Why Native Plants are Important

If you read this column on a regular basis, you’ve likely noticed me extolling the benefits of native plants. I, like most ecologically minded gardening writers, will tell you that native plants are good for the environment, that they use fewer resources and require less maintenance, that they preserve biodiversity … but what does all this really mean? Let’s take a look.

Are natives really low maintenance? Well, not totally. Native plants evolved here in New Jersey with our wet springs and dry summers, so they are better suited to this area than most exotic plants. They require less fertilizer and less watering. They do, however, need some maintenance, especially as young plants.

The natives you bring home from the garden center have been grown in pots, so their roots are just a few inches long. Since they have no way to reach down deep for water yet, they need just as much watering as any other plant you buy.

But, over time, they will send down deep roots. Very deep. Many native perennials have roots that go down 10 feet or more! While non-native daylilies have roots about two feet long, black-eyed susans reach down six feet. The spring-blooming native false indigo has 12-foot-long roots. By reaching down far for water, they eventually require less watering.

What about biodiversity? That term refers to the variety of life in the world, in a particular habitat or ecosystem, or just in our backyards. The more species included, the better. Variety helps sustain the ecosystem when problems occur, as with the invasive emerald ash borer that is currently wiping out ash trees in our area.

The wider the variety of native plants in your yard, the more birds, butterflies, and other pollinators you will enjoy. Even though it might look like your butterfly bush which originated in Asia is hosting lots of active butterflies, not one will lay eggs on it. Thus it is not supporting their life cycle. A native oak tree supports more than 530 species of butterfly, moth, and caterpillar. Many of these in turn become food for birds and small mammals.

Joe-pye weed, a tall native perennial that supplies nectar to many pollinators, is one of the few places many beautiful butterflies will lay eggs. This usefulness runs true for most native plants, so including them in your garden will attract more bird and insect visitors.

New Jersey has experienced a huge decline in the biodiversity of our local woods. I walk a path alongside Speedwell Lake in Morristown almost every morning with my dog. On a hot day in July, from one vantage point I could see many invasives: Japanese knotweed, garlic mustard, stilt grass, burning bush, porcelain berry, artemisia, invasive rose, oriental bittersweet, and barberry. There were also large patches of pachysandra and periwinkle, groundcovers that escaped from nearby gardens and crept into the woods.

How do non-natives proliferate? Non-natives get into the wild in different ways. A bird eats a berry from someone’s landscape shrub (barberry and burning bush) and poops the seed out in the woods. An aggressive seeder brought in from overseas escapes to the wild on the wind or from the bottom of someone’s shoe (Japanese knotweed, purple loosestrife, and butterfly bush). With no natural browsers, these species overtake the native plants and foster the decline in biodiversity.

I am always thrilled in the fall to find many native witch hazels still blooming along my path. And this spring I enjoyed three beautiful pink native azaleas in bloom. But these natives are lone survivors. Twenty- five years ago, the woods would have been festooned with veritable clouds of pink flowers.

What role does the deer population play? The overabundance of deer has led to the excessive encroachment of invasives. Native deer naturally have a taste for native plants as their meal of choice and don’t enjoy munching on non-native varieties. (See sidebar for deer-resistant native plants.) Once the deer eat away the natives, the gaps in the woods that remain are prime territory for non-native plants to exploit.

Why are natives so important long-term? A decline in native plants is soon followed by a decline in our insect and bird populations. Because we don’t have long-term data, it’s hard to find exact numbers, but local scientists and naturalists report that insect abundance and variety have decreased alarmingly in the last half century, due to land use change, pesticides, and pollution. As much as 45 percent since 1974.*

While my beekeeper friends might be thankful that the non-native Japanese knotweed is providing fall feeding for their bees, the knotweed has displaced native goldenrod and asters that historically fed fall pollinators and birds before migration.

Native plants sustain birds in a variety of ways. For example, birds require lots of fat to fuel their migration. Hummingbirds must gain up to 40 percent of their body weight by eating insects and nectar before they migrate, so they need plenty of fuel from these fall bloomers or they will not survive their 1,500-mile migration to South America. Most native berries that ripen in fall have a high fat content: spicebush, bayberry, arrowwood viburnum, grey dogwood, elderberry, and Virginia creeper.

