A Gardening Journal
Must Have: Night-blooming Cereus
- Published: March 19 2017
A climate milder than your own can be shocking: there, plants you may have known only on your windowsill are thriving right in the garden. More shocking: their sizes and habits are quite foreign to those back home.
In New England, it's a surprise that any cacti at all can survive, let alone enjoy themselves. They do—OK, not the fifty-footers you might see in Arizona—but, still, true cacti. Even under ideal conditions, though, few will ever grow higher than your kneecaps.
The picture below shows a tropical cactus that's the opposite of the ones hardy up north: it's a vine that can climb twenty to thirty feet into trees. I discovered it while walking in Key West, where it was delighted to be hanging around—literally—over twenty feet high on the trunks and limbs of a shade tree. Its stems were rooted into the ground at the base of the tree, but sent out adventitious roots that attached to the tree and, so, held the stems steady as they grew ever upward. The stems were thick and heavy, and any that didn't achieve sufficient contact with the tree's supporting trunk and branches cascaded out and down.
Vining cacti are easy-going, and all configurations of growth—upward, outward, downward—are advantageous. When the supporting structure is high, the cactus keeps climbing; if it's short, the stems that inevitably cascade soon touch the ground, where they root-in and produce all the more stems. If there isn't much of a supporting structure at all, the vines scramble along as a mounding groundcover, rooting-in as they wander.
Cascading stems that originate from high enough—I'm guessing eight feet and more—don't ever touch the ground. This is OK, too: the higher they are, the more sun they're likely to receive. Plus, their cascading orientation helps them flower and fruit all the more profusely. This is the same as for classic hardy fruit trees, whose stems are more fruitful when they pruned or espaliered so that they are not pointing straight up. If they rise only at an angle—or, even better, are horizontal or cascading—they are far more productive.
The cactus fruits are heavy, too, not just the stems. So the greater the number of stems that are cascading and fruiting, the greater the likelihood that segments will break off, fall to the ground, and take root. Do any of the stems shatter on impact? No problem: the exposed interior surfaces callus over, while the individual stem portions then send out roots. This same strategy of dividing the segments, letting the cut surfaces callus, then covering the callused ends very shallowly with soil to encourage them to send out roots is, in fact, how many segmented cacti are propagated.
The bouncing and tumbling during the fall also helps sever the stems from their hard round fruits, so the latter can roll even farther away. If in their journey they break open or rot or get eaten all the better: then the seeds are distributed more widely. Even stormy weather is a help, in that high winds could break off cascading segments—especially the highest and most exposed ones—and send them flying farther afield.
If stems are trained up four to six feet before they're allowed to cascade, the cactus will be less likely to look like a haystack. This cascade from the tree in Key West was so high that it was guaranteed to avoid haystackiness. Indeed, if I hadn't seen this tree from down the block, my casual gaze might not have extended high enough into the tree's canopy to have seen the cascade at all. Once I noticed it, the cactus's full extent was startling. The large cluster of pendulous stems in the center was about twenty feet above ground, but a stem or two were exploring far higher—seemingly, high out of sight—into the major limb angling up to the right.
This vining, self-clinging, tree-climbing cactus is one of a number of species of nocturnal-flowering succulents with enormous, powerfully-fragrant white flowers. Each is known in common parlance as a night-blooming cereus.
I've grown the upright (and really awkward looking) night-blooming cereus species, Epiphyllum oxypetalum, whose stems are stiff, thin, and light weight—they look like flat ribbons of kelp. But stems of this particular species are triangular and so heavy that they cascade readily. This species is likely to be either Hylocereus undatus or Hylocereus triangularis. Both are native to the New World, have thick green triangular stems, flower at night with incredible white blooms, and can climb high into trees.
More importantly for this gardener in New England, both of these frost-tender species are easily grown in a container. Garden-variety sources suggest, simply, that their lax but heavy stems be trained up a sturdy trellis to a height of four or five feet, by which time growth is tall enough (or—more likely—old enough) to begin flowering.
Another strategy is suggested by the training these Hylocereus species receive when grown for food. Their fruits are profuse, tasty, rich in vitamins and antioxidants, and colorfully showy. When raised as a fruiting crop, the cacti couldn't just be let loose up into trees: how could the fruits ever be harvested effectively when hanging from stems ten, twenty, thirty feet high?
Instead, stems are trained up posts so thick, durable, and high that they might otherwise be used as fenceposts. As they ascend, the stems are kept free of side stems, which maximizes accessibility to the developing plant as well as simplifying weed control. Stems that attempt to grow beyond the top of the pole have nothing further to cling to, and so cascade. As mentioned above, this downward angle is just what's needed to encourage flowering and fruiting.
Cascading also encourages dormant side buds that are vegetative to activate as well, so that the weeping canopy of stems becomes thicker and thicker. Occasional shortening of older stems that have already flowered and fruited encourages still more side stems to form.
Here's an entire field of night-blooming cereus being grown on posts as a permanent and easy-to-pick fruiting crop. This, then, is a true orchard just as much as if it were planted with apple or cherry trees.
Ornamentally, each of this cactus orchard's "trees" is a weeping standard that is a fraction of this scrambling, vining species' mature free-range size: a topiary, if you will. A Hylocereus standard would be a spectacular as well as a relatively practical container subject. In a large tub, it could be slid into a frost-free greenhouse during the cold months, where it would sit, dormant and unwatered, from late October to early May. Brought into heat and full sunlight in late spring, flower buds would soon form and—in just weeks after each bloom is done—so would the fruits. If the weather is hot enough and the season is long enough, several waves of flowering and fruiting happen summer into fall.
I wouldn't be growing my topiary of night-blooming cereus primarily as a fruiting crop, so it doesn't matter much whether I choose a form whose fruits are red or yellow with white interiors or pink. This Connecticut vendor sells a hybrid whose fruits have red interiors, but my real urge to buy its night-blooming cereus is because the vendor is within an hour's drive, not a mail-order nursery fifteen hundred miles away, where the climate is so tropical that these cacti can be sold as landscape plants. Shopping local is how I can see this vendor's more mature specimens: their stock plants. And, OK, also discover some other amazing plants to purchase.
I'll profile my container-grown Hylocereus as soon as it is mature enough to flower. Fortunately, this will be years before it's old enough to have taken shape as a weeping standard. Each trumpet-like bloom—which lasts only a few hours during the night—can be a foot long and nearly as wide at the lip of its "bell." As I recall from when I grew one of the Epiphyllum species of night-blooming cereus decades ago, the fragrance is so heavy and intoxicating you feel that you can see it wafting toward you.