Some plants that have self-sown profusely in the Irrigation-Free Landscape
We have always been drawn to the element of evolution in the landscape – how a landscape grows and evolves across the seasons, and over the years. It is what separates a landscape from a painting or another creative work whose ultimate form is intended to remain static over time. To these ends, we have increasingly sought out self-sowing plants that can be interspersed within a structure of more so-called placeholder plants (i.e. clump-forming grasses, perennials, and shrubs), so as to infuse a wildcard element into the landscape, which is then subject to the everchanging whims of nature. This all being said, is there a limit to how many self-sowing plants we should include in a landscape? It is a question that has been on our minds all summer, as we have observed many a plant in the Irrigation-Free Landscape self-sow with aplomb, to the point where even we’ve been surprised by their botanical fertility and vigor (this includes both native plants of the prairie and plants from other regions of the world).
The biggest problem that arises when plants self-sow so profusely is the difficulty in knowing which seedlings are weeds and which aren’t. A serious maintenance issue then rears its ugly head when the wrong seedlings are pulled or weeds are left to grow and take over the landscape due to lack of familiarity with the good vs. the bad. While we as landscape designers can most often easily tell the good from the bad, the task is more complicated for those who are less familiar with plants and who don’t stare at and ponder them for a living. Additionally, in a year such as this one, when spring was late, and early and mid-summer were very wet and relatively mild, you will find yourself with so many seedlings the landscape may start to look more like a weeding nightmare than a source of joy.
How then do you infuse that wildcard element into the landscape without letting it become a maintenance nightmare? The first strategy is to minimize the optimal growing conditions for self-sowing plants, or at least reduce their optimal growing conditions in quantity or quality. In our case, many of the drought-tolerant plants we use prefer extremely well-draining soil, including preferring virtually pure gravel. As such, one could reduce the total amount of area that contains this soil type and confine it only to areas where plants like lavender (which need perfectly drained, crummy soil to thrive) will go. The other strategy is to pick a bare minimum of a few self-sowing plants, and choose those whose seedlings are easily discernible from the ever-bothersome weeds that will always self-sow regardless of soil type (re: dandelions, crab grass, etc.). So, for example, Rudbeckia hirta seedlings are grey, rounded, fuzzy, and easy to identify, whereas Carex bicknelli can be hard to distinguish from turf grass if just given a glance-over. A combination of these two strategies could potentially yield promising results and the balance between rigidity and free-form evolution that we are looking for.
We will be infusing this new strategy into our latest landscapes and then shall report back with further observations.