Natives vs. Exotics: Which are Better in the Garden?

Who among us has not encountered at least one person (not always a gardener) who wags a judging finger when we admit our gardens include both native and non-native (also called exotic) plants? This natives-only stance is not only annoying, it’s also wrong-headed.

What’s the difference between a native and non-native plant? Plants that are native to North America have evolved and grown over thousands of years in a specific region before European settlement. Non-native or “exotic” plants, on the other hand, have been introduced in one way or another to an area in which they did not naturally grow.

Walk through any garden center, and while you may see a few native plants, what you’ll mostly encounter are exotics that have been bred and cultivated to offer benefits like bigger or longer-lasting blooms, disease resistance, or standout color.

Many gardeners, including me, love non-native plants because of the diversity they bring to the garden. This doesn’t mean we exclude natives, but we do have a mix of plants, and maybe even a preponderance of non-natives at home. As interest in natives has grown in recent years, so has their availability, as well as the debate over which plants are the best choice for home gardens. This debate is more complex than it seems, with some of the arguments breaking down as follows:

• Native plants are more pest and disease resistant than exotics. This is true in the sense that native plants are better able to withstand attacks from native pests and pathogens. But they don’t fare any better than exotics when faced with terrors like emerald ash borer, Dutch elm disease, Asian longhorned beetle, and white pine blister rust.
• Native plants are more drought resistant, so they can be grown more sustainably than non-native plants. This is true when natives are planted in places that offer the conditions they need to thrive. If you’ve got the perfect spot for a native prairie garden, by all means, plant one. But plant a native sugar maple in a sandy spot and it won’t be around to enjoy for long, since it needs loamy clay soil.
• Native plants offer better habitat and sustenance for insects, birds, butterflies, and wildlife. Again, there is truth here. Over time, all of these creatures have adapted to use what native plants offer. This discounts the fact, though, that many non-native species offer the same bounty, cover, and protection. What is truly at issue, some ornithologists say, is whether more and more birds that used to migrate are now sticking around to snack on the offerings of non-native plants when, sadly, some of these plants don’t offer seeds and berries with enough fats and nutrients to sustain birds through the winter. The birds may eat heartily, but it won’t be enough to keep them going through the long, harsh months so they don’t make it until spring.
• Non-native plants are invasive. People often lump non-native species in with invasive plants that take over landscapes, destroying ecosystems and choking out native plants. In truth, only a small number of non-native species are invasive—think kudzu, which is taking over the south.

Rather than taking sides on this debate, it seems more prudent to accept that both native and non-native plants have characteristics that endear and alienate gardeners. Though it can’t be qualified with research or backed up by studies, one of the best plain-and-simple reasons gardeners include non-natives in their landscapes is because they like them. Gardeners who limit themselves to natives miss out on the benefits of centuries of plant cultivation and innovation. Plants like gardenia, evergreen azaleas, Japanese maples, and Norway spruce are well-behaved, non-native species that look great in the garden and perform well in the right circumstances.

Of course, no gardener should knowingly plant an invasive species. Before adding something new to your garden, check with your local extension service to get a list of plants considered to be invasive in your area. You’ll find a list of extension services here: http://www.nifa.usda.gov/Extension/index.html. If you don’t have an extension service, check the Nature Conservancy’s Web site for detailed information on invasive plants: http://www.nature.org/initiatives/invasivespecies