still be of normal size and growth capacity. Think of it as a skinny kid with normal bones; the plant looks weaker but everything's still working. Now, if you have a main stem or runner that has this going on, as soon as it does manage to get back into a sunny area, it will resume growth normally, so you can allow these types of stems to remain if you want to use them for main runners or to shape your plants. As soon as normal conditions resume, normal growth should follow.
Of course, this is how it works here. It is possible that you might have a situation that, if sunlight isn't the issue, you might be lacking in a particular nutrient that the plant needs for proper development, but that would be on a case by case basis, and you would have to see what works for you. Or just go with an all in one type fertilizer and weed out the problems that way.