Early American pioneers always knew the north side of the tree produces moss. In the woods, this knowledge saved many lives. In drier climates of North America, it’s the barrel cactus that is our most reliable orienteering plant for barren desert conditions. Here, each one will lean to the south to access the maximum amount of sunlight year-round. The lean is so reliable that Ferocactus cylindraceus, a common native is called “compass barrel.”
At the Huntington Botanical Garden, a massive old collection of golden barrel cactus demonstrates this isn’t just true of native cactus. These Mexican cactuses are now the size of a garbage can, and they lean at the same angle as if all are straining to hear a faraway song. It is the solar melody they seek.
But not all cactuses are so obvious about their awareness of the sun. This is because branching cactuses are not such a symmetrical form. Their tissues are dividing all over the plants at various growth points to spread in every direction. But no matter how much they sprawl, prickly pear is just as aware of its orientation as the compass barrel, you just won’t see it as clearly. Even the native hedgehog cactus produces multiple stems that reach, however subtly, toward the equator.
Meristematic tissues are at these growing tips where plant cells are actively growing. The heart of a palm tree is highly meristematic as it produces new leaves and flowers from the very center. For a barrel cactus, the single meristem is at the very dense center of the top that is often ringed with flowers in spring.
This tells us something very important about relocating a cactus plant: They have a front side that should face south. Remember, a cactus can’t move itself to adjust to exposure change like an ordinary non-succulent plant. It can’t drop foliage where there’s insufficient sun or grow new stems and leaves once properly exposed again. They don’t speak as loudly in the silent language of plants, which is why gardeners often fail to recognize this preference.
Cactuses do not orient quickly. While we can turn a house plant so foliage will respond to the new light source, a cactus cannot move itself at all. Therefore, it’s very important to establish the primary direction of your cacti and keep them so oriented for their entire life.
Know the original orientation whenever you’re relocating a potted cactus or transplanting one for any reason. Before moving the pot, note its previous orientation and the side where light originates. To help you remember, mark it on the pot with a Sharpie. That mark must face the same orientation (south) no matter where the pot goes. Anytime you move that plant to clean or reorganize, take a minute to ensure it’s replaced with the exact same orientation
This is equally important when transplanting cactus. Many nursery grown cactuses are raised in lighted greenhouses so they don’t know what south is yet. It begins only after that plant comes into natural sunlight and day length. Once you bring a greenhouse cactus home, establish an orientation that works for you and then keep it that way as the plant matures.
When transplanting cactus from one location to another outdoors in the ground, always mark south on the cactus before you dig it up. It’s easy by tying a piece of yarn securely to the spines. Failing to do so can leave you with no idea how to orient if the plants are stored in between without markers.
Be kind to your cactus and remember that they love the south. Pay attention to orientation and keep it consistent and maybe they won’t notice too much of you move them. And if you’re ever in doubt about finding north in the desert, just look for the lean that always points south. Who knows, a barrel cactus may save your life one day.
Maureen Gilmer is an author, horticulturist and landscape designer. Learn more at www.MoPlants.com. Contact her at firstname.lastname@example.org or P.O. Box 891, Morongo Valley, CA 92256.