Cacti in the Southeast

by Tony Avent Reprinted in the Carolina Gardener Magazine 1994
I guess we've all driven through the country side, and seen the mounds of prickly pear cactus adorning dilapidated mobile homes, so often used in those tastefully painted tractor tires. We've seen them so much, in fact, that they have just become a part of the southeastern landscape. Occasionally, they are complimented by the typical green yucca, but that's about as close as the southwest gardening culture gets to the southeast.
I always figured if this one ubiquitous cacti would grow outdoors in the south, there must be others that would fare equally as well. We began to search out seed sources and plant sources, of which there are several that specialize in hardy cacti. Before long, we had created a garden that would make our southwest friends proud.
Granted, there must be a little antisocial tendency in anyone who would actually grow hardy cacti, either that or an affliction for pain. Cacti are indeed a curiosity, with their enlarged leaves called pads, composed of mostly water, and an uncanny ability to thrive in the hottest, driest, and most adverse of conditions.
While there are some truly spectacular cacti plants, just like orchids, the beauty is in the flowers. Yes folks, cacti actually have flowers, and not those artificial ones that the discount stores stick in the pads to sell you something with color.
The reason that more folks have not tried winter hardy cacti in the southeast is our wet winters. In the southwest, they will often have no rainfall from early fall until spring. Cacti are much hardier when they remain dry. While some of the opuntias don't seem to mind the winter precipitation, many of the other genera of cacti must be sheltered from the winter moisture.
My first real success was with the cholla cacti, Opuntia imbricata. I figured anything that looked like a prickly pear would grow, but I wanted something a little different. Opuntia imbricata is a tall growing cacti to 8-10 feet in the southeast (The finest specimen of O. imbricata in the state is at Stoneville Nursery, just outside Reidsville, NC.)
Opuntia imbricata has joints that resemble green cigars with white spines that are jointed on the ends...I know this sounds real strange. After Opuntia imbricata survived our winter temperatures of -9 degrees, I figured that hardy cacti deserved more room.
My first cacti and succulent garden was installed when I was landscape director of the NC State Fairgrounds in Raleigh. The garden installed in 1991 features over 200 hardy cacti and succulents, and is still intact on the fairgrounds, just outside the entrance to the flower show area.
In designing the garden, we used cacti that provided different forms, textures, and colors. The dominant genus of cacti was the opuntias, which are by far the easiest genera to grow in the southeast. Opuntias are found in a variety of shapes, colors, and sizes. The opuntia with the largest pad is naturally Opuntia texensis, the state where everything is "larger". If you want to dazzle your neighbors, then this is your plant.
For a strange but true variety, that looks to have been "beamed aboard a few too many times", try Opuntia engelmannii linguiformis. This unusual opuntia has pads that can be 24 inches long, and only a few inches wide. While most opuntia engelmannii forms look pretty common, this bizarre looking clump is guaranteed to draw more than a few stares.
If spines are your thing, you must try the Opuntia phaeacantha and Opuntia polyacantha, which have the longest, fiercest spines of any hardy cacti species that we have grown. There are a number of sub species of O. phaeacantha and O. polyacantha, each being distinguished by the color of their spines, such as O. phaeacantha rufispina (red spines). Most of the Opuntias, such as these species have typical large yellow flowers.
One of my favorites is Opuntia microdasys, the teddy bear or rabbit ear cacti. This spectacular clump has tiny spines, called glochids, that appear safe to the touch. Don't be fooled, as these glochids are incredibly difficult to remove from the skin. The two most common forms are O. microdasys albispina (white spines), and O. microdasys rufida (red spines), both bearing bright yellow flowers. The bunny ear cacti are reliably hardy when given protection from winter moisture, but may succumb to rot in wet winters.
On a larger scale, a fabulous light gold spined cacti with a similar shape to the bunny ears is Opuntia scheeri. The bright gold flowers, which like many opuntias, change gradually to a lovely salmon color, are a spectacular addition to this very structural plant.
Opuntia strigil is a large upright spectacular spreader. This is one that I raised from seed, and is certainly one of my favorites. The dark cinnamon brown spines make a lovely contrast against the green pads.
For something completely different, try Opuntia tunicata. This short clustering cactus has papery white spines, eventually making a dense clump. If you are looking for something distinct, then you must try this one.
If you are looking for a hedge to keep the neighbors kids, dogs, from trampling through your yard, you will need Opuntia leptocaulis. This cacti has pads that look just like long green pencils with bright yellow spines to 3 inches long. There is nothing that I have ever seen, including most army vehicles that would dare to penetrate through this cacti.
Another wonderful use for some cacti is for groundcovers. There is nothing quite as lovely in flower, as indestructible through our weather, and as deterring for foot traffic as Opuntia humifusa. This southeast and southwest native is truly the plant for gardeners with brown thumbs...as it rapidly spreads sideways, never rising higher than a few inches when covered with yellow flowers. When we lived in town, we grew this cacti in the 12" wide strip between the sidewalk and the street, where nothing had ever succeeded.
If you are scared by the height and growth of many of these cacti, try some of the dwarf rock garden types. Opuntia fragilis, Opuntia clavata, Opuntia pusilla, or Opuntia schottii. These opuntias are slow growing when started, and although the will pick up steam when established, they are very small and easy to watch over.
Another good group of cacti to try are the Echinocereus. These barrel type cacti are much more refined in size and appearance that the opuntias. The are very sensitive to winter moisture, and must be kept dry. This can be accomplished by putting flower pots over the plants in the winter or by building a cold frame top, over the bed.
Other groups of cacti to try include the Coryphantha, Echinocactus, Neobesseya, and some mammillarias. As with the Echinocereus, these cacti need protection from the winter moisture. These cacti are for the most part clumpers or barrel type cacti that will pose no problem as do some of the more aggressive opuntias.
Cacti look their best from late spring thru summer and fall. In the winter, the cacti become limp as the pads freeze and thaw, and are at best, unattractive.
The most common mistake that folks make in planting cacti is trying to duplicate their native environment...sand. In the plantings that I have made, the beds were prepared as are all beds in clay soils...add plenty of organic matter. Our beds at the fairgrounds were rototilled 10 inches deep, adding ample amounts of composted leaves. We also added a half inch deep layer of pea gravel for drainage that was also incorporated into the mix.
A high pH is also important, so don't forget to get a soil test before you begin. A pH somewhere in the range of 6.2-6.5 would be wonderful, although cacti will persist in a wide range of adverse conditions. In our well prepared bed, we saw cacti grow from one pad to clumps 3 feet tall by 3 feet wide in less than two years.
Most cacti ordered through the mail will arrive as a single pad with no roots, but don't fear. On the large padded types, simply lay the pad horizontally on the ground and stand back. Don't even try to stand the pad upright...it's difficult at best and certainly unneeded. Within a few weeks, the pads will be rooted in and beginning to grow.
If you are trying some of the smaller types, or the barrel cacti, you may wish to set these in a pot of potting soil until they become established. Use the same technique, being sure to keep these pots in a well ventilated space with lots of air movement.
Another handy tip is to eliminate the planting site of all weeds prior to planting...nobody in their right mind likes to weed around cacti. One saving grace is that many cacti are quite tolerant of Roundup.
Growing cacti may never become the "new" New American garden, but we can make our neighbors at least stop and take notice, while making the neighbors dog take a short detour...here's to antisocial gardening!