While we do see birds eating berries from non-native Japanese barberry in the fall, we now know those berries are not providing the nutrients birds need to survive a cold winter or long migration. Many non-native berries like barberry and burning bush are high in sugar and low in the fat that New Jersey’s birds need to survive their migratory journeys.

Now you know why I and others have been sounding the alarm around the decline of native plants in New Jersey and elsewhere. When non-native invasives take over our woods, fields, and backyards, the local animal, bird, and bug populations take a big hit. Food is scarce or less nutritious, and shelter is compromised. Species go elsewhere or have the potential to die out. While rescuing our wild areas will be a real challenge, all of us can do something to help by planting more natives in our own gardens.

*Source: Dirzo et al. 2014. “Defaunation in the Anthropocene.” Science 345(6195); 401—06, as cited in Nature’s Best Hope, Douglas W. Tallamy [Timber Press, 2020].

 DEER-RESISTANT NATIVE PERENNIALS 
 

While we can’t call anything “deer proof” anymore, here are some of my favorite deer-resistant native perennials that will bring you color and interest throughout the year. For more information, get Deer-Resistant Native Plants for the Northeast by Ruth Rogers Clausen and Gregory D. Tepper (Timber Press, 2021). I’ve found it very helpful this year, with the deer population soaring here in New Jersey.

Reminder: Perennials are plants that come up every year, unlike annuals that you replant every spring. Some perennials, like blue flag iris, are long-lived. Some, like columbine, have a shorter life span but tend to reseed around your garden.

Anise hyssop (Agastache foeniculum). This easygoing perennial shows off its blue to purplish flowers in summer and is a pollinator magnet. Its leaves have a fresh anise scent.

Red columbine (Aquilegia canadensis). This is important because it is an early bloomer and is very attractive to its most important pollinator, the ruby-throated hummingbird. It self-seeds, so you will find it growing in unexpected places; perfect for a naturalized garden.

False indigo (Baptisia australis). This cool perennial sends up spikes of blue pea-like flowers in mid to late spring. When the flowers are done, they leave seedpods of pale blue-green, which turn blackish brown as they age. Great in dried arrangements. Blue false indigo is a host plant for wild indigo duskywing butterflies, making it not only showy but useful.

Spotted joe-pye weed (Eutrochium maculatum). This is the perennial that puts on a midsummer show along some highways, growing up to seven feet tall! Its sturdy stems are topped with pink/purple flower heads. Good as a cut flower, too.

Blue flag (Iris versicolor). If you have a wet area in your yard, this is for you. Elaborate blooms rise above long, narrow leaves in late spring, with yellow highlights drawing in their primary pollinator, bees. It is great planted in wet areas and in rain gardens, but also does well in regular garden conditions.

Blazing star (Liatris spicata). Spikes of violet flowers rise above the upright leafy stems, attracting butterflies, bees, and hummingbirds. Great cut flower, too. The seeds are important food for songbirds in fall. All this is why blazing star is such a star in the garden!

Scarlet bee balm (Monarda didyma) and wild bergamot (Monarda fistulosa). To attract hummingbirds to your garden, plant these hardy perennials. Scarlet bee balm’s brilliant red flowers are a hummingbird magnet, while wild bergamot offers more subtle pinkish-purple blossoms. Both flower like crazy, providing pollinator-attracting blooms for several weeks in summer. And not only can you toss the flowers into your salad, but you can also crush the leaves and rub the juice on skin to help repel mosquitos.

New York ironweed (Vernon noveboracensis). This crazy-tall perennial is a favorite of mine. Planted below my deck, the blooms rise above the floor, six feet high! Its late-summer blooms provide for butterflies far into fall. Add this sun-loving plant to your pollinator gardens and rain gardens for a stunning display.

Blue star (Amsonia hubrichtii) has nice spring flowers for pollinators, but I plant it for its stunning bright-gold fall color. The icy blue flowers appear in mid-spring. Blue stars are easy to grow and drought-tolerant once established. This considerable perennial is not a New Jersey native (local to Maryland and Virginia), but still deserves a space in your garden.