Designing for Disaster?

First, before I get rolling with this week’s blog from the Gardener on Main Street, I would like to offer a rarefied Happy Leap Day to all. Now for the main event: designing a garden for natural disasters.

My mother-in-law shared with me an Associated Press article which was published nationally a few weeks ago, and was picked up by some midwest papers. At first glance, there were a number of interesting points, but then some red flags arose. It is important when reading gardening tips and advice (including this humble blog) to consider the author and the author’s context (location). Most of what the author, and other experts quoted, discussed in this article applies to Florida and west coast states like California who deal with prolonged rain/high wind events (i.e. hurricanes) and wildfires annually.

As a quick aside, I would like to point out that I think of “design” differently perhaps than the standard use of the word in practice. Normally, the design of a landscape describes an early phase in building a garden, which then transitions to a maintenance phase with occasional upgrades down the garden path some day. “Design” in Wellfield/botanic garden terms describes the whole gardening experience and is a systems approach. Design refers to a cyclical process of creation, fostering growth, feedback and redesign, so when you are performing “maintenance” in the garden it is really a series of mini design decisions. You are designing the world around you all the time, thus most “failures” in the garden are design failures.

Okay, back to the article. My first “beef” with the article is the subject of the headline: plant selection. I would never “design” a landscape with natural disaster as my primary consideration when selecting plants. I would put greater emphasis on how different elements are arranged/interrelated within the design and how the plants are treated. The care and environment in which the design is installed is as, if not more critical, than plant selection criteria when it comes to resilience. For example, in a great University of Florida report discussing the effects of hurricane events on urban tree canopy survival, I noticed a good portion of the article focused on maintenance and environmental factors affecting trees and shrubs under severe wind/rain stress.

My second beef with the article relates to the first in that the author quotes an expert recommending native trees over exotics as a plant selection criterion. This is too broad of a generalization. Just because it is “native” to a region does not correlate with hurricane resistance. Plants have many different survival strategies, of which the biomechanics of the plant structure is only one. A native species might be ripped to shreds, but readily seeds as a means of preserving the gene pool, for example. Just because a plant is “exotic” does not mean it is any less likely to survive. Better to select plants based on their habitat of origins. If an exotic species evolved under high wind conditions naturally, it might be a good candidate. Critical thinking is required here.

As another aside, the article suggests planting species that lack flammable waxy coatings or resins, especially suggesting the avoidance of conifers. There is so much wrong with this, I hardly know where to begin. First of all, many pine species evolved in fire prone regions, thus they are naturally fire resistant. Second, selecting plants lacking waxy coatings is selecting species which might be less drought tolerant. Nothing like a dead, dried up plant to resist a fire, eh?

Just as important as plant selection is the plant’s function in the design. One could use microclimates to shelter a desired vulnerable variety. One should always consider a site’s dominant wind vectors just as one thinks about soil type, light levels and annual rainfall.

Another design strategy is to plant in groups, in resilient plant communities. Diversity and relational complexity are great ecological principles to utilize in natural disaster prevention. How plants are arranged is of greater importance than individual plant characteristics. I would look to arch-habitat types as inspiration for how to arrange plants to survive. How do forest or grassland species endure these types of extreme events? They survive working together, so draw inspiration from such models.

Beyond design considerations is plant care with respect to garden natural disaster prevention. Regular removal of dead and diseased limbs and whole plants is critical. Keep canopy trees properly thinned to offer the least wind drag. Give plants the needed root zone to grow. Make sure the garden is adequately watered, etc. Utilizing all the best practices creates naturally healthy, resilient garden plants.

The Midwest is less prone to fires and hurricanes, but strong wind, ice storms, flooding and drought are “disasters” we face. To help your garden weather any climatic extremes, incorporate swales, windbreaks, and plant communities in your design decisions, along with good plant selection, for best results.

Josh Steffen, Horticulture and Facilities Manager