Native Plants, Our Future
Garden Design Round Table
Written by Douglas Owens-Pike
We are blessed to be present during one of the greatest upheavals in nature during the several billion year history of this planet. Blessed, because we have the opportunity to make a difference. Mounting evidence shows that we either change our habits and move toward more sustainable fuels (probably not corn ethanol), or the massive redistribution and possible extinction of the plants and animals we depend on for food, as well as native plant communities, will be upon us. The shift in rainfall from the breadbasket of North America further north this growing season could be a glimpse into a hotter planet. Some theories suggest that this shift is a result of less ice covering the Arctic Ocean which in turn may be forcing the jet stream to guide rainfall north.
What does this ecological upheaval have to do with landscape design? Let’s begin with trees. Trees are one of the primary ways we can cool our planet and make outdoor living spaces more comfortable in the face of increasing heat. Unfortunately, in recent history, many regions of the United States have suffered from tree decline due to the combined forces of introduced insects and diseases together with the stress of mixed up weather patterns. Trees should live for several human generations, if we pick the right species. Right requires some understanding that our future climate will probably be quite different from what we have known. As an example, here in Minnesota, we have a tension zone that separates the prairie region of the SW from the northern hardwood forests of the NE. The current expectation is that this boundary will shift from the center of our state to the farther NE corner. In light of this boundary shift, we should think about planting trees that will prosper in this new, hotter, and probably more drought ridden climate. What choices do we have? We can begin with native trees usually found on the edges of drier habitats: several oaks come to mind as well as hackberry. Additionally, Boxelder which is normally thought of as a weed colonizing bare soil, could be ideal for some areas.
Underneath these trees we can plan for greater heat and drought stress by adding shrubs that meet our landscape priorities: screening for privacy, flower color, attractive fruit, and food for people or wildlife. Hazelnut, wahoo, snowberry, and others fit these criteria.
Ground layer can include plants that require little fossil fuel for care like sedges and fescue grasses that stay short without mowing. Flower beds can be attractive native meadows planted with an eye focused on the soil, sun and moisture available. The good news is that smart landscape design allows each of us to install landscapes that help reduce carbon emissions by storing them in long-lived perennial roots, as well as tree and shrub wood above ground.
Water is already a scarce resource on much of the planet, and we might want to plan on it getting more expensive here. If you irrigate your gardens, switch to low water use drip lines to prevent the high levels of evaporation that occur when we spray water into the air. Of course, with the right collection of native plants you will need no irrigation, except immediately following installation.
How do we determine the right native plants? Formerly, we looked to surrounding communities of native plants. While this approach still holds true, we will need to begin focusing on similar species from farther south, up to 200 miles even, of where we are designing. Many plants cannot evolve fast enough to compensate for changes to our growing season. Research has shown that people need to get involved if we are to save even a tough, native annual like partridge pea, Chamaecrista fasciculata. It thrives in desert-like, moving sand habitats from Gulf states to Canada. Yet, if you plant seed from Minnesota in Texas or the reverse, it will not survive. By going just a few hundred miles it seems to be just about right for the changing conditions. Normally, this annual disperses its seed up to 10’ by twisting its drying pods. Others move further, carried by water, but only people can move this seed north fast enough.
If you have been focused on horticultural varieties for your landscape designs, consider adding native diversity to your pallet. While doing that, look several hundred miles south of your location for inspiration. By doing so, these thoughtful landscapes will help some native plant diversity survive the changes ahead of us.
Thanks for reading!
To learn more about designing with natives, please take a moment to read the thoughts of other members of the Garden Design Roundtable: