Palm Trees for Tight Spaces and Small Urban Gardens

By Tyson Curtis

There are many challenges when planting a garden, including considering damage to retaining walls, sidewalks, foundations, and underground utilities. Often the easiest way to overcome these tricky spots is planting small plants that won’t have a large impact on nearby infrastructure. But what if you need a larger, more substantial element?

*Chamaedorea plumosa* in a garden designed by Christopher Reynolds

Palm trees are an excellent solution for this commonly encountered problem. This is because of their uncommon root structure. I know, we’re about to go all twelfth-grade biology right now, but this will help you understand why palms are a great selection for tight spots. Flowering plants are divided into several large groups; palms are in the monocot group. The other groups, which include the majority of flowering plants, are characterized by a primary root, called a taproot, that other secondary roots branch from. These roots expand downward and outward, getting longer and thicker over time, often damaging nearby structures and pipes. (The same is true of many non-flowering plants like pines, cypresses, and redwoods.) These roots literally jack the soil around them outward, applying incredible force on anything nearby. You most commonly see this force in the familiar buckled sidewalk.

Monocots, on the other hand, are characterized by a web of roots going in all directions from the base of the plant. These wiry or fibrous roots occupy a relatively shallow area of the soil and move around infrastructure, rather than shoving it aside. These fibrous roots also make transplanting most monocots much easier. Common monocots include grasses, bamboo, orchids, most bulbs, bromeliads, aloes, agaves, and, yes, palms.

*Chamaerops humilis* (Mediterranean fan palm, on left)

The monocot root structure also makes palms a good choice for group plantings, because the roots don’t compete with each other as taproots do. For the same reason, palms are excellent choices in pots, since they are unlikely to crack the pot. Their scale also remains in harmonious balance with the pot. For example, a Trachycarpus wagnerianus will grow 15 feet tall in 20 years when planted in the ground, but the same palm planted in a large pot will stay under four feet tall. The leaves will also stay smaller and in balance with the plant’s overall proportions. Generally smaller palms tend to look more vivacious and do better in containers. Some of our favorite palms for pots are the above mentioned Trachycarpus wagnerianus, Chamaedoreas (including C. metallica and C. ernesti-augusti for very small pots), Chamaerops (Mediterranean Fan Palm), Syagrus weddelliana, Phoenix roebelenii, Rhapidophyllum hystrix, Rhapis palms, Trithrinax, and Howea (Kentia).

*Trachycarpus wagnerianus* (pots) and *Trachycarpus martianus* (foreground)

Stroll through any older California neighborhood and you’ll likely find a heritage Phoenix canariensis (Canary Island date palm) growing happily in a front yard, shoved up against a foundation or clearly growing over underground piping. It almost defies logic that in a hundred years these trees haven’t damaged the infrastructure. At the same time, you may find one behind a retaining wall that has failed, leaning forward. This is most likely because the engineering didn’t consider the incredible weight of a full grown canary palm, which the wall must support. So while the roots aren’t a threat to retaining walls, be sure your walls are built to support the weight of your trees themselves.

*Chamaedorea costaricana* in a tiny courtyard garden in SF

If your space is tight above ground, where the palm fronds will be, try a palm with a slender profile. Some narrow palms that we love are Chamaedorea plumosa, Chamaedorea radicalis, Chamaedorea woodsoniana, Howea (Kentia), Rhopalostylis, Parajubaea sunkha, Oraniopsis appendiculata, Phoenix roebelenii, and Hedyscepe canterburyana.