It's hard to think about what your garden will look like when it's frozen solid and/or under all that snow, but the time will come and it will be none too soon for me. Then I will lament time not spent planning the changes I wanted to make to get the best from our little slice of heaven. Fortunately, in a season without trade shows, there’s no lack of industry updates about gardening. One topic that continues to get attention is the use of natives in home landscapes.
WHAT ARE NATIVES?
This is a point of heated discussion in many gardening circles. I like the simple concept of natives being plants that were here before European settlement. Some believe that if a “mother” plant is naturally occurring, then all results of hybridizing that plant makes them all natives. A stretch, to be sure. But the key idea here is to look at a plant for what it contributes to the natural order of things. With that in mind, a native plant would have several characteristics: create wildlife habitat, be well adapted to the vagaries of local weather, and be low maintenance, i.e., exist without supplemental irrigation, fertilizer or pesticides. But its most important characteristic is that the plant supports caterpillars and/or pollinators: the more, the merrier.
THE IMPORTANCE OF CATERPILLARS
Let’s look at the importance of caterpillars. The simple answer to why they are so important is they are the primary food source for birds, especially hatchlings and chicks. That’s because caterpillars are soft (no hard outer layer), large, nutritious, and especially high in carotenoids, which give birds their signature colors. If you follow the link from birds, you recognize that birds are also important because they keep systems in balance by consuming insects, fish, and larger prey. They pollinate plants, disperse seeds, scavenge carcasses and recycle nutrients back into the earth. Simply put, without birds, we wouldn’t be able to survive very long. So, another way to look at natives is to ask: what does the plant contribute to either pollination or the survival of birds? Is the plant food for a caterpillar or an insect that a bird will consume? Does the plant produce a flower that pollinators can access (not all flowers have accessible pollen)? When you examine a plant using those criteria, you can easily deduce that some very popular plants like Japanese Barberry (Berberis thunbergii) are not native. It came here in 1875 and is loved by homeowners for two reasons: deer avoid it, and it sports colorful red foliage at the end of the season. In terms of bird food, barberries produce bright red berries in summer, which birds consume. You would think that is a good thing, but it’s not. First off, those berries are not nutritious for the birds. Second, the bird droppings from these berries create more plants (nature’s way). Third, the plant proliferates just about everywhere to form dense stands that out compete native trees and herbaceous plants.
The reason is their leaf litter changes the pH of the soil, making it more alkaline, which further excludes many native plant species. But here’s the worst of it: it turns out that barberries create a nice, moist environment at their base which deer ticks love. So now you have a tick population issue besides having a purely decorative plant with no nutritive value that takes over. The good news is you can get a deer resistant plant with magnificent fall color by simply replacing your barberry with a Fothergilla (Fothergilla major). That plant has lovely fragrant white bottlebrush flowers in spring for early season pollinators and closes out the season with brilliant red foliage. In between, several species of caterpillar forage on it.
No need for barberry anymore. Exactly how many caterpillars do birds consume? Some studies show chickadee nestlings may consume between 6,000 and 9,000 caterpillars before they fledge, all foraged within a 150-foot radius of the nest. The entomologists will tell you that insects tend to be specialists. They eat and pollinate mostly plants with which they share an evolutionary history (Forester et al. 2014). Generally, however, insects don’t adapt as well to feed on unusual or strange species, i.e., those that came from outside the area. Sometimes even within the same genus, introduced plant species provide much less food for insects than natives. See that word “introduced?”
HOW TO ADD NATIVES TO YOUR LANDSCAPE
So now that you know this, you might ask how do I add more natives to my landscape. It’s actually pretty easy, thanks to the many scientists and horticulturists who have been working on this issue for several years. One result is the Native Plant Finder, courtesy of the National Wildlife Federation. You just go to their site, plug in your zip code, and up comes a collection of plants for your consideration. Then all you have to do is examine them to see if they fit your needs (size, color, light, etc.) to make your decision. What could be easier? As an example, I looked up Witch Hazel and learned the native species in my area is American Witch Hazel (Hamamelis virginiana). It’s one of my faves because it delivers lovely yellow flowers in early winter when just about everything else has finished flowering.
That makes it very beneficial for late season pollinators as their food supply is greatly reduced by then. More importantly, it is a caterpillar host plant that attracts 68 species of butterflies and moths. Perfect! To get a more ecologically balanced landscape, you don’t have to completely remove all your non-native plants. Fortunately, the use of natives isn’t binary. Native plants can play well with others so your landscape can have a mix of natives and non-natives and still be beneficial to the environment. Like most things in life, it’s a balance. Rather than having an ecological desert, try to mix in some native plants. They can be grasses, shrubs, trees, perennials, etc. Aim for about 70% of your total landscape and you will be rewarded over time with more birds and wildlife and a general improvement in the health of your yard.
Written by Lorraine Ballato, author of Success With Hydrangeas, A Gardener’s Guide.
