How to Grow Dragon Fruit (Grow Pitaya Fruit / Grow Pitahaya Fruit )
Origins of Dragon Fruit / Pitaya Fruit and Climate: Dragon Fruit is native to South and Central America, and as you would guess from that history, too cold conditions or cold winters will kill the pitaya cactus plant long before the pitahaya cactus plant successfully fruits at all. In fact, although it has characteristics of a cactus, the pitaya plant will not tolerate conditions that are oppressively hot either (don't think of Joshua trees in Death Valley). Think of the pitahaya cactus plant more as a tropical find than a hot desert cactus. In spite of the pitahaya cactus plant not being native, the climates of Vietnam and Thailand suit the needs of those wishing to grow pitaya cactus plants well, and it is commercially grown successfully in both Thailand and Vietnam as a result. In the United States, mild climates like Southern California are amendable to growing pitaya cactus plants. Growing pitahaya cactus in greenhouses is also possible.
Obtaining your first Pitaya Seed(s): If you can buy pitahaya seed already prepared and ready to be planted, go ahead and use those as your dragon fruit seed(s). If you do not have ready access to pitahaya seeds prepared and ready for cultivation, just go ahead and harvest the dragon fruit seeds from either the fresh pitaya fruit (save some next time you are eating) or take your pitaya seeds from your dried pitaya fruit. To get the pitahaya seeds from the fresh fruit, just gently mush the flesh with a little bit of water to wash away and remove the flesh from the dragon fruit seeds. Treat the dried fruit similarly, but you will need to be more delicate and careful. You may need a little more patience and perseverance if you harvest and prepare your own pitaya seeds from the fresh or dried pitaya fruit, but just keep at it and most likely you'll find enough viable seeds to get seedlings from them.
Getting the first Pitaya Plant Seedlings: Plant the pitaya seeds in (very shallow placement) a well draining potting soil or potting compost material and either keep the planted seed material moist, or better yet cover with a plastic bag or use a small greenhouse type of setup to keep the seeds moist. Make sure you clean off any residual flesh from the pitahaya seeds before you start them, as the left over flesh clinging to them can easily rot and spoil your planting. You should within 10-14 days or so begin to see the first seeds sprout and produce seedlings. Transfer them to a rich but well draining soil mix and keep temperatures moderate, and the pitaya plants should begin to take hold. Do not over water the growing pitahaya cactus plants! Give them a support on which to grow as they begin to mature and increase in size.
Growing Pitaya Cactus Plants from Cuttings: If you don't want to wait and enjoy the reward of seeing a seed burst forth into a seedling, and you have access already to a growing pitaya plant, you can try to grow pitaya cactus directly as a new plant from a cutting or section of the mature plant. Like other succulents and cacti, if you break or cut off a large enough piece of a mature plant it will attempt to put down roots and start growing itself to form a new plant. Try cutting a section of the mature pitaya vine (stem) and plant it directly in the ground or suitable soil medium. You may have trouble with the cutting rotting before it successfully starts growing, but with a little luck you will be growing pitaya cactus plants quickly without having to start from seeds. You should expect, if your pitaya cactus cutting section was large enough, blooms in 6 - 12 months - a significant savings in time from starting from seed.
Growing Pitaya Cactus Plants to Maturity / Fruiting: As for many fruiting plants, the very young pitaya plants will not liberally flower or fruit at all until they have begun to reach some degree of maturity. The vines of the pitaya plant will have to reach a moderate size and weight (many lbs) before the pitaya plant will start to flower and bear fruit. At a minimum you should not expect fruiting and flowering for many months - unless your pitahaya cutting was huge enough to really be a mature plant already when you planted it!
Seeing the Mature Pitaya Plant to Fruiting: Because the pitaya plant blooms only at night and the blooms are fleeting, it can be hard to achieve successful pollination required for the pitaya plant to bear fruit. Many of the insects that pollinate other flowering plants are not active at night. Night active pollinators like bats and moths are more likely to pollinate the pitahaya plants than bees and other day active pollinators. Depending upon where you are in the world this can present a problem. One might say this is where the art comes into the process. Have patience, however, as the plants will usually bloom several times each year depending upon your climate and growing conditions. You may have to resort to hand pollinating the plants yourself.