Dragon Fruit Plants

These are photos of my seed grown dragon fruit cactus (Hylocereus). I have forgotten how many years old they are, but they have never bloomed. Reading online gave the info that the plants will probably not bloom till they reach a weight of  10 pounds. I believe mine weigh that much or more, but I have not actually weighed them.They certainly have long arms and very long roots growing from these. I bet that when  these "arms" eventually reach the ground, they will root and form new plants that will make a thicket in the back of my greenhouse. They are already a problem to navigate around as they have many small cactus spines.They flower at night and last only one evening. I guess the worst thing would be for one to flower and not notice it and miss the event of many years growing. (I frequently miss my night blooming cereus flowers- I simply forget to go out to see them.) These cactus are not self fertile so it would be necessary to have 2 plants blooming the same evening, to observe and be on hand, and to assist in the pollination of the flowers. Then there would be a chance for fruit.