4 cuttings in 15 gal pot is ok.

Hi

You can grow 4 or 5 cuttings in a pot. If you have only 1 cutting in a pot, you will not have much fruits. Since the roots of dragon fruit are not too big, you can grow 4-5 cuttings in a pot. You can buy more cutting or divide the next segment but don't cut it too young or too short, a good size you can cut is around 16 inches. You have to wait for around 2 years to get 3 more cuttings :)
Hope it helps.

Thanks, that's exactly what I needed to know. I repotted the cutting I had (I think it's a Voodoo Child from Home Depot) and it had a surprising amount of roots on it. Off your advice, I think I'll go with a second cutting, maybe a Physical Graffiti or something crazy. Can I take a big 18" cutting and divide it up into 3 or so pieces? Or do you recommend sticking the entire 18" piece in the ground?

Don't cut it into 3 pieces. You might have to wait for very long time if you grow cuttings of 6". Just stick your 18" in the ground now and at the end of this year you probably get another cutting from it, and the plant you have now will give you another cutting at the end of the year. So you will have 4 plants/cuttings at the end of this year.
By the way, did you purchased you plant from Home Depot? When did you purchased it? As I know Home Depot doesn't have Voodoo Child anymore, now they have HYLOCEREUS POLYRHIZUS.

Hey Nguy, thanks for the info! Makes sense to start them off bigger.

I got my cutting from Home Depot just two weeks ago. The label does say H. Polyrhizus on it, but shows a picture of a voodoo child fruit. Isn't H polyrhizus the same thing as voodoo child (see link)? Aren't they all polyrhizus or am I missing something? And do you know who supplies Home Depot with these dragon fruit?

Here is a link that might be useful: Voodoo Child

Hi Jay,
Voodoo Child is a H. polyrhizus HYBRID. Please check the link below for more info about H. Polyrhizus. H. Polyrhizus is not a self-pollinating variety, so it needs hand-pollinating. Voodoo Child variety is self pollinating. Also you can look at the thorns on the stem. Voodoo Child has single thorns, H. Polyrhizus has single thorns and many multi-thorns.

My uncle got 2 plants from Home Depot 3 years ago, 1 red flesh (H. Polyrhizus) and 1 pink flesh (H. Untatus). The pink one has a lot of fruits but the red one doesn't have any fruit. He told me the problem of the red one a few weeks ago and I told him the H. Polyrhizus needs hand-pollinating. So just wait a few months to see if he get any fruit.
Home Depot gets dragon fruit plants (and many other plants, & trees) from La Verne Nursery (please see the label on the pot). You might call La Verne Nursery and ask about your dragon fruit plant.

Here is a link that might be useful: H. polyrhizus

Ah, that makes sense. The cutting has multiple thorns, mostly 2 and 3. And I checked the label -- it is from La Verne. La Verne doesn't list it on their website so I'm thinking about returning it and getting some proper cuttings now that I know what's up. Thanks for the help!

Yeah, I think you should return it or exchange for the pink-fleshed plant. I heard several people said the red-fleshed plants from Home Depot and Lowes do not produce fruits if you don't do hand-pollination. My uncle said the pink-fleshed fruits are sweeter than his white fleshed dragon fruits.
If you want to buy Voodoo Child, you can find it on Craigslist. I have seen several people in LA County selling it (check the link below).
Good Luck

Here is a link that might be useful: dragon fruit cuttings

Awesome, thanks again for the help!

I have a 25gal plant container and 6 dragon fruit plants can I put them all in the container together?