Arid zone plants stab their neighbors to death. It’s an adaptation to limited water by using sharp weapons to tell others to back off. It’s also a consequence of growth and time and distance between plants. Small succulents and cacti you planted a while ago may be much larger and touching each other in some places. If it’s the wrong place, you have conflict.
For example: The wicked tips of a big agave touch a fence post cactus. First, the thorn scratches the smooth green skin, then, it grows longer to gouge and penetrate. This starts an infection in the fence post. It dies back, and big daddy agave wins all the water intended for the fence post, unless you step in to resolve the conflict in advance.
With nearly every plant bearing spines or thorns of one kind or another, potential for growth injury is perpetual. The closer your plants are to one another, the greater potential for unauthorized sword fighting. Most of the time, you don’t know it’s going on until the victim inexplicably dies.
The problem is when the wind blows. Long sinuous branches are whipped around in every direction to impact adjacent plants. From breakage to blow over, the outcome of sword fighting are injuries, disfigurement and eventually death. When you pay $1,000 for a big specimen succulent, sword fighting should be strictly outlawed. It’s the only way to protect the investment. Once its beauty is marred by another plant, it’s not perfect anymore, so the value of that specimen decreases exponentially. It looks bad, too.
When sword fighting goes on in your garden, three possible outcomes result. Each are unsightly, unhealthy and best resolved as soon as possible.
All it takes is one wayward branch to spoil a specimen. Scratches on the skin of the plant are your first clue there’s sword fighting going on. Study the scenario and determine its cause, then assess how you can make judicious pruning cuts of spines, stems and branches to resolve the conflict before it progresses. Once the clean skin of a cactus or the smoothness of an aloe are compromised, there’s no easy fix until it grows out years down the road.
In windy areas, plants are always buffeted. This turns the early scratches into deeper disfiguring abrasions. For example, thorny palo verde tree limbs are always rubbing on one another. Where these come together, the green skin is worn off to brown scabs and scars where sap oozes to attract bark pests.
Puncture wounds are caused by a sharp spine or thorn impaling itself into soft flesh of succulents and cacti. It often happens slowly as a plant grows larger, its spines coming in direct contact with an adjacent plant. Each millimeter of growth pushes the spine a bit deeper into its neighbor. Moisture oozes out to attract bugs and rot to the wound, which does not heal. Punctures can occur quickly, too. Spiny ocotillo stems often slam into a smooth cactus with abnormal winds. It will happen again and again unless that ocotillo is pruned accordingly.
It’s important each year to assess your spine/thorn damage potential to break up the fights. Do it with a strong pair of sharp, pointed hand clippers and long-handled loppers. Snip branches and spines wherever scratches are starting. Study the intersections of spiny cactus and yucca and agave where their sharpest distant points can be cut back to allow a few inches of clearance.
While examining cacti and succulents for battle wounds, wear your reading glasses and gloves.
Use the opportunity to remove dead growth, look for signs of pests and prune out any damage you can. Go plant by plant studying the nature of their sword play and resolving the conflict by protecting one or the other.